Thomas is an avid weather enthusiast, landscaper and organic gardener. This blog is dedicated to Northeast and tropical weather forecasting. Enjoy!
By: sullivanweather , 12:35 PM GMT on November 04, 2012
Current watches, warnings and advisories.
Current watches, warning and advisories issued by the National Weather Service. Courtesy of NOAA.
East Coast IR satellite image.
Highly meridional flow pattern over the North Atlantic will have huge implications on the sensible weather here in the Northeast for the upcoming week. Broad cyclonic flow will round out the weekend as one last disturbance rounds the upper level remnants of Sandy delivering a reinforcing shot of colder air, likely the coldest of the season for most Northeast locales to start the new week. High pressure briefly moves through the region on Tuesday yielding a clear but rather chilly day before the next major system sets a course for the region. Two disturbances in the northern branch of the jet will phase off the coast resulting in a rather intense early-season nor'easter. Due to the recent passage of Sandy and the compromised shoreline protections against surge, the coastal flooding threat will be greatly enhanced. Due to the expected intensity of the storm working in tandem with a moderately-strong surface high pressure over Quebec, high winds will once again be a concern. Additionally, indications are of a widespread accumulating snowfall across many locations across the western interior with heavy rain along the coast and for the eastern interior. This storm will slowly lift northeast off the coast on Thursday and Friday, with a brisk northwest wind in its wake and a developing confluent flow aloft as the pattern remains blocked downstream. Far in the extended, a strong low pressure system should develop over the High Plains over the weekend and head northeast into Canada, well northwest of the region. This will spread an increasingly mild airmass into the Northeast, save perhaps one weak backdoor front, from next weekend into the beginning of the following week, however, the cold front spawned from the Plains storm will head east and become increasingly anafrontal. This may spell a rain to snow scenario for locations inland of the coast and yet another 1"+ rainfall event along the coast.
A weak shortwave is working across the Northeast this morning providing for some flurries across central New York and northeast Pennsylvania, aided slightly by some lake enhancement. Areas southeast of Syracuse may see a dusting by morning. Otherwise most Northeasterners will wake up to mostly clear skies and a continued chilly northwesterly breeze. Temperatures will start the day mainly in the 30's across the interior with low 40's along the coast. Bright sunshine along the coastal plain will have little warming effect today with weak cold air advection and a stiffening northwest breeze. Expect highs to reach close to 50 in these locales. highs in the 40's will be common across the bulk of the interior as afternoon skies become partly cloudy. Some of the higher elevation areas of the North Country will be held in the 30's. Skies will clear toward evening, now in the four-O'clock hour, winds will die down and temperatures will swiftly drop with most coastal locales set for their coldest night of the season. Much of the interior will drop into the 20's tonight with some upper teens across the higher elevations. Along the coastal plain temperatures will drop to around freezing while the heart of the urban areas fall to the mid to upper 30's.
There'll be frost on the pumpkin as the sun rises on Monday, a chilly precursor for what's to come later in the week. Sunny skies will greet most of the communities getting back to normal life on Monday, as it will be the first day of school/work since October 26th for many of the moderately affected. Once again, despite the bright sunshine, the air will have a definite chill and temperatures will only climb into the 40's for much of the Northeast, with 30's across the higher terrain. A tightly wound mid/upper-level low pressure will drop south out into Quebec as the day progresses with its associated cold pool of air aloft settling over the Northeast region. This feature will provide some mid/high clouds across the North Country and maybe a stray flurry or two but nothing more. Winds will once again be out of the northwest around 10-15mph.
High pressure quickly builds over the region Monday night, yielding clear skies and calm winds. 850mb temps progged to range from -4°C to -12°C south to north. This should easily be the coldest night yet this season for most locations across the Northeast. Teens in the higher elevations with low to mid 20's across the interior; upper 20's to around 30 along the coastal plain. Even the urban centers may approach the freezing mark by daybreak Tuesday morning. For many still without power the freezing temperatures will be of particular concern. Also of note, these temperatures will end the growing season in areas yet to receive a killing freeze.
With high pressure cresting over the region on Tuesday morning sunny skies are once again expected to start the day. Temperatures will be quite similar to those of Monday, though with less wind, so the chilliness won't have the same bite. Keep in mind these are the coldest temperatures many of us will have seen since before the March heat wave so the cold is probably going to take some getting used to. Some high clouds will begin to spill north ahead of the next big weather-maker during the late afternoon hours across southern Pennsylvania and New Jersey. These high clouds will continue to spread north and thicken Tuesday night into Wednesday morning as low pressure gathers strength off the Carolina coast. From this point forward model guidance diverges on strength of low pressure, timing, track, etc.; as if there ever wasn't a fickle nor'easter.
The primary disturbance which will spawn the upcoming nor'easter is currently spinning down into the Heartland of the country, meanwhile, the secondary disturbance which will provide the final piece of energy to really make this nor'easter explode still resides along the northern coast of British Columbia. Though barely represented in surface pressure fields, at mid/upper levels the primary disturbance is a rather vigorous one, with a stripe of 40-60dm 12-hour 500mb height falls along the track of the low across the central Plains. The disturbance will continue to round the base of the trough Monday into Tuesday, reaching the warm Gulf Stream waters offshore the Georgia Coast Tuesday afternoon. As the upper level feature meets those very warm waters expect an explosion of strong convection along an offshore coastal front and the rapid development of surface low pressure just east of Savannah which will then track northeast. Global models usually underestimate the strength of such convective blowups when such vigorous systems reach the coast, typically due to their poor resolution. As an effect there's less downstream ridging represented is these models, often presenting track solutions further to the east than what usually ends up occurring. This is a trend we have seen in model guidance over the last several runs as there's been a slight eastward shift in storm track in a plurality of the global models. However, the higher resolution ECMWF and UKMET models continue to show a track closer to the coast and it seems prudent to primarily follow the guidance of these two models with some adjustments, of course.
Tuesday night low pressure deepens rapidly off the Southeast coast, going from roughly 1010mb at 5pm Tuesday to 990mb by 5am Wednesday. By Wednesday morning the secondary piece of energy will dip down the backside of the longwave trough, which will begin taking on a negative tilt, furthering the intensification process of the nor'easter and dropping the pressure of the surface low to about 980mb as it moves 50-75 miles offshore the Delmarva Peninsula and occludes Wednesday night/Thursday morning. Far to the north, a 1035mb area of high pressure centered of Labrador will yield little ground, making for a tightening the pressure gradient over the Northeast region of the country resulting in yet another strong wind event; more on that to come. As it appears currently, 980mb will be the peak intensity of the low pressure as it wraps up off Cape May early Thursday. Thereafter, low pressure will start to pull east-northeast away from the coast and weaken through Friday. On to the particulars...
Clouds will continue spreading north Wednesday, lowering and thickening as the day progresses. Due to the slower track of the storm it now appears precipitation won't reach the region until mid-morning at the earliest for coastal sections of southern New Jersey, with a more likely start time closer to the noon hour. The shield of precipitation will steadily advance northwestward, reaching Philadelphia by mid-afternoon and New York City by dusk. Along the northern and western fringes of the precipitation shield, a wintry mix or just plain snow will commence due to dynamic cooling of the column. Given the current expected track of the low pressure and placement of the colder air, areas just northwest of I-95 from Washington to Philadelphia will be the first to changeover early Wednesday evening. Further to the north and west, precipitation will begin Wednesday evening in the form of snow from Harrisburg to Scranton to Springfield, Massachusetts. The snow will be heavy at times and quite wet, accumulating 1-2"/3hr, slightly more at higher elevations. As the onshore flow brings milder air in from the east across southern New England and as far west as the Hudson Valley, expect a changeover to rain, or even freezing rain at higher elevation areas such as the Berkshires and Litchfield Hills. While areas north of the low change to rain, locations west of the low will be changing to snow as colder air circulates into the backside of the low pressure. This means Washington and maybe even areas as far south as Richmond may very well see their first accumulating snowfalls of the season.
By midnight Wednesday night/Thursday morning the storm will really be cranking, with a large arc of snow, possibly reaching the Tidewater of Virginia all the way to the coast of southern Maine, falling locally heavy at times combined with the stiff northeasterly wind will make for near-blizzard conditions. Along the coastal plain from New Jersey to southern New England a windswept heavy rain will make for a miserable night, especially for those still without power when the storm arrives. This rain will taper to scattered showers and drizzle by Thursday morning. The precipitation shield will have a sharp cutoff along the northwest flank of the storm. Areas west of a line extending from the Laurel Highlands to the western Finger Lakes region to the Tug Hill Plateau will see little, if any, precipitation and if any does fall it will likely do so as rain with marginal boundary layer temperatures and very light precipitation rates. Snow will continue to spread north into northern New York and northern New England the remainder of the overnight hours into Thursday morning. As the best forcing slowly abates and moves north into Canada snowfall rates will come down and snow will end as a period of light rain or drizzle from eastern Virginia northward to central New York. Light to occasionally moderate snow will persist in northwestern Maine, northern New Hampshire and northern Vermont through the rest of Thursday afternoon before tapering to snow showers Thursday night over the Adirondacks and Green Mountains. Rainfall amounts along the coast will range from three-quarters of an inch to two inches. Enough to cause ponding of water on roads and parking lots but most of this will be nuisance flooding and not anything particularly worrisome. Inland areas which receive snowfall the forecast is a bit more tricky as precipitation rate and elevation will be key with these early-season event. Areas best slated to see accumulations of six inches or more are the ridgetops of central Virginia north to central/eastern Pennsylvania, the Poconos, the Catskills and the higher terrain of the North Country. Lowland areas under the deformation axis may also see a solid 2-4 inches with isolated amounts of up to six inches; this includes the metro areas of Washington and Richmond, as well as several mid-sized cities across the interior including Harrisburg, Scranton and Binghamton.
Wind and surge will play a significant role with this nor'easter, despite being just your basic package nor'easter, the reason being Sandy which roared ashore last week. Trees have been weakened and shorelines have been decimated in the wake of Sandy, leaving many vulnerabilities. Coastal communities have had precious dune protections washed away and seawalls have been breached at various points along the Jersey Shore and Long Island. Although this upcoming nor'easter is expected to bring only a 1.5-3' surge along the coast, with the aforementioned protections gone this will allow for another round of minor to moderate coastal flooding. One saving grace with the storm is that it will be moving away from the coast, as opposed to coming ashore. This will mean a switch in wind direction midway through the storm to an angle more oblique to the coastline. This will spare many areas a second high tide of direct onshore winds. These winds will begin to pick up early morning on Wednesday out of the east-northeast at 20-30mph along the coast (10-20mph inland), then become northeasterly and increase to 25-40mph with gusts to 55mph (15-30mph with gusts to 40mph inland) by afternoon. These winds continue into Wednesday night and take on a more northerly component before slackening by Thursday morning as low pressure stops intensifying and pulls away from the coast. With winds of these speeds (especially in areas which receive snowfall) additional power outages are likely. Also of note, with winds expected to be of such strength utility crews will likely be pulled off their jobs as the storm passes through. So in areas still without power when the storm hits this may add another 24-36 hour delay to restoration times.
Expected wind speeds for upcoming nor'easter
Expected snowfall for upcoming nor'easter
Radar: Northeast Region Loop
Radar loop of the Northeast region. Courtesy of Weather Underground.
Sea-surface temperatures off the Northeast Coast. Courtesy of NOAA. (unavailable until NWS Eastern Region communications blackout is resolved)
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