Northeast Weather Blog

Current watches, warnings and advisories.




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Forecast Discussion



Synopsis - Issued 11/29 @1:45am


Weak high pressure builds over the Northeast on Saturday, providing a fair day for most outside of a few lake effect flurries. On Sunday, a complex double-barrel low pressure system will develop over the Southeast and push towards the region bringing widespread rain to the coast, with a mix or snow to the interior lasting into Monday. It will be fair for Tuesday and most of Wednesday before a strong cold front brings a return to winter-like weather by Thursday.


Near-term - Issued 11/29 @1:45am


Very localized heavy lake effect snow will be winding down across the Tug Hill Plateau during the overnight and into the early morning hours on Saturday. Several more inches of snow may accumulate on top of the quick 4-8” burst seen Friday afternoon/evening. A few snow showers have also pushed off Lake Erie into central New York but these will leave a dusting at most. Temperatures will begin the day in the 20’s across the interior with 30’s along the coastal plain.


Short-term - Issued 11/29 @1:45am



With high pressure, albeit weak, building over the region on Saturday there should be fair skies for most with light and variable breezes. High temperatures will be tolerable, with highs in the 30’s across the interior and 40’s along the coastal plain, right on cue for the end of November. High clouds will begin to filter in from the south during the late afternoon and evening hours, thickening and lowering during the overnight. A few light flurries (interior) and sprinkles (coast) should cross the Mason-Dixon line after midnight but should remain confined to south of the I-78 corridor. Lows will be in the teens and 20’s across the north with upper 20’s to mid 30’s across the south and along the immediate coast. Winds will begin to shift from the east around 5-10mph.

A very complex set up on Sunday thanks to a series of disturbances dropping into the upper trough over the Mississippi Valley region. This will help to sharpen and deepen the trough over the Mid-Mississippi Valley region as the northern stream disturbances provide support for cyclogenesis over the Tennessee Valley. In addition, several areas of low pressure will develop along a quasi-stationary boundary aligned from the Florida panhandle to the Outer Banks of North Carolina, as they fight to become the secondary low. In response to this deepening trough, heights will build over the western Atlantic with a strong southwesterly jet developing over the eastern US helping to transport moist, mild southerly air up the coast. The aforementioned weak high pressure that will bring fair weather to the region on Saturday won’t put up much of a fight to the advancing low as it marches northeastwards, meaning the cold air over the region now will be transient in nature. Initial batch of precipitation will overspread most of Pennsylvania, New Jersey, the southern half of New York and southern New England during the day on Sunday thanks to strong theta-e advection. Across most of the interior above 1,000’, temperatures aloft and in the boundary layer, as well as partial thicknesses, indicate that precipitation type will be in the form of snow. At lower elevations rain will mix in with the snow as the boundary layer warms into the mid and upper 30’s. There’s a low threat for freezing rain in some of the deeper valleys of central Pennsylvania, right along the east side of the Appalachians. However, without any sufficient cold air source, this looks to be isolated at best. Along the coastal plain rain should be the dominant precipitation type, although there may be a few sleet pellets at the onset given the large dewpoint depressions. It will be a cold raw rain, with temperatures hovering around the 40°F mark. The first batch of precipitation won’t be terribly heavy or steady, with about a quarter to a third of an inch expected. Where this falls as snow an inch or two, possibly three, will coat mainly the cold/grassy/snow covered surfaces. Surface ridge axis over northern New York and New England should keep these areas dry but clouds will thicken as the day progresses, limiting sunshine. Across the north highs will be within a few degrees of freezing.


The entire double(triple?)-barrel mess moves into the Northeast Sunday night into Monday. This is where it gets even more complicated. Neither low looks to take over, sharing energy equally amongst themselves and remaining broad. Convection off the coast associated with the coastal front interacting with the Gulf Stream may help to keep lower pressure just offshore, tending to pull the coastal east, even though the trough axis is displaced rather far to the west. Owning to this far west upper trough axis will be the primary low, moving towards the west end of Lake Erie. Since this system is so broad, with the low pressure centers of the double barrel complex being nearly 600 miles apart and very little baroclinic energy for it to feed off of, there won’t be any major intensification of either low, with both hovering in the mid-990mb range. The center of the 850/700mb low tracks will also be up the west side of the Appalachians and without any high pressure to lock in the cold air over the Northeast, mild air will overspread the region, changing much of the snow over to a mix or rain. The regions that do remain all snow will be confined to the Adirondacks and northern Green/White mountains in northern Vermont and New Hampshire and northwestern Maine. There may be a period of significant sleet and freezing rain across northeast Pennsylvania, the Catskills, Berkshires and Mohawk Valley region as 850mb temperatures rise to 2-3°C overnight but the boundary layer remains near freezing or slightly below. Elsewhere to the south, precipitation will be in the form of rain. There may be a slow rise in temperatures during the night, but ageostrophic flow across the icing threat areas should keep temps at critical level. Along the coastal plain temperatures should be in the 40’s with 20’s across the far north along the Canadian border.


The Slop





Mid-term - Issued 11/29 @1:45am


Milder air floods into New England on Monday as the snow to mix to rain scenario occurs across the interior. To the west, a cold front moves through New York and Pennsylvania, reaching western New England by evening. Behind this front and leftover rain will change over to snow as strong cold air advection blasts in. Southwesterly flow behind the front will bring lake effect to the Niagara Frontier and the St.Lawrence Valley. Temperatures will remains steady or slowly fall into the 30’s behind the front, with 40’s along the coast. Across New England, temperatures will rise into the 40’s, with 30’s confined to the far north.


Upper trough axis remains over the region on Tuesday. Winds will back to more of a westerly direction with lake bands dropping south and snow showers and/or flurries spreading over the interior as lapse rates increase during diurnal heating in a moist, cyclonic flow regime. Temperatures will fall below normal.


Long-term - Issued 11/29 @1:45am



Next system of concern moves in late Wednesday and early Thursday. A negatively tilting upper trough will approach with a strong cold front along its flanks. This front has anafront characteristics in the models thus far and should bring a rain to snow shower event for most and could drop a couple inches across the interior. Temperatures will climb above normal ahead of this front but drop sharply behind it, to 5-10 degrees below normal. Lake effect snow regime becomes established once again to close out the week with a continuation of much below normal temperatures into next weekend. We may also be dealing with another winter storm by next weekend, if current model trends hold.



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Radar: Northeast Region Loop



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Current snowcover




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Local SST's



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2008-09 Winter Forecast