Thomas is an avid weather enthusiast, landscaper and organic gardener. This blog is dedicated to Northeast and tropical weather forecasting. Enjoy!
By: sullivanweather , 8:08 AM GMT on December 30, 2008
Current watches, warnings and advisories.
Synopsis - Issued 12/30 @3:05am
Several areas of low pressure will move along a very fast west-east flow across the northern tier of the country into the Northeast. The first in this series of clippers is moving through the region at the time of this writing. The next, and most potent, will slide by Tuesday night and Wednesday, followed by another on Friday/Saturday and a fourth on Sunday.
Short-term - Issued 12/30 @3:05am
Snow showers and flurries had overspread much of the northern half of the Northeast as of late Monday evening in association with a rather potent clipper low moving across southern Canada. This system is moisture starved and would hardly be considered ‘potent’ in terms of accumulating snowfall, however, where it will be felt most is in the wind department. Flow at 850mb is in excess of 50kts across a good chunk of real estate with a strong 35-45kt boundary layer flow aligned out of the west-northwest. Given the strong cold air advection behind the cold front trailing south from the low center these winds should easily mix down to the surface and wind advisories have been posted just about region-wide, aside from Maine lying just outside of the belt of strongest winds located to the southwest. Combined with the light to, at times, moderate snow across upstate New York and northern New England traveling will become quite difficult, with occasional near-zero visibilities in blowing snow, especially across the higher terrain of the Adirondacks, Green and White Mountains. Also included are areas immediately downwind of Lake Ontario as the lake effect kicks in. This is where the accumulating snow will be found, on the order of 2-4” with less than an inch elsewhere across the region. Temperatures tonight are holding steady now that clouds have overspread much of the region but they will fall towards daybreak as deeper cold air moves in.
Much more of the same on Tuesday in terms of strong winds and lake effect/terrain enhanced snow showers. The clipper will transfer its energy to an area of cyclogenesis east of Newfoundland leaving behind little forcing outside of local enhancements and general cyclonic flow. Upslope areas of the North Country and around the Tug Hill Plateau should receive an additional inch or two of wind-driven snow. For most everyone else the skies will be partly cloudy but the big story will be the winds. Boundary layer flow will still be 30-45kts from I-81 on east across eastern New York and much of New England. Continued cold air advection and diurnal influences will drive these winds down to the surface in gusts that may very well exceed 50mph, especially in exposed/elevated areas. Temperatures will rise very little during the morning hours and will likely fall several degrees during the afternoon as the airmass aloft cools roughly 4-6°C through the course of the day. Highs will reach the upper 30’s to low 40’s along the southern coastal plain with upper 20’s to mid 30’s across the interior and along the northern New England coast. The higher terrain will likely see an all day drop in temperatures, beginning the day in the mid to upper 20’s then dropping to the upper teens by day’s end. There will be an increase in high cloudiness late in the day across the western portions of the region as isentropic lift ensues ahead of the next disturbance. A good time to keep an eye to the sky for sun pillars/sun dogs, always a winter sky treat. If these clouds move in early enough, before 2pm when the sun is at a high enough angle, a circumzenithal arc may be witnessed or other intriguing sun halos.
As night falls clouds will rapidly increase from the west, lowering and thickening during the evening hours. Light snow will break out by midnight across the Niagara Frontier and extreme northwestern Pennsylvania around midnight, spreading eastwards to cover much of the Finger Lakes region, Catskills, Allegheny’s and the northern tier of Pennsylvania by daybreak. Thereafter it will spread across southern/central New England during the day on Wednesday. The surface low looks to take a track from the Upper Ohio Valley and across southern Pennsylvania, with surface low reformation occurring just off the northern New Jersey Coast. As the low tracks across the region it will be deepening rapidly. Pressure falls from ~1002mb when it enters the region to ~988mb as it passes south of Cape Cod. Despite not having much moisture to work with (Precipitable water values around .25-.33”) strong frontogenic forcing along the north side of the tracks of the 850/700mb low couplet will make for very efficient precipitation generation. Also, unlike previous storms this season, strong UVM in the snow growth region (-15 to -20 microbars/sec) will make for increased fluff factor, leading to 15-18:1 snow:liquid ratios, especially in the axis of strongest frontogenesis, though, where this intersects with the immediate coast ratios will likely be lower due to warmer temps in the boundary layer, likely 10:1. Strongest model projected 2-D frontogenesis occurs along the New York/Pennsylvania border to the southern Catskills/Taconics and along the I-84 Corridor across southern New England. Model QPF has steadily increase in the lead up to this event and is now running around a third to a half an inch, with lesser amounts (<.25”) to the north and south of axis of heaviest precipitation. The southern cut-off should lie across the southern tier of Pennsylvania across to Atlantic City, New Jersey, where just a few scattered flurries and/or sprinkles will fall. To the north, the northern edge of the precipitation lines up from the southern Adirondacks eastwards to the Portland, Maine vicinity. A snow map will follow shortly to outline amounts, which should range from 4-8” across the area progged to receive the highest QPF. Lows Tuesday night will range from the teens and single digits across the far north to the 20’s and low 30’s across the southern interior and coastal plain. On Wednesday, temperatures remain steady or slowly fall across the south as arctic air pours into the region behind the departing low while across the north temperatures rise into the 20’s by noon and drop sharply by mid afternoon thanks to the arctic airmass. Winds will also become quite blustery once again thanks to aforementioned pressure falls and strong cold air advection.
Mid/long-term - Issued 12/30 @6:15am
Low pressure rapidly pulls towards Newfoundland Wednesday night as it bombs out to a 975mb storm center. Strong cold air advection will be left in its wake as 850mb temps drop from –15°C to –24°C, ushered in on a gusty north-northwesterly flow. Airmass is also very dry and given the short fetch, lake effect snows will be kept to a minimum, likely a multi-band event across central New York. There may even be a few ocean effect bands out over the Cape. Despite the overall lack of precipitation, with the very cold airmass in place and gusty winds over a fresh snow cover there will still be a host of problems to deal with. Lots of folks will be out and about due to the New Year’s holiday and it would be a good idea to pack a winter weather survival kit. On their own, temperatures will be very cold across the region, ranging from the upper teens to low 20’s along the coast, but inland it’ll be much worse. Here temperatures should fall into the single digits with the North Country likely falling below zero, by a good margin across the higher terrain too. In addition, the biting wind of 10-20mph will create wind chills close to zero along the coast and up to –30°F across the far northern interior. These winds will also create lots of blowing and drifting of snow. It may be a good idea to simply keep it indoors for New Year’s Eve this year. Ouch!
High pressure builds in on Thursday (New Year’s Day) with a slackening of the winds and a slight moderation of the brutal airmass overhead, except for over Maine where 850mb temps should fail to climb out of the –20°C range. Skies will become mostly sunny but temperatures at the surface will fail to respond to the weak January sun with highs running some 5-15 degrees below normal. The high will crest over the Northeast Thursday night with excellent radiational cooling conditions. Many locations across the northern interior will once again fall below zero with the remainder of the region in the single digits and teens.
The next system of concern moves towards the Northeast on Friday. Still much to be resolved with this one as the main pocket of energy still lies in the Gulf of Alaska. Recent model trends have been for a much less amplified storm and a lack of phasing with southern stream energy until it’s mainly east of the region. GFS remains steadfast in developing low pressure in the Delmarva vicinity Friday and moving it up the coast for a significant snowfall for the eastern half of the region into the first half of the weekend but other model solutions have trended away from this scenario and now depict more of a northern stream trough passage with cyclogenesis occurring south of Nova Scotia. As it looks currently, Maine stands the best chance at a significant snowfall with mainly light accumulations of snow all points west. Until this energy moves ashore the Pacific Northwest and comes under a better sampling from ob sites uncertainty will remain high. A weak transient ridge clears things out from west to east Saturday into Saturday night, though it will be blustery before this high arrives, then the next system moves in by Sunday afternoon spreading more snow showers to the north with a light mix or rain showers to the south.
Looking ahead into next week, a southern stream disturbance looks to make a run at the Northeast by next Tuesday. This one should have much more moisture to deal with than any of the first 4 systems to affect the region over the next 7 days and will be one to watch.
Radar: Northeast Region Loop
Ferndale, NY climagraph
***Climagraph has been discontinued and will return at the beginning of 2009 with the location of Yulan, NY***
2008-09 Winter Forecast
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