Northeast Weather Blog

Kyle to brush New England

By: sullivanweather, 8:06 AM GMT on September 28, 2008

Hurricane Kyle

Latest IR image of Hurricane Kyle.


Current watches, warnings and advisories.


Eastern US current watches/warnings

------

Regional Forecast


Synopsis – Issued 9/28 @ 4:00am


The Southeastern US cutoff/nor’easter that has brought rain, wind, and general dreariness the last several days has opened and is beginning to lift. Caught in the southerly flow along its eastern flanks is Hurricane Kyle, which is currently accelerating towards the north and should pass close enough to southeast Massachusetts and Downeast Maine to sideswipe those areas with windswept rain on tropical storm force winds Sunday and Sunday night. The region will dry out Monday as shortwave ridging builds, although the general trough over the Eastern US never completely lifts out and a new shortwave will amplify this trough by midweek. Unsettled weather will move back over the region with this feature and stick around until at least Friday.


Near-term – Issued 9/28 @4:00am


Warm conveyor precipitation is ongoing this overnight across eastern Massachusetts and much of the State of Maine. Many of these areas have already seen over an inch of rain with some localized areas seeing as much as 3 inches. A very juicy airmass remains over this region with precipitable water values in excess of 1.75”. Southerly flow transporting the moisture over this region will begin to back towards the southeast and east and increase in strength as Hurricane Kyle approaches but more on that later. Most of this rain will continue into the early morning hours of Sunday. Meanwhile, an inverted trough, with the remnants of the nor’easter which is banked up along the east side of the Appalachians along its western flank, lies just south of the Mason-Dixon line helping to generate a band of heavier rain across southern Pennsylvania. These showers are moving towards the north around 20-25mph and should be over the I-80 corridor by dawn. Additional showers extend from western New York into southern Ontario, pivoting around the upper trough axis as it gradually lifts.


Short-term – Issued 9/28 @4:00am


Aforementioned batches of precipitation will be ongoing during the morning hours. The inverted trough will continue to pull north, lifting rain into south-central New York to western New England. Along the shores of New England, from Cape Cod and Nantucket on north, is where it’ll start to get dicey. Hurricane Kyle will move about 50-75 miles east of Cape Cod during the early afternoon, but as it approaches winds aloft will increase and shift to an easterly to northeasterly direction. Deeper tropical moisture will be flung back across southeast Massachusetts and the increase in wind aloft and frontogenesis within the west side of Kyle’s circulation will lead to much more efficient precipitation generation and the chance for tropical storm force winds to come over the region, especially in gusts. Rainfall amounts of 2-3 inches over this area have already occurred over the previous 24-36 hours and these amounts could easily be doubled over the course of the day. Localized flooding may occur along streams and flashier rivers. The stronger wind gusts over increasingly saturated soils will also enhance the potential for fallen trees and power outages. Although most of Kyle’s fury is located in the eastern semi-circle, as Kyle moves north of the Gulf steam and encounters cooler waters it will begins to show signs of extra-tropical transition, one of these usually being a shift of convection to the western side of the storm. This possibility will have to be watched. Along the coast, tides, already astronomically high, will be running a couple feet above normal and should lead to minor to moderate coastal flooding and overwash. Large swells generated over the last several days from persistent long-fetch southeasterly flow and now Hurricane Kyle will lead to large breakers along the coast that will also cause moderate to severe beach erosion. Later in the afternoon Kyle will enter the Gulf of Maine and move up the Bay of Fundy during the evening. This puts Downeast Maine very close to the center of circulation and a better chance for seeing sustained winds to tropical storm force. Just like the Cape, 2-4 inches of rain, and 2-3’ above normal tides are likely. Back towards the west across the remainder of the Northeast, clouds and scattered showers will remain throughout much of the afternoon and evening with slight clearing taking place overnight. Highs today will run in the 70’s along the coastal plain, as maritime tropical airmass remains intact. Further inland highs will climb into the 60’s. Overnight lows will fall about 10-15 degrees from daily highs.


Mid-term – Issued 9/28 @4:00am



Monday will begin with brilliant sunshine, aside from localized areas of fog, and fairly mild temperatures. Partly to mostly sunny skies will be the rule for much of the day. 925mb temperatures will range from 10-12°C over Maine and 12-15°C from north to south elsewhere across the region. This will bring highs up into the 70’s across much of the southern half of the region with mid to upper 60’s across the north. Mainly clear skies will continue Monday evening, along with light winds as a weak area of surface high pressure will be centered over New York State. High clouds will increase over western sections after midnight as the next system approaches, but temperatures across much of the Northeast will drop some 20-25 degrees from their daily highs. 40’s across the northern interior with 50’s along the coastal plain looks good at this time for overnight lows Monday. The New York and Philadelphia UHI areas may even remain in the low 60’s. Clouds continue to increase Tuesday, lowering and thickening from west to east. Precipitation will move into the Niagara Frontier and the Upper Ohio Valley across western Pennsylvania during the afternoon hours in response to a digging shortwave trough over the Great Lakes. Divergence will increase ahead of the trough Tuesday afternoon and evening, aiding in the development of a band showers, which may contain embedded low-topped convection, given the marginal CAPE and somewhat favorable kinematics. A 140kt jet streak develops over the Northeast as the longwave trough over the region sharpens Tuesday night. Additional lift provided by sharp PVA will make this system an efficient rainfall producer given all the factors listed above. As rain moves into the remainder of New York and Pennsylvania it may become heavy at times and could easily bring an inch or more to many locales, especially across the Finger Lakes region. New England should see another dry day on Tuesday and should see a mostly sunny start. Clouds will increase during the day, mainly high clouds, but enough filtered sunshine should penetrate for a fair day, especially as one heads north towards Maine. Highs Tuesday will be kept some 3-5 degrees cooler than Monday’s readings but a few degrees warmer at night as diurnal variation decreases with the clouds and precipitation over the region. Where clouds are thinnest across northern New England temperatures will be quite similar to Monday’s readings.


Long-term – Issued 9/28 @4:00am


The aforementioned shortwave will continue to induce a sharpening of the trough over the region, as it eventually takes on a negative tilt and attempts to close off. Current indications are for a half in to an inch of precipitation, especially across the eastern half of the region as Atlantic moisture gets drawn into the system. In fact, a few global models, namely the GFS, shows phasing of this system with a potential hybrid low moving out of the Gulf over the western Atlantic that could bring enhanced storminess over the same areas that will have to deal with Kyle over the next 24-36 hours. While this scenario is possible, the most likely outcome will be for these two features to remain seperate entities. Seasonably cool air moves across the Northeast as the storm lifts out. 850mb temperatures fall to between 0 and 3°C and given somewhat moist, cyclonic flow over the region minimum temperatures will be near to slightly below normal with daily max’s 5-10 degrees below normal Wednesday through Friday. Mainly fair weather is the early call for next weekend, but a backdoor cold front may bring additional chill down from the north.
___________________________________________________________


Radar: Northeast Region Loop

NE radar


___________________________________________________________

Local SST's

Northeast SST's

Updated: 10:10 AM GMT on September 28, 2008

Permalink

1-2 Punch for Northeast

By: sullivanweather, 10:49 AM GMT on September 26, 2008

Current watches, warnings and advisories.


Eastern US current watches/warnings

------

Regional Forecast


Synopsis – Issued 9/26 @ 6:45am


Major rain event is underway over a large portion of the Northeast as circulation around vertically stacked low over the Southeast, the nor’easter, and deep-layer ridge south of Newfoundland, both anchored in their respective positions, funnels in deep tropical moisture on a southeast flow extending 1,500 miles into the western Atlantic. This plume of moisture will continue to pump into the Northeast through Saturday with the heaviest rain concentrated along the New York-New England border region, especially upslope areas of the Berkshires, Catskills, and southern Adirondacks where rainfall amounts may exceed five inches. The surprise lies at the end as newly formed Tropical Storm Kyle is bringing up the rear and should come close enough to coastal Massachusetts and Downeast Maine to directly affect these areas. The deep trough finally lifts out of the Northeast by Monday, replaced by shortwave ridging that will begin to dry the region out. However, just as quickly as the ridge moved in, it’s gone by late Tuesday. The next trough, reminiscent of a wintertime clipper low, quickly digs into the Great Lakes region, spreading precipitation back over western sections Tuesday afternoon and across the remainder of the Northeast by Wednesday. This energetic low spawns a deep vertically stacked low over Quebec that should drive a sharp cold front through the region, perhaps delivering the coldest airmass of the young autumn season.

Short-term – Issued 9/26 @6:45am


A shield of steady moderate to occasionally heavy rain extends from northeast Pennsylvania across all of southeastern New York State to coastal Massachusetts this morning. Rainfall rates within this band of rain have been averaging a tenth to a quarter inch an hour and should become heavier as deeper tropical moisture continues to advect into the Northeast. Outside of this area of rainfall widely scattered showers cover much of southern Pennsylvania to southern New Jersey, where the western flank of the steady precipitation is found. Temperatures across the region this morning are being held in check by cloud cover as most locations across the interior are in the 50’s with low 60’s along the southern coastal plain. Flood watches have been raised across much of eastern New York and southern New England, despite recent dry times, as expected rainfall of 3 inches or more in a widespread fashion may push smaller rivers and tributaries out of their banks, though main-stem rivers ought to handle what falls.

The rain will continue to advance northwestwards today as the inverted trough continues to press northwards along the coast and a 30-40kt southeasterly low-level jet advects deeper moisture across the region. Precipitable water values rise from .75” to 1.5” from northwest to southeast this morning to 1.5”-2.25” from northwest to southeast by this evening. Strong frontogenesis on the northwestern edge of the precipitation shield and training rainbands moving in off the ocean will lead to flash flooding concerns given the juicy airmass in place. In addition to the rain, a raw easterly wind will blow from 15-25mph at times across a good portion of the area east of the Appalachians, especially along the coast where gusts may approach 40mph. Waves of rain will continue to rotate in off the ocean around the broad circulation of the vertically stacked low to the southwest of the region through Saturday. Temperatures will show very little diurnal variation during the next 36-48 hours and should warm several degrees overall as a higher dewpoint airmass moves in. Temperatures along the coastal plain will generally remain in the 60’s with interior locations remaining in the 50’s. Exceptions will be on the northwestern periphery of the region where enough filtered sunshine may push temperatures into the 60’s, especially west of the Appalachians. Tonight and Saturday temperatures under the precipitation shield should rise several degrees as the maritime tropical airmass arrives. Coastal New Jersey may climb into the low 70’s on Saturday if some breaks of sun manage to appear.

Mid-term – Issued 9/26 @6:45am

Attention shifts to Tropical Storm Kyle Saturday night, which may be a hurricane by that time. Kyle is currently located at the southern end of the aforementioned deep moisture plume, several hundred miles south-southwest of Bermuda. Kyle is caught in the deep southeasterly flow between the Southeast cut-off low and the deep-layer ridge south of Newfoundland, which should steer the cyclone precariously close to Cape Cod. Residents there should prepare for at least tropical storm conditions that may bring power outages to the area. Last year extra-tropical Noel passed by within 50 miles of Cape Cod causing widespread damage, though it was a much larger, stronger storm it does serve as comparison since it’s recent. Models are also hinting at a secondary area of heavy rainfall in juxtaposition with Kyle moving up the coast across New Jersey and New York.

The track of Kyle, and how close it gets to New England, will largely be determined by the cut-off low over the Southeast. Kyle will be backing towards the north-northwest, or even northwesterly, over the next 24-36 hours as it rounds the northeastern periphery of the Southeast cut-off and the southwestern periphery of the western Atlantic ridge. However, the Southeast low is forecast to begin filling and lift out Saturday night, which should put Kyle back on a northerly heading. Where this turn occurs will be crucial for Cape Cod, Nantucket and Martha’s Vineyard. Although these areas will be on the western/weaker side of the storm there’s a good chance of these locations seeing tropical storm force winds and heavy rain for a 6 hour period or more between midnight Saturday night and Sunday morning. Kyle will begin to feel the westerlies by Sunday and begin to recurve. This may spare Maine a direct hit, but Nova Scotia should take it on the chin from Kyle. It remains to be seen whether or not Kyle will ever attain hurricane status or maintain that status up until landfall. Regardless, heavy rain and storm force winds should affect areas from Freeport, Maine on east into the Canadian Maritimes. Further west, the weakened version of the nor’easter will move to the east side of the Appalachians bringing murky weather to much of the remainder of the region; scattered showers, low clouds, fog and cool temperatures. It will slowly clear out Sunday night and Monday as shortwave ridging builds into the Northeast via the Ohio Valley.

Long-term – Issued 9/26 @ 6:45am

The next shortwave, a rather potent one, will dig down the western side of the longwave trough over eastern Canada. This shortwave will spawn a clipper-like low that will race across the region Tuesday afternoon into Wednesday. Showers are likely to accompany this system and there may be a rumble or two of thunder as the system looks very energetic. As the low moves towards the Labrador Coast it should rapidly intensify and become vertically stacked, carving out a deep trough over southeastern Canada. The end result will be for cooler than normal temperatures and slightly unsettled weather to close out next week with the cold pocket of air overhead. Very autumn-like to begin October.


___________________________________________________________


Radar: Northeast Region Loop

NE radar


___________________________________________________________

Local SST's

Northeast SST's


Current SST's off the Northeast Coast.

Permalink

Nor'easter to bring wind/rain/coastal flooding

By: sullivanweather, 3:42 PM GMT on September 24, 2008

Current watches, warnings and advisories.


Eastern US current watches/warnings

------

Regional Forecast

Synopsis - Issued 9/24 @4:40am


Deep-layer ridging will remain in place for one more day over the Northeast, bringing another stellar day to the region on Wednesday. This ridge will slowly move offshore and build over the western Atlantic over the next several days as a complex low pressure system organizes in the waters off the Southeast Coast along a stalled out frontal boundary. A nor’easter, for all intents, will be the end result of the complex interaction between a deep mid/upper cut-off over the Southeast, the surface low along the coast, which may develop tropically or sub-tropically, and the strong high centered south of Newfoundland. In addition, a tropical disturbance (93L) that has been lingering for days around Puerto Rico and Hispaniola should become incorporated into the mix. Whether or not this system fully develops into a tropical cyclone, the deep moisture connection with the tropics will ensure heavy rainfall amounts across a wide region of the Northeast by the weekend. The jet stream over North America becomes highly meridional next week as the season’s first nor’easter lifts into Canada. A strong ridge will develop over the Inter-mountain region out west as a sharp shortwave re-amplifies the trough over the Great Lakes/Northeast. A possible second nor’easter and perhaps the coldest airmass of the season could follow by the middle to latter part of next week to begin October.


Short-term - Issued 9/24 @4:40am


The Northeast will bathe in sunshine once again as high pressure dominates the region. There will be an increase in high clouds late in the day across the coastal regions but that should do little to impede temperatures from rising several degrees above normal. High’s across the higher terrain of north-central Pennsylvania to the Catskills, then on northward to northern New York and much of central/northern New England will see highs in the mid to upper 60’s. Elsewhere across the region highs should easily climb into the low to mid 70’s with the lake plains south of Lake Ontario and Erie reaching the upper 70’s. Ridging holds on tonight allowing for mostly clear skies and light winds for most, ideal radiational cooling conditions. Lows will once again drop into the 30’s across the northern interior with 40’s across much of the remainder of the interior. However, along the coastal plain, clouds will be increasing as will an onshore flow. This ought to keep temperatures held up into the upper 50’s to low 60’s, perhaps rising as the night progresses.

Clouds continue to increase from the south on Thursday as high pressure loses its grip on the region. A much-advertised low pressure developing off the Southeast Coast will slowly back westwards, towards South Carolina. Ahead of this system, an inverted trough will move north, towards the region, in tandem with a mid-level vorticity lobe circulating around a large mid/upper level cut-off settling into position over the Southeast. As this wave of low pressure approaches, the pressure gradient between itself and the high over the Canadian Maritimes will tighten over the region and the winds will pick up. Along the coast, northeast winds will increase to above 20mph with gusts to 35mph while inland areas see a lighter 10-15mph breeze, at times. Still just a prelude of what’s to come, much of the region should eek out one last pleasurable day. The northern/western interior will still be far enough away from the low pressure to remain mostly clear and highs once again will run several degrees above normal, into the upper 60’s to mid 70’s. Further south and closer to the coast one goes, the thicker the clouds become and the higher one’s rain chances before day’s end gets. Highs here should climb into the upper 60’s to mid 70’s as well but could quickly fall back into the mid 60’s once precipitation begins. The approaching trough should be close enough to spread rain into southern New Jersey early to mid afternoon and up to the New York/Philadelphia metro areas by dusk. Residual dry air in the lower levels may take awhile to erode and precipitation may evaporate before hitting the ground along the leading edge, especially across the interior but the onshore flow will quickly moisture the atmosphere heading into Thursday night. Rain, heavy at times, will fall along the coast within the vicinity of the inverted trough as it moves north with lighter rainfall across the interior developing across the eastern 2/3rds of Pennsylvania, to south-central New York and southern New England. Lows will fall back into the 50’s under the clouds and precipitation with 40’s to the north where clouds will be increasing but still thin enough to lose some of the day’s heat.


Mid-term - Issued 9/24 @4:40am


Rain will continue to overspread the Northeast from south to north during the day on Friday as the inverted trough slowly works its way up the coast. Easterly to southeasterly low-level jet of 30-35kts will help to transport copious amounts of Atlantic moisture into the Northeast as precipitable water values rise to ~150% of normal. Strong convergence along the inverted trough and developing coastal front combined with a lobe of mid-level energy atop the inverted trough will make for efficient rainfall production right along the coastal plain from central New Jersey to southern New England with lighter, more stratiform precipitation to the northwest across the interior. Widespread 1-2” amounts along the coast with amounts of a quarter to a half-inch across the southern interior will be common from this first round of rainfall. Heaviest rain moves to the Maine Coast Friday night as onshore flow across the remainder of the region keeps low clouds, fog and scattered showers around. Additional pockets of mid-level energy will ride north along the coast during the first half of the weekend, enhancing rainfall as they pass through as the low pressure system over the Southeast slowly consolidates and heads northeastwards. This low will pass by off the coast, but close enough to continue the precipitation across the eastern half of the region on Sunday as the western sections slowly clear out. There’s still a few questions concerning the eventual evolution of this storm. The weakness in the atmosphere this developing nor’easter will create in the western Atlantic should draw in the tropical disturbance, 93L, in whatever state it happens to be, into the overall circulation of the storm. This increase in tropical moisture across the Northeast could lead to flash flooding should the storm move close enough and draw in enough moisture over areas hit by Friday and Saturday’s rainfall. The long easterly/southeasterly fetch should also build seas, leading to beach erosion and minor to moderate coastal flooding during high tide cycles beginning on Friday and especially by the weekend. Winds will also increase as the more buoyant tropical airmass advects into the region eroding the inversion. Winds will be strongest along the coast and the higher terrain above 1500’ across the interior; around 25-30mph. Elsewhere winds will generally be under 20mph but may reach there in gusts.


Long term - Issued 9/24 @4:40am


General mid/upper level troughiness will linger over the Northeast on Monday but a weak surface ridge axis should keep the region dry, despite varying levels of mid/high clouds. Temperatures will be near seasonable levels for the end of September. Complications arise during the remainder of the long term as current indications show ~3 standard deviation anomalies in the major teleconnection patterns that highly influence the weather here in the Northeast (PNA/NAO). The highly positive PNA/negative NAO pattern point to an anomalously deep eastern US trough developing during the middle of next week. What’s unclear at this point is where the trough axis will set up and how deep this trough will be as models have been wrestling between varying scenarios the last couple days. Aside from the obvious differences in evolution between runs, one thing in common between all the runs is a rather strong southward push of polar air and the development of a significant low pressure system over the eastern US/western Atlantic. A few runs have been cold enough to deliver the first flakes of the season across the higher terrain of the Adirondacks to the Presidential Range and bring an end to the growing season for much of the interior. It’s quite possible the beginning of October will feel like the end of October.



___________________________________________________________


Radar: Northeast Region Loop

NE radar


___________________________________________________________

Local SST's

Northeast SST's


Current SST's off the Northeast Coast.






Updated: 3:53 PM GMT on September 24, 2008

Permalink

Frosty start; continued dry

By: sullivanweather, 8:39 AM GMT on September 19, 2008

Current watches, warnings and advisories.


Eastern US current watches/warnings

------

Regional Forecast

Synopsis - Issued 9/19 @4:40am


Surface high pressure crests over the Northeast this morning bringing a widespread frost to the interior with a killing freeze expected across much of the North Country under clear skies and light winds. Heights build aloft and weak warm air advection ensues this afternoon into the first half of the weekend allowing for a moderation of temperatures under continued mostly clear skies. Another cold front will drop down from the north on Sunday and move off the coast by evening but once again moisture is lacking so any precipitation should be widely scattered and confined to the higher terrain of the Northeast Kingdom. Strong high pressure quickly builds over the Northeast behind this front bringing more fair but below seasonable temperatures to the region.


Short-term - Issued 9/19 @4:40am


It’ll be a frosty start to the day across the northern interior from Bradford, Pennsylvania to Montpelier, Vermont. Temperatures are currently in the mid to upper 20’s across a wide region from the Adirondacks to the banks of the Allagash River. Outside of this area temperatures are mainly in the low to mid 30’s across much of the northerntier of Pennsylvania, upstate New York and interior New England. Temperatures are much warmer along the coastal plain and urban areas with Central Park in New York City reporting 56°F at the 4am ob. To go along with the cold temperatures, areas of dense fog have developed in the river valleys and other waterways/low lying areas. Brilliant sunshine will greet the day and temperatures will quickly rise in response. However, the rise in temperatures will be truncated by a shallow mixing layer due to strong high over the region, likely keeping highs stuck in the 50’s across the higher terrain, with 60’s common across the remainder of the interior. Perhaps the New York and Philadelphia urban areas could reach 70°F, along with coastal locales of southern Jersey and lower elevation areas along the Mason-Dixon line. High pressure will move offshore tonight but winds will remain light and skies clear. Temperatures will plummet once again after dusk, with frosty conditions likely across the North Country a second morning in a row. Overall temperatures should range from 4-8°F warmer than the night previous so frost will be unlikely in areas borderline for frost this morning, but still a rather chilly mid-September night. Lows will fall into the upper 20’s to low 30’s across northern New York and New England. Upper 30’s to mid 40’s will be found elsewhere across the interior with 50’s along the coastal plain.


Mid-term - Issued 9/19 @4:40am



The center of high pressure will be well offshore by Saturday but a low-level ridge axis will extend back over the region, providing another excellent day. High clouds will increase late in the day across the north as a cold front approaches but otherwise, sunny skies will be the rule. 850mb temperatures will range from 9-11°C from north to south, with mixing to just above the 900mb level. Surface highs will range from the upper 60’s north to the mid to upper 70’s south. The cold front pushes across the border overnight Saturday, with clouds increasing and some light showers dropping across northern New York and New England. To the south skies will be mostly clear during the evening but clouds will increase after midnight. These clouds will keep temperatures held in the upper 40’s to low 50’s north, mid to upper 50’s south. The cold front continues through the region on Sunday with nothing more than some clouds and a few sprinkles. Winds will shift to the north and temperatures will struggle to climb out of the 50’s across the north. Further south, across central/southern Pennsylvania and New Jersey where the front comes through later in the morning temperatures will rise into the 70’s with 60’s common between these two areas. The front will be offshore by Sunday evening with cold advection in full swing. The 0°C isotherm @850mb drops into northern New England as skies clear and winds slacken. Where the atmosphere decouples and winds calm across the north, areas of frost will develop. Elsewhere it will be a typical early autumn night, with the slight nip in the air as temperatures fall into the 40’s and 50’s.


Long-term - Issued 9/19 @4:40am



A sprawling dome of high pressure builds behind this front early next week continuing the pattern of sunny mild/warm afternoons with clear cool, in some cases frosty, nights. Sunday’s cold frontal boundary will stall off the East Coast as the pattern over the western Atlantic becomes blocky next week. Models are hinting at the development of low pressure at the tail end of this frontal boundary by midweek, possibly tropical or sub-tropical in nature. If this system does develop there’s an outside chance that it could directly impact the region but the most likely scenario is that it heads very slowly out to sea with only fringe effects skirting by coastal areas. The center of the surface high will have moved to the Canadian Maritimes by midweek but will wedge down the east side of the Appalachians. These two features will change in position very little to close out the week resulting in a persistent onshore flow and an increase in clouds and moisture. In addition, high surf and minor coastal flooding/beach erosion may become an issue with time as long easterly fetch builds water levels along the coast and astronomical high tides approach. Temperatures will rise to seasonable levels for late September region-wide, although the diurnal change along the coast under the clouds and/or precipitation will be less than areas across the far interior.


___________________________________________________________


Radar: Northeast Region Loop

NE radar


___________________________________________________________

Local SST's

Northeast SST's


Current SST's off the Northeast Coast.



Permalink

Fair and dry this week

By: sullivanweather, 4:17 PM GMT on September 16, 2008



Current watches, warnings and advisories.


Eastern US current watches/warnings

------

Regional Forecast

Synopsis - Issued 9/16 @12:30pm

A sprawling area of surface high pressure extends from the Southern Plains to Nova Scotia and will remain so through tomorrow. For the Northeast this means plenty of clear skies and seasonable temperatures both Tuesday and Wednesday. A cold front with polar origins will approach Wednesday night from Canada but will not have much moisture to work with. A few showers or sprinkles will skirt by northern New York and New England but most everywhere else across the region will just see an increase in clouds and a wind shift. Leftover cold air advection makes for a breezy, but otherwise fair Thursday that will have a distinct autumn feel. Deep-layer ridging builds back over the Northeast Thursday into the first half of the weekend, delivering more fine early autumn weather, although the initially chilly airmass over the North Country Thursday night will make for a killing freeze/frost more widespread than last Wednesday night. A weak cold front will approach during the second half of the weekend but once again lacks moisture and really lacks cold air, too. Heading into the beginning of next week the fair weather continues as temperatures climb back above normal and humidity increases some. The next chance for any widespread rainfall of significance doesn’t come around until the middle of next week.


Detals coming later. Right now it's off to work.

___________________________________________________________


Radar: Northeast Region Loop

NE radar


___________________________________________________________

Local SST's

Northeast SST's


Current SST's off the Northeast Coast.


Permalink

Ike bears down on Texas

By: sullivanweather, 5:24 AM GMT on September 12, 2008

Tropical Update


Hurricane Ike


Auto-updating IR color enhanced satellite image of Hurricane Ike.


As of the 9/11 10pm CDT National Hurricane Center advisory, Hurricane Ike was located at 26.3°N 90.4°W, or about 340 miles southeast of Galveston, Texas. Ike was moving towards the west-northwest around 12mph. Maximum sustained winds are near 100mph with a reconnaissance measured minimum pressure of 956mb.


Ike is a large and extremely dangerous hurricane, displaying a radius of tropical storm force winds that rivals some of the biggest Atlantic tropical cyclones of all-time. Moderate to strong convection associated with Ike covers the entire central Gulf of Mexico. Ike’s very large size and gradual pressure drop from the periphery of the storm to the eye has allowed for maximum sustained winds to remain in check at 100mph. However, the strongest winds with Ike are concentrated in two concentric rings around the circulation center. One wind maxima is associated with the inner core of the storm and the other rounding the circulation about 80 miles away from the center of circulation. In addition, the large circulation of Ike has drawn in dry air far away from the center over the western Gulf of Mexico during the previous 24 hours causing an asymmetric convective pattern and pockets of little to no convection within the storm’s radius. Other than growing even more during the previous day, Ike’s current state is status quo. Outflow is excellent in all quadrants, though earlier in the day outflow was being restricted in the western quadrant, but now outflow is expanding west rapidly. A well-defined equatorward outflow channel extends for several thousand miles in a curved arc accelerating away from the east side of Ike then south into the central Caribbean, across Central America and into the East Pacific curling west. From a satellite perspective, Ike is a sight to behold.

The intensity forecast for Ike is problematic. Should Ike lose one of its wind maximas, outer or inner, the storm is likely to intensify as one dominant ‘eyewall’ comes to prominence. However, this has yes to occur thus far and Ike’s awkward structure has remained relatively stable. At least for the next 12 hours no major changes in strength should occur being that Ike has been a slowly evolving system. Beyond 12 hours there’s a small window for strengthening before the center comes ashore. The large-scale environment has gradually become more favorable for intensification than it had been previous. Dry air that had been over the western Gulf has been mixed out, for the most part, and light westerly shear is all but gone as an upper level anti-cyclone rest atop Ike. Perhaps the only unfavorable condition for intensification is a warm upper-troposphere, which is limiting the thermodynamic environment above the 300mb level. It is unlikely that Ike will weaken before making landfall and should remain at least a category two storm or could even strengthen to a borderline category three. It should once again be noted that the large expanse of hurricane and tropical storm force winds would affect large swaths of coastline. The maximum sustained wind speeds with Ike could be felt over a wide area along the coast, up to 100 miles. Ike’s large size, while currently inhibiting development, will also ensure a slow spin-down of the storm once it’s over land. It is entirely possible for Ike to remain a hurricane as many as 24 hours after landfall as it crosses eastern Texas. Eventually, Ike will weaken to a tropical storm near the Arklatex region and to a depression soon thereafter over the Mid-Mississippi Valley.

The track of Ike is a bit more certain as the steering currents are well defined. A shortwave trough moving into the Central Plains over the next 24 hours will erode the 500mb ridge axis to the north of Ike and shift the mid-level ridge center to the northeast of the cyclone eastward. This will allow for Ike to begin turning towards the northwest the north-northwest very close to the Texas coastline near midnight Friday night. However, as discussed above, where the center comes ashore is a moot point. The radius of maximum winds will ensure that a large section of the coast sees the brunt of the storm. The center of Ike will then move through eastern Texas on Saturday where it will meet up with the remnants of Lowell during Saturday evening and be captured by the westerlies and accelerated through the Mid-Mississippi Valley on Sunday to the eastern Great Lakes region by Monday.

Ike impacts will be felt far and wide. From wind, to rain and surge, Ike should bring extremes of all three major tropical cyclone threats. The large wind field of Ike over the Gulf of Mexico has piled water up in the western Gulf up to 4’ above normal tides well out in advance of the storm itself. As the stronger winds of Ike come over the shallow waters of the western Gulf, the surge should rise even faster. Being that Ike has a good chance to come in at a right angle to the coast only compounds the issue. The many bays and estuaries along the coast are likely to see the highest surges with Ike, which should approach up to 20 feet. Where the center comes ashore and up to 150 miles up the coast, a 10-15 foot storm surge should push ashore. Outside of the highest surge region by 50-75 miles to the north and south the surge should range from 8-10’ above normal tides. A moderate surge will also affect the Gulf coast from Tampico, Mexico to Panama City Florida of up to 5-6 feet. Should Ike gain strength to a category three, these surges could possibly be higher. Where the highest surge comes ashore, up to several miles inland could get inundated, barrier islands may have new channels cut through them and the coastline is likely to be permanently altered. The storm surge, if not prepared for, could be the most deadly facet of Ike. There will also be very large battering waves on top of that surge capable of destroying well-built structures. Ike’s landfall location close just south of the Houston metro area should pile up a tremendous amount of water into Galveston and Trinity Bays as well. There’s much infrastructure along the shores of these bays that may be swept clean. The surge potential of Ike cannot be stressed enough.

Although winds with Ike won’t be of the extreme category, the area in which hurricane force winds will affect could extend close to 200 miles along the coast, with winds of category 2 strength possibly extending up to 100 miles along the coast. The large maximum wind radii will also keep the strongest winds over the same areas for extended periods of time. A 90-100mph sustained wind over a 3-4 hour period can cause considerable wind damage, comparable to an hour’s worth of category 3 winds. Usually, the wind begins the damage but the debris multiplies it. The extended period of near 100mph sustained winds should allow for the build-up of debris, increasing the wind damage potential. Ike, being a large hurricane with a rather low central pressure in relationship to the maximum sustained winds, won’t be in any rush to weaken after moving ashore and is likely to carry hurricane force winds far inland, perhaps as much as 100-150 miles with tropical storm force winds much further than that. These winds over inland areas will take down trees as soil saturates and power lines with them as they fall. Most of eastern Texas, western Louisiana, western Arkansas and southeastern Oklahoma should see tropical storm force winds from Ike at some point during the storm and is at risk for power outages. This risk increases towards inland areas of southeast Texas where the center moves through.

Rainfall from Ike will be a growing concern after the storm makes landfall. Ike has acquired a large moisture envelope to go along with its girth in windfield and will deposit this moisture over Texas, the Southern Plains, Mid-Mississippi Valley, northern Ohio Valley, lower Great Lakes, Southern Canada, New York and New England in time. Rainfall from Ike should effectively end the drought/dry conditions over the remainder of eastern Texas as amounts of rain from 5-10” will fall over a wide area with localized amounts up to 20” along the path of the center. These amounts will continue northwards but narrow in aerial expanse north of the Arklatex. As Ike interacts with the remnants of Lowell along a frontal boundary extending across the Mid-Mississippi Valley to the St.Lawrence Valley the rain shield will expand northeastwards. Across Missouri to northern Indiana 2-5” of rain should fall with localized amounts of up to 8”. Amounts will continue to taper across the Great Lakes region into southern Canada and the Northeast to 1-2” with localized 3” amounts.

As with any landfalling tropical cyclone, a tornado threat exists. The right front quadrant of the storm is where this threat is most prevalent and with Ike this area extends from Houston, Texas to Tyler, Texas and all points east to the Mississippi River.The tornado threat diminishes but still remains into Sunday across the lower and mid Mississippi Valley.

___________________________________________________________



Current watches, warnings and advisories.


Eastern US current watches/warnings

------

No updates to the Northeast forecast now. I wanted t concentrateon Ike


Regional Forecast

Synopsis - Issued 9/9 @2:30am

A vigorous mid-level disturbance associated with a sharp shortwave trough will move across southern Ontario and Quebec on Tuesday. At the surface, low pressure will move right up the St.Lawrence River Valley dragging a strong cold/occluded front through the Northeast. Showers and thunderstorms will accompany the passage of this frontal boundary, some of which may be severe. High pressure slowly moves through the Northeast Wednesday and Thursday, bringing fair weather and possibly setting the stage for the first widespread frost of the season across the North Country Wednesday night. Meanwhile, a zonal split jet stream pattern briefly develops across North America, north of 40°N, sending a disturbance towards the region on Friday and also resulting in a narrow but strong ridge axis across the northern Gulf Coast that should steer Hurricane Ike to a landfall close to the Texas-Mexico border region by the start of the weekend. Whether or not Ike becomes incorporated into the mid-latitudes or rains itself out along the Rio Grande Valley remains to be seen. The upcoming pattern for next week largely assumes Ike will continue its incessant westward movement until encountering the Sierra Madres as deep-layer ridging over the Southern Plains suppresses Ike to the south. Spilt jet pattern quickly breaks down by Sunday as the jets phase and a strong extra-tropical cyclone develops near the Great Lakes region and moves across eastern Canada to the Labrador Coast sending a strong cold front through the region during the second half of this weekend. The resulting deep trough that carves out over eastern North America should send several strong autumn cold fronts over the course of next week with temperatures averaging below normal.


Short-term - Issued 9/9 @2:30am


Most ingredients will be in place for a widespread severe weather event on Tuesday. A vigorous mid-level disturbance will ride along the international border bringing strong PVA over the region. Jet dynamics are impressive, as the region will lie in the right rear entrance region of a 110kt jet streak over southern Canada. Strong forcing along a very sharp cold front will provide plenty of convergence in the low-levels. In addition, kinematics is about as strong as it gets this time of year in the Northeast; a 75-90kt jet @500mb, a 45-60kt jet @700mb and a 35-50kt jet @850mb. What will be lacking is strong thermodymanics, otherwise we may be talking about one of the biggest September outbreaks on record. Plenty of cloud cover (already evident on satellite and looking out the window) should limit the amount of insolation and keep mlCAPE under 1,000J/kg for the most part but some areas of deeper moisture pooling may create a more buoyant atmosphere, pushing those muCAPE values up to 1,500J/kg. Frontal timing isn’t ideal either, but as with most autumnal severe weather outbreaks of the past, all that really matters are those winds aloft. As the cold front punches into the Northeast a band of showers and thundershowers will already accompany it but these thunderstorms should become stronger as the day progresses. Bulk shear of 30-40kts should organize storms into bowing line segments and a squall line may develop at some point. The strong 40kt+ low-level jet will also promote the development of rotating supercells and veering winds above 850mb could help drop down a tornado or two. Large hail should be of too much concern given the high wet-bulb zero heights, but any of the stronger supercells should contain strong enough updrafts to easily punch deep into the sub-freezing layer to accrete large enough stones to survive the trip through the deep warm layer. Temperatures will range from the upper 60’s to low 70’s across western sections where precipitation moves into the region early. Further south and east where filtered sunshine may penetrate through the cloud layer temperatures should climb into the 70’s across the interior with highs into the low 80’s across the coastal plain. As the cold front blows through the region temperatures behind it should drop rather quickly, by some 10-15 degrees or more. Skies will quickly clear behind the front as well. The front pushes offshore during the evening hours, allowing for much of the region to clear out. The airmass behind the front is quite chilly and there’ll definitely be an autumn feel to the air. Lows will fall into the 40’s across the interior with 50’s along the coast. A northwesterly breeze will blow at 10-15mph and should be gusty during the evening during the strongest cold air advection.


Mid-term - Issued 9/9 @2:30am


Surface high pressure builds into the Northeast on Wednesday, bringing mostly sunny skies to the coastal plain with more coverage of cumulus inland. The airmass behind the front will be noticeably cooler and drier. 850mb temperatures will drop 10-12°C from Tuesday’s readings, ranging from near 0°C across the international border region, to 7-8°C down to the Mason-Dixon line. At the surface, this translates to highs in the 60’s across the interior with low to mid 70’s along the coastal plain. Some of the higher terrain of northern New York and New England may not make it out of the 50’s. Fairly blustery conditions will persist over New England, as continued cold advection should easily mix down the 15-20kt flow in the boundary layer. These winds slacken towards evening as high pressure crests over the region, centered near the Albany area. The combination of clear skies and light winds will allow for ideal radiational cooling conditions. Add in the longer nights and cool airmass overhead, areas of frost should develop across the North Country with patchy frost in sheltered valleys further south. Locally dense fog will also develop in river valleys and other low-lying areas, despite the dry airmass. A little less wind and a few degrees warmer on Thursday, but the fair skies will continue. Left exit region of a 100kt jetstreak brings an increase in high clouds Thursday night but should do little to prevent another night of decent radiational cooling. Some patchy frost may develop once again in the normally colder locales across the north but temperatures will be, on average, 5 degrees or more warmer than temperatures on Wednesday night. A disturbance riding the southern branch of the aforementioned rather zonal split flow jet stream pattern across North America will approach from the Ohio Valley on Friday and Friday night, spreading showers and thunderstorms across the southern half of the region while areas across northern New York and New England should remain dry. Temperatures will return to near normal.


Long-term - Issued 9/9 @2:30am


A strong upper disturbance is progged by global models to drop into central Canada on Saturday, amplifying and phasing the jet stream over North America. Low pressure will develop over the western Great Lakes and move into Canada as it rapidly deepens. Here in the Northeast, heights will build ahead of this developing powerhouse system. Friday’s system should move offshore and we may squeeze out a fine early autumn day. Temperatures should be near to slightly above normal, although there may be more clouds than sunshine. As low pressure wraps up over Canada it will swing a strong cold front towards the region on Sunday. Showers and thunderstorms are likely to accompany this frontal passage. Heading into next week a deep trough will set-up over eastern North America as the polar vortex drops to a position over Hudson Bay. Reminiscent of a winter-like pattern, several shortwave troughs and attending cold frontal passages will make for periods of showers separated by 24-36 hour intervals. Several model runs have shown the 0°C isotherm at 850mb penetrating deep into the Northeast at least once during next week. It should begin to feel very autumn-like as temperatures average closer to late September or early October-like readings.



___________________________________________________________


Radar: Northeast Region Loop

NE radar


___________________________________________________________

Local SST's

Northeast SST's


Current SST's off the Northeast Coast.


Updated: 5:39 AM GMT on September 12, 2008

Permalink

First frost; Ike aims Texas

By: sullivanweather, 6:39 AM GMT on September 09, 2008

___________________________________________________________



Current watches, warnings and advisories.


Eastern US current watches/warnings

------


Regional Forecast

Synopsis - Issued 9/9 @2:30am

A vigorous mid-level disturbance associated with a sharp shortwave trough will move across southern Ontario and Quebec on Tuesday. At the surface, low pressure will move right up the St.Lawrence River Valley dragging a strong cold/occluded front through the Northeast. Showers and thunderstorms will accompany the passage of this frontal boundary, some of which may be severe. High pressure slowly moves through the Northeast Wednesday and Thursday, bringing fair weather and possibly setting the stage for the first widespread frost of the season across the North Country Wednesday night. Meanwhile, a zonal split jet stream pattern briefly develops across North America, north of 40°N, sending a disturbance towards the region on Friday and also resulting in a narrow but strong ridge axis across the northern Gulf Coast that should steer Hurricane Ike to a landfall close to the Texas-Mexico border region by the start of the weekend. Whether or not Ike becomes incorporated into the mid-latitudes or rains itself out along the Rio Grande Valley remains to be seen. The upcoming pattern for next week largely assumes Ike will continue its incessant westward movement until encountering the Sierra Madres as deep-layer ridging over the Southern Plains suppresses Ike to the south. Spilt jet pattern quickly breaks down by Sunday as the jets phase and a strong extra-tropical cyclone develops near the Great Lakes region and moves across eastern Canada to the Labrador Coast sending a strong cold front through the region during the second half of this weekend. The resulting deep trough that carves out over eastern North America should send several strong autumn cold fronts over the course of next week with temperatures averaging below normal.


Short-term - Issued 9/9 @2:30am


Most ingredients will be in place for a widespread severe weather event on Tuesday. A vigorous mid-level disturbance will ride along the international border bringing strong PVA over the region. Jet dynamics are impressive, as the region will lie in the right rear entrance region of a 110kt jet streak over southern Canada. Strong forcing along a very sharp cold front will provide plenty of convergence in the low-levels. In addition, kinematics is about as strong as it gets this time of year in the Northeast; a 75-90kt jet @500mb, a 45-60kt jet @700mb and a 35-50kt jet @850mb. What will be lacking is strong thermodymanics, otherwise we may be talking about one of the biggest September outbreaks on record. Plenty of cloud cover (already evident on satellite and looking out the window) should limit the amount of insolation and keep mlCAPE under 1,000J/kg for the most part but some areas of deeper moisture pooling may create a more buoyant atmosphere, pushing those muCAPE values up to 1,500J/kg. Frontal timing isn’t ideal either, but as with most autumnal severe weather outbreaks of the past, all that really matters are those winds aloft. As the cold front punches into the Northeast a band of showers and thundershowers will already accompany it but these thunderstorms should become stronger as the day progresses. Bulk shear of 30-40kts should organize storms into bowing line segments and a squall line may develop at some point. The strong 40kt+ low-level jet will also promote the development of rotating supercells and veering winds above 850mb could help drop down a tornado or two. Large hail should be of too much concern given the high wet-bulb zero heights, but any of the stronger supercells should contain strong enough updrafts to easily punch deep into the sub-freezing layer to accrete large enough stones to survive the trip through the deep warm layer. Temperatures will range from the upper 60’s to low 70’s across western sections where precipitation moves into the region early. Further south and east where filtered sunshine may penetrate through the cloud layer temperatures should climb into the 70’s across the interior with highs into the low 80’s across the coastal plain. As the cold front blows through the region temperatures behind it should drop rather quickly, by some 10-15 degrees or more. Skies will quickly clear behind the front as well. The front pushes offshore during the evening hours, allowing for much of the region to clear out. The airmass behind the front is quite chilly and there’ll definitely be an autumn feel to the air. Lows will fall into the 40’s across the interior with 50’s along the coast. A northwesterly breeze will blow at 10-15mph and should be gusty during the evening during the strongest cold air advection.


Mid-term - Issued 9/9 @2:30am


Surface high pressure builds into the Northeast on Wednesday, bringing mostly sunny skies to the coastal plain with more coverage of cumulus inland. The airmass behind the front will be noticeably cooler and drier. 850mb temperatures will drop 10-12°C from Tuesday’s readings, ranging from near 0°C across the international border region, to 7-8°C down to the Mason-Dixon line. At the surface, this translates to highs in the 60’s across the interior with low to mid 70’s along the coastal plain. Some of the higher terrain of northern New York and New England may not make it out of the 50’s. Fairly blustery conditions will persist over New England, as continued cold advection should easily mix down the 15-20kt flow in the boundary layer. These winds slacken towards evening as high pressure crests over the region, centered near the Albany area. The combination of clear skies and light winds will allow for ideal radiational cooling conditions. Add in the longer nights and cool airmass overhead, areas of frost should develop across the North Country with patchy frost in sheltered valleys further south. Locally dense fog will also develop in river valleys and other low-lying areas, despite the dry airmass. A little less wind and a few degrees warmer on Thursday, but the fair skies will continue. Left exit region of a 100kt jetstreak brings an increase in high clouds Thursday night but should do little to prevent another night of decent radiational cooling. Some patchy frost may develop once again in the normally colder locales across the north but temperatures will be, on average, 5 degrees or more warmer than temperatures on Wednesday night. A disturbance riding the southern branch of the aforementioned rather zonal split flow jet stream pattern across North America will approach from the Ohio Valley on Friday and Friday night, spreading showers and thunderstorms across the southern half of the region while areas across northern New York and New England should remain dry. Temperatures will return to near normal.


Long-term - Issued 9/9 @2:30am


A strong upper disturbance is progged by global models to drop into central Canada on Saturday, amplifying and phasing the jet stream over North America. Low pressure will develop over the western Great Lakes and move into Canada as it rapidly deepens. Here in the Northeast, heights will build ahead of this developing powerhouse system. Friday’s system should move offshore and we may squeeze out a fine early autumn day. Temperatures should be near to slightly above normal, although there may be more clouds than sunshine. As low pressure wraps up over Canada it will swing a strong cold front towards the region on Sunday. Showers and thunderstorms are likely to accompany this frontal passage. Heading into next week a deep trough will set-up over eastern North America as the polar vortex drops to a position over Hudson Bay. Reminiscent of a winter-like pattern, several shortwave troughs and attending cold frontal passages will make for periods of showers separated by 24-36 hour intervals. Several model runs have shown the 0°C isotherm at 850mb penetrating deep into the Northeast at least once during next week. It should begin to feel very autumn-like as temperatures average closer to late September or early October-like readings.



___________________________________________________________


Radar: Northeast Region Loop

NE radar


___________________________________________________________

Local SST's

Northeast SST's


Current SST's off the Northeast Coast.


___________________________________________________________


Tropical Update


Hurricane Ike


Auto-updating IR color enhanced satellite image of Hurricane Ike.

As of the 11pm EDT National Hurricane Center advisory, Hurricane Ike was located at 23.2°N 84.3°W, or about 120 miles west of Havana, Cuba. Movement has been towards the west-northwest around 9mph. Maximum sustained winds are around 80mph, with higher gusts. Estimated minimum central pressure is 967mb.

Interaction with Cuba has done little to slow down Ike even though the storm has weakened from a category 4 to a category 1. The cyclone has managed to maintain hurricane status after 2 Cuba crossings, one from the Atlantic side and another from the Caribbean over the western tip of the country. The center of the storm moving into the Caribbean yesterday, instead of remaining over Cuba, helped Ike to retain some of it’s structure despite it’s rather ragged look. Ike also took a short trip over the western tip of the country today across rather flat land. Maximum sustained winds were down to only 75mph after all the interaction with land but central pressure had stayed under 970mb throughout

It has been very interesting to monitor the structural changes in Ike since its emergence as a tropical wave off the coast of Africa. What began as a broad center while Ike was a tropical storm for a few days suddenly tightened up as Ike finally developed an eyewall. Ike then went into a period of rapid intensification that saw intensity rise from a category 1 hurricane to a category 4 within 6 hours. At this point Ike was a very small hurricane, with tropical storm force winds that only extended 90 miles from the center. Ike then encountered and fought off northerly shear, causing the system to become asymmetric before finally eroding the inner core, weakening Ike to a category 2 storm. However, Ike remained resilient and once again strengthened to a category 4 storm upon coming under favorable conditions, displaying a 30 mile-wide eye. Now that Ike has interacted with Cuba, the wind field has expanded as tropical storm force winds now extend outwards 175 miles away from the center. Remarkably, the inner core of Ike emerged off the coast of Cuba this afternoon rather well intact. Ike now displays a tight central core of strong convection (the eyewall) around a small 10 mile diameter eye. In addition, two pronounced feeder bands are now beginning to wrap into the center of the storm. One extends well to the southwest of the Isle of Youth into the western Caribbean and curves cyclonically across western Cuba into the eastern semi-circle of the storm. The other band wraps around the northern and western quadrants across the southern Gulf of Mexico into the center on the western semi-circle of the storm.

The large-scale environment remains conducive for further strengthening. Ike has encountered some light westerly shear over the last 6-12 hours but upper level anti-cyclonic flow is centered just southeast of the center of Ike. Outflow is excellent across the northern and eastern quadrants, fair over the southern quadrant and restricted by the light shear over the western quadrant. This shear should weaken in the short-term as the weakness to the north of Ike moves away and ridging develops to the north of the cyclone. Dry air is of little concern and SST’s along the projected path of Ike range from 29-30°C. Considering the above, Ike should strengthen once again to a major hurricane over the next 24-36 hours and may do so rather quickly. The center of the storm will pass over water of very high oceanic heat content, the loop current itself and a loop current eddy that had broken off in July centered near 24°N 90°W. Once Ike becomes a major hurricane there appears to be little obstruction to the maintenance of this strength until landfall along the Texas coast.

Ike has been moving slowly on a wobbly course since emerging into the Gulf of Mexico, occasionally drifting north then west. Overall the motion has been west-northwesterly and this general motion should continue over the next 3 days. As Ike closes in on the Texas Coast a trough will be approaching from the northwest that should erode the deep-layer ridge over the northern Gulf Coast enough to bend the storm towards the north. Best early guesstimate at a landfall location lies between Corpus Christi and Galveston late Friday night or early Saturday morning.

As mentioned above Ike is a growing storm and should grow even further in the coming days. The National Hurricane Center projects tropical storm force winds to extend out over 200 miles away from the center as Ike approaches the Texas Coast. Being a large, powerful slow-moving storm, Ike will be able to generate a large storm surge and large battering waves. As with Katrina, large powerful Gulf of Mexico hurricanes moving into the shallows just offshore have been able to generate large widespread storm surges. With many bays and estuaries along the Texas Coast in the projected landfall area, there’s a high chance for a severe storm surge from Ike. Inland flooding will likely occur along the path of the center and where persistent feeder bands set-up. Widespread 4-8” amounts with local 12-18” along the path of the center and where feeder bands train will be common. As with most landfalling tropical cyclones, tornados in the right front quadrant of the storm (east of the center) and in feeder bands that follow the storm as it moves inland will be a concern for 2 or 3 days. Also, if Ike moves ashore as a strong category 3 or category 4 storm, sustained hurricane force winds will extend 50-75 miles inland along the path of the center. This can be a potentially devastating storm, especially if it takes a northern route towards the Houston metro area.

In the long term, Ike may hook up with moisture from the remnants of the East Pacific system, Lowell, over the central Plains and Mid-Mississippi Valley leading to more flooding across that region in what has already been a spring and summer of floods.

Updated: 4:47 AM GMT on September 10, 2008

Permalink

Hanna's East Coast impacts

By: sullivanweather, 2:03 PM GMT on September 05, 2008

Tropical Update



IR satellite image showing Hanna and Ike.


Tropical Storm Hanna


Auto-updating IR color enhanced satellite image of Tropical Storm Hanna.


As per the 9/5 8am EDT National Hurricane Center intermediate advisory, Tropical Storm Hanna was located at 28.2°N 78.8°W, or about 425 miles south of Wilmington, North Carolina. Hanna is moving towards the northwest at 18mph. Maximum sustained winds are 65mph with a 980mb estimated central pressure.


Hanna continues to battle her surroundings as persistent easterly to northeasterly shear continues to give the system an asymmetric appearance on satellite imagery. There’s also a good amount of dry air over the southwest quadrant of Hanna, extending from Cuba to the central Bahamas. The combination of these factors has not allowed for Hanna to become any better organized, retaining a rather broad circulation, which has often resembled the look of a sub-tropical cyclone. Despite the ragged look of Hanna, she has slowly intensified over the previous 12 hours, from a 987mb central pressure, to a 980mb central pressure. Strong convection continues to flare on the western side of the circulation center and now there are some signs that this convection may be attempting to form over the circulation center. Given the decrease in pressure and a continued trend of centrally located convection, Hanna should once again become a hurricane before coming ashore later this evening. Typically, a 980mb pressure would yield a category 1 hurricane but in Hanna’s case, with her broad circulation, this anecdotal rule may not apply. Although one would think the winds would eventually respond to the 7mb drop in pressure. However, I see no reason why Hanna wouldn’t continue to intensify. The moderate shear which has been impacting Hanna may lessen by 5-10kts north of 30°N and Hanna will still have to travel through the Gulf Stream waters, which may give Hanna one final shot in the arm before coming ashore. In addition, Hanna will be moving away from the dry environment to the southeast of the storm. Considering the above, Hurricane Hanna is likely by this afternoon and should be an 80-90mph storm with a 970-975mb pressure before coming ashore between Myrtle Beach and Cape Fear. Hanna is a large storm and will take some time to spin down. It’s quite possible that Hanna remains a hurricane up to 12 hours after landfall, bringing winds of that force over the waters of Pamlico and Albemarle Sounds and adjacent coastal areas, including the Outer Banks. After the circulation center passes north of the Tidewater area winds should slacken to tropical storm force, but winds of this strength will continue up the coast to New England. All coastal areas from Delaware to Cape Cod may see winds up to and exceeding 60mph, which is capable of property damage. Island areas of the Carolinas and Virginia along the Piedmont may see tropical storm force winds as well, especially in gusts. However, this threat lessens in the northern Mid-Atlantic and interior New York/Southern New England, although some of the higher terrain may see stronger winds in gusts as a 40kt low-level southerly jet advances up the coast to the north and east of the circulation center of Hanna. As Hanna makes it ways into the Northeast it will interact with a baroclinic zone and begin its transition into a strong extra-tropical storm that will move to the Canadian Maritimes.

A 4-6’ storm surge should accompany Hanna near the landfall location of the storm. To the south and west of the landfall location storm surge will taper about 1 foot for every 50 miles. The large circulation of Hanna should pile up lots of water along the Southeast Coast ahead of the system, leading to the very gradual drop in surge west of the circulation center. Strong southerly to southeasterly winds to the east of the circulation center will persist as Hanna heads up the coast. This should bring a 2-4’ surge from the Outer Banks to southern New England along south and east facing shores with a 1-2’ surge along north facing shores.

Models project that most of the rainfall associated with Hanna will be along the western side of the storm as it moves up the coast. Hanna will also interact with a baroclinic zone and frontal boundary as it heads into the Northeast, enhancing rainfall amounts there. Along and to the west of Hanna’s track by about 50 miles, rainfall amounts should range from 3-5 inches with local amounts to 8 inches. To the East of Hanna’s track, rainfall should range from 2-3 inches with local amounts of up to 6 inches where feeder bands train over localized areas. There will be a very sharp cut-off to the precipitation amounts on the northwest side of the storm. 25 miles may make the difference between a deluge and passing showers. In addition to the rainfall threat from Hanna itself, a ‘pre’ event may take place in the Northeast, which are notorious flash flood producers. I will have a blog on this potential under my other handle out hopefully later tonight. Should this ‘pre’ event occur, very heavy bands of showers and thunderstorms in a rich tropical airmass will train over localized areas, leading to flash flooding.


Hurricane Ike


Auto-updating IR color enhanced satellite image of Hurricane Ike.


Persistent northerly wind shear is starting to compromise the very small circulation of Hurricane Ike. Currently, hurricane force winds only extend 30 miles away from the center and tropical storm force winds extend less than 100 miles from the center (90mi). In all, only about 175 miles in diameter. As alluded to yesterday, Ike was able to withstand many hours of shear due to its angular momentum, with all the highest winds/uplift located within a very tight inner core. Eventually, the shear degraded the overall structure of the storm as it became asymmetric, exposing the core to greater amounts of shear, which eroded the northern eyewall.

The aforementioned northerly shear, thanks to a strong deep-layer ridge to the northwest of Ike, and the ridge itself is forcing Ike to take a south of due west heading, that he should maintain over the next 24-36 hours; or as long as the ridge to the north of Ike persists. Ike will approach the southeastern Bahamas and the Turks & Caicos Islands very late Saturday night and early Sunday morning. From there models begin to diverge in their tracks, with some continuing the storm on a west-southwesterly course towards Cuba, a handful take it west through the Florida Straits. These tracks are reliant upon the maintenance of a strong ridge to the north of the cyclone as Ike moves west. Other models take Ike towards the southern Florida Peninsula and others keep it just offshore, leaving a threat for those up the East Coast. These models depict a trough moving east across the United States early next week to be deep and strong enough to lift Ike north into Hanna’s wake. In addition, Ike will be making this turn very slowly. More on that below. With four possible scenarios developing in 48-60 hours, residents from Cuba to Canada need to pay attention to the very latest developments on Ike. In addition, a more southerly course towards Cuba or through the Florida Straits would put Gulf Coast residents as risk for an impact from Ike. Currently, a second trough is forecast by models to follow mid to late next week that should be strong enough to sweep Ike into the westerlies. This lessens the chance that Ike would make it as far west as where Gustav came ashore. Most likely, the Florida Panhandle would see Ike as it recurves from the second through in this scenario.

As far as intensity goes, Ike should continue to feel the effects of the strong northerly shear over the next 24-36 hours. It’s likely that Ike will weaken further, to a category 2 storm during this time frame and may even weaken further. As mentioned above, Ike is a very small cyclone and now that it’s structure has been disrupted; it loses some of that ability to fend off such shear. This weakened state of Ike may spare the southeastern Bahamas some of the worst from Ike, but winds of at least hurricane force should affect these islands. After 36 hours the shear over Ike should weaken. Ike will pass the ridge axis to the north and upper winds will turn more from the east lessening their effect on the cyclone. Given that SST’s will be well over 29°C and the surrounding environment will be moistening, a renewed episode of strengthening is possible. These conditions could easily take Ike back to a major hurricane as it approaches either Cuba or Florida. In the long term, should Ike avoid land, retention of major hurricane status is anticipated. Should Ike encounter land, weakening would occur.

Possible impacts from Ike could be catastrophic and widespread. A major hurricane landfall along the southeast coast of Florida, in a highly populated area has great potential for loss of life. Ike will also be passing over the southeastern and central Bahamas, possibly bringing major hurricane force winds to these locations as well. As with any landfalling hurricane, storm surge and wind damage will be determined by the strength of the storm and the center’s proximity to said location with rainfall being determined by its forward speed. However, there are some hidden impacts that are worth looking at. For example, a few models stall Ike over southern Florida. This would dump unbelievable amounts of rain over southern Florida where Fay moved through recently with flooding rains. As South Florida residents know, the situation with Lake Okeechobee and its earthen dam are very precarious. Any lingering of Ike over this area may be a potential disaster. Also, along the East Coast where Hanna makes landfall, some areas may lose power for several days. Should Ike follow on the same course, dissemination of information may be severely compromised. There may be additional flooding down the line from Ike as the cyclone itself or its remnants should take a course up the East Coast mid to late next week where heavy rain from Hanna over the next couple days will prime the region for more flooding.



Tropical Storm Josephine


Auto-updating IR color enhanced satellite image of Tropical Storm Josephine.


I've been holding off on mentioning Josephine for a few days now and thought I'd give the latest info on it.

The 9/5 5pm AST National Hurricane Center advisory puts Tropical Storm Josephine at 16.0°N 35.2°W, or about 725 miles west of the Cape Verde Islands. Josephine is moving towards the northwest at 8mph. Maximum sustained winds are 40mph with a 1004mb estimated central pressure.

A strong upper level low pressure diving into the deep tropics to the northwest of Josephine is causing strong southerly to southwesterly wind shear over the system. This shear has stripped Josephine of all convection and the cyclone now consists of a swirl of low-level clouds. In the low and mid-levels, moderately dry air surrounds Josephine and may limit convection in the near-term. Should Josephine remain devoid of convection through diurnal max, which I doubt, Josephine may degenerate into a remnant low. I fully expect Josephine to give at least one final sign of life and the NHC agrees, keeping her around for the next 5 days.

Should Josephine survive the current hostile conditions oppurtunity for strengthening will occur by the middle of next week as the storm moves towards the open waters of the central Atlantic. Josephine may be one to linger out there for quite some time should it develop further. The pattern over the western Atlantic is likely to remain blocked for at least the next week, limiting the number of strong troughs that would otherwise sweep Josephine into the westerlies.


___________________________________________________________



Current watches, warnings and advisories.


Eastern US current watches/warnings

------


Regional Forecast

Synopsis - Issued 9/5 @ 5:15pm

With much of the focus on Hanna the regional forecast will mainly concern the short-term, including the expected impacts from Hanna. Currently a tropical storm as of the 5pm EDT advisory from the National Hurricane Center, Hanna may very well strengthen into a hurricane before landfall near the North Carolina/South Carolina border. Hanna will then take an inland track through North Carolina and Virginia and emerge off the Jersey Shore Saturday evening, likely remaining a tropical storm. From there, Hanna cross Long Island and skirts by Cape Cod and moves off into the Canadian Martimes Sunday. A swath of rain and wind will affect the areas mainly within 100 miles of the coast. Meanwhile, a trough is approaching western sections with scattered showers and thunderstorms. This trough will link-up with Hanna as it moves away from the region towards the end of the weekend.

Short-term - Issued 9/5 @ 6:15pm

It’s been a fair and warm afternoon for much of the region once again today, aside for a few renegade showers across the Niagara Frontier. One noticeable difference, though, has been the breezy conditions as the pressure gradient over the region increases between the high offshore and Hanna approaching from the south. Clouds will steadily increase tonight as an inverted trough rotates away from Hanna and begins to move into the region. Behind this trough a stronger southeasterly low-level jet will advect a tropical airmass over the coastal plain, as evidenced by precipitable water values progged to approach and exceed 2”. 850mb moisture transport vectors shows a strong surge of lower level moisture moving into the region and a strong theta-e ridge sets-up along a developing coastal front that will also increase low-level forcing over the region. In addition, the Northeast will lie just south, in the right rear entrance region, of a developing 110-140kt jet streak over southern Canada so impressive jet dynamics will also be in place. At mid-levels several lobes of vorticity will ride up along the coastal front/inverted trough, helping to aid in lift and a 40-50kt flow will be developing as Hanna approaches. All this leads me to believe the region should be primed for a “pre” event, or Predecessor Rainfall Event. “Pre” events are heavy convective rainfall events that occur far in advance of a tropical cyclone, by up to 500 miles or more, but are indirectly related to the tropical cyclone itself. These events are characterized by training lines of convective showers and thunderstorms that have the capability of producing 2-3”/hr rainfall rates leading to flash flooding. Expect several lines of these convective showers and storms to develop overnight into Saturday morning over the coastal areas and push slowly inland with the inverted trough. Winds will also increase as the night progresses, especially in locations where the trough moves by. Much of the region will see 10-20mph winds but south of the inverted trough these winds will increase to 20-30mph and become gusty. Over western New York and Pennsylvania clouds and showers will increase as the trough advances towards the area.

Hanna will be rapidly moving towards the Northeast during the day on Saturday, spreading a shield of rain up the coast out ahead of it. The circulation center will reach New Jersey, near the Atlantic City area by late in the afternoon, likely as a tropical storm. Much of the strongest winds with Hanna will be located offshore and along the immediate coast where there’s less friction, but some gusts to tropical storm force may occur over inland sections as well. Hanna begins to bend more towards the east once she reaches 40°N as she rounds the northwestern periphery of the deep-layer ridge over the western Atlantic. This will take the circulation center across central/eastern Long Island and through extreme southeastern Massachusetts overnight Saturday. The rapid movement of Hanna and large circulation center should ensure tropical storm conditions across a wide area within 50 miles of the coast. In addition, heavy rainfall may lead to flooding and saturate the ground to the point where stronger wind gusts may gain the capability to uproot trees and knock out power. Along the coastal regions, higher than normal tides and large battering waves will lead to minor to moderate coastal flooding and moderate to severe beach erosion. There’ll also be a tornado threat along the east and northeast sides of the circulation center.

The wind threat across the Northeast will be minimal. By the time Hanna makes it up to the region the storm will be in a much-weakened state, with much of the strongest winds located offshore. However, this leaves south-facing shore of Long Island right in the path of these winds, along with Cape Cod, Nantucket, Martha’s Vineyard, the south coast of Rhode Island and Connecticut as well as the Jersey shore. Winds may occasionally be sustained at tropical storm force and gusts of 55-65mph are likely. Across inland sections winds will generally be 20-30mph with occasional gusts to tropical storm force. The higher terrain of the Catskills, Poconos, Taconics and Berkshires may see stronger winds due to their elevation. Wind of 50-60mph can down trees, power lines, limbs and branches and can also toss small, unsecured items, such as garbage cans and lawn furniture.

Rainfall will likely be the biggest concern from Hanna, but luckily, the region has seen rather dry conditions over the last couple of weeks. So antedecent conditions are of little concern for a widespread flooding event. Regardless, expected amounts of 4-6 inches with isolated amounts of 8 inches or more could easily cause flooding on their own. This type of rainfall will lead to sharp rises on area main stem rivers, such as the Delaware, Connecticut and Housatonic. However, the main flooding concern will be of the flash flood variety. Even though the ground is dry, the mainly sunny skies have really baked the earth leaving a surface like that of concrete, which could lead to almost immediate run-off. Given that a large amount of rain can fall in a very brief period of time in the ‘pre’ event and with the main slug of rain from Hanna herself, flashy creeks and streams have the potential to quickly flood. Also, low-lying areas and roadside ditches will quickly pond with water. There’ll be a very sharp cut-off to the northwestern shield of rainfall, so 25 miles may separate locations that receive a half inch to locations that receive three inches. Currently, the main band of precipitation is expected fall within 100 miles of the coastline with the western cut-off looking to be on a Scranton-Albany-Concord line.

___________________________________________________________


Radar: Northeast Region Loop

NE radar


___________________________________________________________

Local SST's

Northeast SST's


Current SST's off the Northeast Coast.

Updated: 2:04 PM GMT on September 06, 2008

Permalink

Hanna and Ike; East Coast threats

By: sullivanweather, 1:19 PM GMT on September 04, 2008

Tropical Update

It continues to be a very active tropical Atlantic Basin with three storms stirring the pot. Two of these storms, Hanna and Ike, have a high risk of impacting the United States over the course of the next week. The third, Josephine, is a tropical storm that formed on September 2nd, south of the Cape Verde Islands.


Tropical Storm Hanna


Auto-updating IR color enhanced satellite image of Tropical Storm Hanna.


As per the 9/4 8am EDT National Hurricane Center intermediate advisory, Tropical Storm Hanna was located at 24.1°N 73.1°W, or about 760 miles south-southeast of Wilmington, North Carolina. Hanna is moving towards the northwest at 12mph. Maximum sustained winds are 70mph with a 989mb estimated central pressure.

Hanna has been through a lot and it shows. For days Hanna endured strong northerly shear then was forced south by a deep vertically stacked low that dropped south of Nova Scotia into the western Atlantic. This nearly stripped Hanna of all convection and pushed the storm ashore Hispaniola. With the trough to the north of Hanna finally lifting out, convection re-fired and Hanna began to move back towards the north, then northwest. Overnight, a large influx of dry air moving down the East Coast has become incorporated into the now very large circulation center of Hanna. Devoid of most convection, Hanna now has the look of a large sub-tropical cyclone with most of the wind and rain associated with the system in the northern semicircle of the storm.

Hanna, now having a very broad circulation center, shouldn’t undergo any major strengthening or weakening episodes. The dry air around the circulation is likely to persist but additional flare-ups of convection are likely and some of the dry air should mix out. If enough convection manages to develop close to the circulation center it’s entirely possible for Hanna to reach hurricane status once again. Currently, it’s almost there, just needing an additional 4kt increase of sustained wind speed. Hanna will be steered around the western periphery of a strong deep layer ridge building westward across the western Atlantic. Given that Hanna will spend upwards of 36-42 hours over water before coming ashore near the Cape Fear region of North Carolina overnight Friday or early Saturday morning, I fully expect Hanna to once again become a hurricane, but anything stronger than a cat 1 is unlikely. Hanna won’t spin down fast either, having such a large circulation. It is likely that tropical storm force winds will be felt up the entire coast as Hanna moves up the Piedmont and the coastal plain of the Mid-Atlantic and Northeast Saturday and Sunday.


Hurricane Ike


Auto-updating IR color enhanced satellite image of Hurricane Ike.


As per the 9/4 5am AST National Hurricane Center advisory, Hurricane Ike was located at 22.7°N 55.8°W, or about 550 miles northeast of the northern Leeward Islands. Ike is moving towards the west-northwest at 17mph. Maximum sustained winds are 145mph with a 935mb estimated central pressure.


Hurricane Ike has put on an impressive display of intensification over the last 12 hours, becoming a hurricane at 5pm AST yesterday and a category 4 storm by 5am AST this morning. This was likely due to Ike’s annular structure, being a small symmetrical storm consisting of one main thick band of convection (the eyewall itself). This has allowed Ike to take full advantage of its surrounding environment with inflow into the circulation center unimpeded until reaching the eyewall. This is about to change, however, as the center of Ike continues to gain latitude and head for a zone of confluent flow and light to moderate shear. This is already causing the storm to become asymmetric and given that Ike is such a small storm, it’s likely that Ike will weaken this afternoon back to a category 3.


Microwave image of Hurricane Ike taken last night. Note the strong eyewall of the storm.

As Hanna starts to get a move on to Ike’s east and upper ridging builds north of the cyclone, a west or west-southwest heading should ensue during the day Friday and continue into Saturday. This takes Ike on a course that puts him near 25°N, 70°W in 48-60 hours. The aforementioned upper ridge will place Ike in a sheared environment and after encountering a bit of shear and dry air today, Ike may weaken below major hurricane strength by Friday afternoon or Saturday morning. As mentioned above, the surrounding environment of Ike allowed the cyclone to build a very strong eyewall, which has sustained this rapid intensification. This environment will be breaking down over the next few days, leaving the eyewall more susceptible to intrusions of dry air or bouts of shear. Should the eyewall of Ike become breached, the windfield should rapidly expand and pressure rise. Of note, the shear will be moving with the storm, as opposed to against it. A strong storm may be able to survive 12-18 hours of this type of expected shear, for example, Gustav before coming ashore Cuba. However, longer periods of this shear will eventually compromise the storm, which is what I expect to happen over the next couple days.

Ike will be reaching an area of weaker steering currents by Sunday as it reaches the western periphery of the upper ridge and a trough over the Upper Midwest has yet to reach the system. This will cause Ike to slow down, and possibly expand in size near or just east of the Bahamas. Shear will be weakening as well, so Ike may once again become a major hurricane. Like Floyd in 1999, Ike may get precariously close to the Florida coast, but at this time I feel the trough over the Upper Midwest moving east captures Ike and either sends the storm up the coast, or close enough to the coast to give at least tropical storm conditions to a wide area. Of course there’s other possibilities. For example, the trough may leave Ike behind and high pressure building behind the trough may send it back towards Florida or the trough comes by quicker than anticipated and Ike swings out to sea. But right now the East Coast from the Carolinas on north stand the best chance of seeing Ike in the mind of this forecaster.




___________________________________________________________



Current watches, warnings and advisories.


Eastern US current watches/warnings

------


Regional Forecast


Hopefully today...
___________________________________________________________


Radar: Northeast Region Loop

NE radar


___________________________________________________________

Local SST's

Northeast SST's


Current SST's off the Northeast Coast.

Updated: 1:36 PM GMT on September 04, 2008

Permalink

Hypnotizing tropical Atlantic Basin

By: sullivanweather, 8:49 AM GMT on September 02, 2008

Tropical Update


Updates will be coming as the NHC issues their 5am advisories. We may even have another depression on our hands.


Tropical Storm Gustav


Auto-updating IR color enhanced satellite image of Tropical Storm Gustav.



As per the 9/2 1am CDT National Hurricane Center advisory, Tropical Storm Gustav was located at 31.3°N 90.0°W, or about 30 miles west of the Alexandria, Louisiana. Gustav is moving towards the northwest at 10mph. Maximum sustained winds are 45mph with a 980mb estimated central pressure.

Tropical Storm Gustav will continue to spin down over the next 6-12 hours, becoming a depression during the day on Tuesday. However, heavy rain and isolated tornados within feeder bands will continue over eastern Mississippi, Louisiana, Arkansas, northeast Texas and eastern Oklahoma. Gustav will begin to interact with a frontal boundary later this evening and Wednesday, spreading heavy rain northeastwards into southern Missouri, western Kentucky, southern Illinois and southern Indiana. Additional rainfall over the southern Mississippi Valley to the Arklatex should range from 2-4 inches with isolated 6” amounts. These type of rainfall amounts will spread northeast into southern Missouri, but taper towards Illinois and Indiana to 2-3”, isolated 4”.

It remains to be seen whether the trough will curve the remnant circulation of Gustav into the westerlies or just sweep up most of his moisture, leaving the remnant circulation to spin down over eastern Texas and carried west in the low level flow around high pressure over the Plains. This should become clear today as the cyclone becomes unraveled.



Hurricane Hanna


Auto-updating IR color enhanced satellite image of Hurricane Hanna.


As per the 9/2 5am AST National Hurricane Center advisory, Hurricane Hanna was located at 21.3°N 72.7°W, or about 30 miles east-northeast of Great Inagua Island. Hanna is moving towards the west at 2mph. Maximum sustained winds are 80mph with a 978mb estimated central pressure.



Hurricane Hanna continues to fend off northerly shear over the system, due in part to the outflow of Gustav. This has caused Hanna to sustain 8-12 hour bursts of strong convection (cloud tops routinely –80°C and lower), with minor lulls between flare-ups. The last burst of convection persisted long enough to allow for Hanna to strengthen to a hurricane, but the northerly shear over Hanna has been relentless and may once again weaken Hanna to a tropical storm. Tropical storm or hurricane, I expect the maximum sustained winds to remain between 55-70kts with no major strengthening or weakening episodes over the next 12-24 hours.

A digging trough over the western Atlantic and the continued northerly shear over Hanna may continue to force the storm southwards. Every time Hanna tries to develop vertical structure the northerly flow disrupts the circulation, tilting it towards the south. As the low-level center attempts to locate itself under the circulation aloft, it continues to get forced south which may eventually push Hanna to the shores of the northern coast of Hispaniola. This would obviously throw a big monkey wrench into the equation; especially with the next system approaching fast that may become the headline maker. More on that later. For now, models still indicate that Hanna will start moving northwestwards and eventually north, towards the Southeast Coast from northeast Florida to the Outer Banks. Deep layer ridging is indicated to build west across the Atlantic that would bring Hanna on this path. After rounding the western periphery of the ridge, Hanna would then turn into the westerlies, moving across the Mid-Atlantic into southern New England and offshore. Hanna would reach the coast by Thursday and move across the Piedmont and up the coastal plain Friday and Saturday before moving out to sea.

However, what the models ‘say’ and what’s really happening can be two totally different worlds. Currently, Hanna continues to defy the models and move towards the south, and maybe even southeastwards. Each possibility needs to be strongly considered but after much consideration I’m beginning to think Hanna may commit Atlantic tropical cyclone suicide and tango with the mountainous terrain of Hispaniola. Of course this would be the islands second tropical cyclone hit in a week. In a fleeting note of good news, the storm won’t be hitting the same region of the island, and shadowing helps to decrease rainfall amounts of opposite sides of the island during tropical cyclone landfalls. However, residents of the northern coasts of Haiti and the Dominican Republic need to prepare for a rare landfalling cyclone from the north, whether it’s at minimal hurricane or strong tropical storm strength upon moving ashore. If this solution were to verify it’s impossible to tell what will happen to Hanna. It could dissipate over the island or move west in the low-level trades towards Cuba. Personally, I think it may just give way to Ike.

There’s still much uncertainty revolving around Hanna and any of the above-mentioned solutions has equal chances for happening in the mind of this forecaster.


Tropical Storm Ike


Auto-updating IR color enhanced satellite image of Tropical Storm Ike.


As per the 9/2 5am AST National Hurricane Center advisory, Tropical Storm Ike was located at 18.6°N 43.1°W, or about 1235 miles east of the northern Leeward Islands. Ike is moving towards the west at 15mph. Maximum sustained winds are 50mph with a 1005mb estimated central pressure.


Tropical Storm Ike has developed from the strong tropical wave that moved off Africa late last week. This wave was expected to develop a week in advance by global models and lived true to form, developing into a cyclone and becoming the 9th named storm of the 2008 Atlantic hurricane season.

Banding features had been quite evident on satellite with Ike, but coming out of the eclipse period Ike has now developed a nice core of convection around the center of circulation, which currently looks to be taking more of a west-northwesterly jog. This appears to be in response to the large-scale flow being from more of a southeasterly direction on the east side of an area of frontogenesis extending between Ike and old 98L to the northwest and being on the southwest side of a building deep layer ridge to the north of the cyclone. The old 98L had interacted with an upper level disturbance and developed sub-tropical features, leaving a weakness in the path ahead of Ike. However, this system is now moving away rapidly, caught in the westelies and should be of little concern to Ike in 12-24 hours. The ridge building to the north of Ike should steer the cyclone on a west to west-northwestward path over the course of the next 5 days, putting the system precariously close to the Southeast Coast and Bahamas once again.

Upper level winds over Ike are light and anti-cyclonic. Some dry air exists to the north of Ike but within the immediate vicinity of the cyclone a lack of moisture is not a problem. Sea surface temperatures along the expected path of Ike are very warm, currently near 28°C and should warm to near 29°C as the storm heads into the western Atlantic. Overall conditions are expected to change very little over the next 5 days so continued strengthening of Ike is expected. Ike is expected to become a hurricane over the next 18-36 hours and may continue to strengthen into a major hurricane in 3 days with intensity fluctuations thereafter being controlled by the internal structure of the storm. There’s lots of time to watch Ike and with all the activity in the western Atlantic ongoing, residents are surely perked to the latest in the tropics and likely preparing for Hanna, whether or not she comes.





___________________________________________________________



Current watches, warnings and advisories.


Eastern US current watches/warnings

------


Regional Forecast


Coming later...
___________________________________________________________


Radar: Northeast Region Loop

NE radar


___________________________________________________________

Local SST's

Northeast SST's


Current SST's off the Northeast Coast.



___________________________________________________________


August Daily Weather Statistics

August 1st - 79°F/57°F....0.00"....60%
August 2nd - 75°F/59°F....0.52"....40%
August 3rd - 75°F/55°F....0.09"....50%
August 4th - 76°F/57°F....0.00"....75%
August 5th - 80°F/55°F....0.00"....60%
August 6th - 80°F/64°F....0.71"....30%
August 7th - 77°F/57°F....0.03"....40%
August 8th - 71°F/57°F....0.07"....30%
August 9th - 76°F/55°F....0.00"....70%
August 10th - 68°F/52°F....0.32"....15%
August 11th - 64°F/57°F....0.11"....10%
August 12th - 72°F/59°F....0.23"....40%
August 13th - 73°F/50°F....0.00"....65%
August 14th - 79°F/60°F....0.30"....60%
August 15th - 71°F/57°F....0.03"....20%
August 16th - 73°F/55°F....0.04"....60%
August 17th - 78°F/50°F....0.00"....80%
August 18th - 80°F/55°F....0.00"....80%
August 19th - 71°F/51°F....0.26"....40%
August 20th - 72°F/43°F....0.00"....100%
August 21st - 78°F/46°F....0.00"....100%
August 22nd - 81°F/54°F....0.00"....95%
August 23rd - 79°F/52°F....0.00"....80%
August 24th - 81°F/58°F....0.00"....40%
August 25th - 75°F/60°F....0.19"....40%
August 26th - 73°F/45°F....0.00"....90%
August 27th - 73°F/46°F....0.00"....90%
August 28th - 76°F/50°F....0.00"....50%


Updated: 9:07 AM GMT on September 02, 2008

Permalink

About sullivanweather

Thomas is an avid weather enthusiast, landscaper and organic gardener. This blog is dedicated to Northeast and tropical weather forecasting. Enjoy!

Local Weather

Clear
30 °F
Clear

sullivanweather's Recent Photos

Sully
Coronas
Mid-October snowfall
Mid-October snowfall

Personal Weather Stations

Barryville, NY
Elevation: 1012 ft
Temperature: 15.1 °F
Dew Point: 11.4 °F
Humidity: 85%
Wind: Calm
Wind Gust: 4.0 mph
Updated: 11:55 PM EST on February 17, 2014
Town of Lumberland
Glen Spey, NY
Elevation: 1326 ft
Temperature: 58.2 °F
Dew Point: 55.9 °F
Humidity: 92%
Wind: Calm
Wind Gust: 0.0 mph
Updated: 6:01 AM EDT on June 09, 2014

About Personal Weather Stations