Thomas is an avid weather enthusiast, landscaper and organic gardener. This blog is dedicated to Northeast and tropical weather forecasting. Enjoy!
By: sullivanweather , 10:38 AM GMT on August 18, 2008
Warnings, advisories and storm reports during the previous 72 hours. Click on map to view individual reports.
Current watches, warnings and advisories.
Synopsis - Issued 8/18 @6:30am
A vigorous shortwave trough will move across Ontario and Quebec on Monday and Tuesday, dropping a strong cold front into the Northeast. Showers and thunderstorms will accompany the frontal passage and much cooler air will filter in behind it. Surface high pressure settles over the region Tuesday night delivering a very chilly late summer night. This high will slowly translate offshore by Thursday as heights build aloft and temperatures moderate. By Friday into the weekend the heat and humidity builds to mid summer-like readings with chances for convection increasing by Saturday night and especially Sunday and Monday as the next trough approaches.
Short-term - Issued 8/18 @6:30am
A lone thundershower over Lake Erie may come ashore along the Pennsylvania-New York border early this morning but as for everyone else Monday should begin as a fine day with mostly sunny skies. Some patchy valley fog will be present but should quickly burn off by mid morning. Temperatures should rise rather quickly into the upper 70’s to mid 80’s by noon under nearly full sun, 12-16°C 850mb temps and mixing to about that level. A few locations may top out near 90°F across the urban corridor of New Jersey with some downsloping. Most other locales outside of the higher terrin will top out in the 80’s. Meanwhile, a sharp trough over Ontario will send a strong cold front towards the region. Areas along the US-Canadian border will be in the right rear entrance region of a developing 90-100kt jet streak @300mb over Quebec. Upper divergence will enhance the broad scale ascent ahead of the approaching trough, thanks in part to a strong shot of PVA. At the surface, moisture pooling ahead of the front combined with the warm airmass over the region will push surface based CAPE values over 1,000J/kg. Surface frontal boundary will initiate storms over Canada during the afternoon hours and slide southeastwards towards the US side of the border by evening. In addition, height falls eroding the northern and western flank of the cap over the region will allow storms to develop over the higher terrain and move eastwards. Winds aloft will increase dramatically during the course of the day. Strong unidirectional flow increases to 40-60kts @500mb, 30-40kts at 850mb by evening. Storms will easily be able to transfer these strong winds to the surface. Initial formation of storms should be cellular in nature but as evening approaches bulk shear will rise to 30-35kts so storms will organize into bowing line segments, especially along the actual cold front. Precipitable water values will range from 1.25-1.5” so any training or back-building of storms may result in flash flooding. Drier times over the past couple days has allowed more of a cushion to flash flooding over New England but the soil still remains wet. The cold front continues southeastward into the region during the overnight as storms weaken with the loss of heating. The warm moist airmass ahead of the front combined with cloud cover will hold up temperatures in the 70’s for the most part. Along and behind the front, precipitation will cool things into the 50’s and low 60’s. Some clearing will occur late that may push temperatures along the US-Canadian border down into the 40’s. A cool crisp breeze will follow in behind the front.
The front continues through the region on Tuesday without the same fanfare as today as the upper support for the system moves well northeast of the region towards the Davis Strait. Some scattered showers and maybe a rumble of thunder will be all that’s left of the front as it clears the southern half of the region. Elsewhere it will be cooler and much less humid. 850mb temps fall all the way down to 2°C over northern Maine with the 10°C isotherm south of the New York-Pennsylvania border. A refreshing, dry northwesterly breeze will give the day an early autumn feel. Some cumulus clouds will dot the region with the greatest concentration of cloud cover over the higher terrain of northern New York and New England. It wouldn’t be surprising if a few of these cumulus clouds produce a few sprinkles or a brief heavier shower, but these will be few and far between. There will be a sharp temperature gradient across the Northeast as areas south of the front climb into the 80’s, but towards the north temperatures will range from the low 60’s to low 70’s. Some locales across the higher terrain may just remain in the 50’s! Surface high begins to build into the Northeast Tuesday night, bringing clearing skies and light winds, aside from Maine. A good night for radiational cooling, temperatures are likely to plummet into the 40’s and 50’s. It may even dip into the 30’s across sheltered valleys in the Adirondacks and may very well be chilly enough for frost if the atmosphere is able to decouple early enough in the overnight. A great night for campfires!
Mid-term - Issued 8/18 @6:30am
The surface high crests over the Northeast on Wednesday as upper heights begin to build. This will be the first day of a moderating trend that will take temperatures back to normal means by Friday. Afternoon highs are likely to approach average by Thursday but overnight lows will remain below normal until Friday with a drier airmass over the region and lengthening night. It should remain dry throughout the mid-term (Wednesday-Friday).
Long-term - Issued 8/18 @6:30am
Deep layer ridge will be over the Northeast this weekend as increasing southerly flow begins to pump increased humidity levels into an already warm airmass. 850mb temps rise to 14-17°C on Saturday and Sunday, pushing surface temperatures back towards mid-summer readings. With the increase in heat and humidity, diurnal convection will begin to be a concern, although the lack of any synoptic triggers will make for mainly isolated activity, likely terrain enhanced, outflow boundary type pulse storms. A trough will begin to approach by Sunday night and Monday that should lead to a higher concentration of activity although it is still too early to tell whether or not any severe weather will occur with the feature. This trough will also bring an end to the brief return of summer.
Tropical Storm Fay
At 5:00AM EDT the center of Tropical Storm Fay was located at 25.9°N, 81.7°W along the Florida coast at Cape Romano, about 55 miles south of Fort Myers, Florida. Fay is moving towards the north-northeast around 9mph with a continuation of this heading and forward speed expected today. Maximum sustained winds are around 60mpg with higher gusts. Minimum pressure reported by reconiassance aircraft is near 989mb.
Fay’s appearance has improved over the previous 6 hours or so with the cyclone now having a well-defined CDO with the center of circulation now developing a partial eyewall on the northern semi-circle. Outflow remains poor in the southern and western quadrants but good to excellent in the northern and eastern quadrants. There’s not much time for Fay to strengthen into a hurricane, however, with the center of circulation now coming ashore. Once Fay does move ashore the cyclone should steadily weaken. In about 18-24 hours the center of Fay, whether still a tropical storm or downgraded to a depression, should emerge off the east coast of Florida over the open waters of the Atlantic. From there there’s a small window for re-strengthening to occur but the cyclone is not likely to attain hurricane strength before moving back ashore the Space Coast in 48-60 hours. In all, the cyclone stands very little chance to become a hurricane over the next three days.
The track of Fay becomes highly uncertain after 60-72 hours. A strong mid-latitude deep layer ridge will develop to the north of the cyclone following the passage of a strong cold frontal boundary that will be moving off the East Coast north of the Mason-Dixon line over the next 24 hours. The development of this high will likely slow and/or stall the cyclone either just off the east coast of Florida or just inland of the coast, halting its northward movement. Where Fay moves from there is anyone’s guess as several possibilities arise. It is possible that the high will influence a westward turn to Fay, pushing the storm across the Florida peninsula and back over the northeastern Gulf of Mexico where it will have the potential to re-strengthen, becoming a threat to the east side of the northern Gulf Coast. From there a trough dropping into the Midwest late in the week would likely pick up the storm and accelerate it to the northeast as it undergoes extra-tropical transition. Another possibility has the high not as prominent in the cyclones’ future track as Fay will still bend back towards the west but with a more northerly component. This would prevent the storm from emerging back out over the Gulf of Mexico and keep it inland over northern Florida or southern Georgia where Fay would likely become a remnant low. The good news from either scenario would be more beneficial rainfall to the Southeast as they struggle to come out of the grips of a prolonged drought.
Fay isn’t the only game in town now as a strong tropical wave with an area of low pressure along its axis (94L) is showing signs of becoming a tropical depression. The center of the low pressure is located close to 12.5°N, 36.5°W moving towards the west around 8-10kts. Overnight, convection has become consolidated around the center of circulation and the only factor likely preventing this strong disturbance from being named a depression at 5am is persistence. However, I fully expect this disturbance to be named a depression and become the next named storm over the next 18-36 hours, as environmental conditions are favorable for further development. On a side note, the blow-up of convection east of the disturbance could become the next area of interest in the coming days.
The track of this disturbance will likely be just north of due west over the next 24-48 hours then hedge more towards the west-northwest or northwest as a weakness develops in the deep layer ridge to the north of the disturbance/potential cyclone upon reaching 50-55°W. Southwesterly wind shear may become detrimental to development beyond 72 hours as an upper trough axis is progged by models to be over the eastern Caribbean at that time. Whether or not this shear will rip apart the system, assuming it develops, or further hinders development, assuming it doesn’t, is unknown this far in the future. However, the projected moderate to high shear environment will at least slow down or halt the development of this system for some time. In the long range (beyond 5 days time) the deep layer sub-tropical ridge bridging the Atlantic looks to re-establish itself, which could potentially spell trouble for land areas to the west as easterlies expand across the Atlantic basin south of 25°N.
Radar: Northeast Region Loop
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%
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