Frozen Tundra Formerly Called the Northeast Braces for Weekend Snowstorm

Models are showing yet another multi-day winter storm in the Northeast this weekend. Accumulations could reach double-digits by Monday night, and that might not even be the worst thing to happen next week. We could see "Dennis Quaid hiking up I-95 to save Jake Gyllenhaal" levels of cold around Valentine's Day. Isn't winter fun?

The Setup

Models are in relatively good agreement today that a weak low pressure system will scoot across the Ohio Valley this weekend, producing rain and ice in the storm's warm sector, with all snow in the cold air to the north of the low. Snow should begin to build into the Northeast on Sunday afternoon and evening.

The system will move across the mountains on Sunday night and weaken, giving way to a developing coastal storm on Monday; this setup is known as a Miller Type B Nor'easter, if you were wondering. Snow will continue during the transition into a nor'easter, building with intensity before tapering off from south to north on Monday night and Tuesday.

Timing

The storm should start on Sunday night for most people, lasting through Tuesday morning as you look towards NYC and Boston, but we're still a couple of days away from the event. Small shifts could delay (or speed up) the start of the precipitation by twelve hours. Snow on Monday is a good bet, though.

Snowfall Totals

Here are some possible doom totals snagged directly from the snowfall accumulations spit out by this morning's GFS and European models—which are often overdone—valid through Tuesday night around sunset.

Snowfall totals are highly dependent on factors like atmospheric and surface temperatures (especially if sleet/rain mixes in with the snow), and dry air, which can cause snow to evaporate for a number of hours until the air moistens enough to allow it to reach the ground. The GFS model is pretty iffy on whether or not cities near and south of the low (like New York and Philly) will see all snow during the event. Any rain or ice will hold accumulations down.

And as we saw during last week's major blizzard, heavy snow bands can have a sharp gradient between blockbuster snow totals and much more meager amounts.

Polar-Vortex-Influenced Cold Snap Looming

If you thought we were done with the polar vortex panic, boy are you in for a treat! Models are strongly hinting at the threat of a "lobe" of the polar vortex slithering down across southern Canada and the eastern United States late next week.

The polar vortex, you'll remember, is a persistent upper-level cyclone that swirls in and around the Arctic Circle, sort of acting like a moat that keeps cold air locked into place where it belongs. When this circulation becomes wavy, a trough (or even a cut-off low) can move away from the main circulation and head south into lower latitudes. These troughs and cut-off lows can bring with them very cold Arctic air, which is what we saw happen last year on an extreme scale. It happens several times a year, but last year's brutal cold snap was the public's first introduction to the polar vortex, and just like a toddler learning a new word, they ran with it.

If you look at the above model forecast image from this morning's run of the GFS model (valid around sunset on Thursday the 12th), which shows heights at the 500 millibar level, you can see the main circulation in the polar vortex planted firmly along the western coast of Greenland, where it normally likes to hang out. A trough extending from this parent circulation will swing down over the eastern part of North America, which could (and probably will) bring with it brutally cold temperatures for a day or two.

If the predicted pattern holds, we could see widespread subzero low temperatures towards the end of next week (lasting through the weekend) from the Upper Midwest through the Northeast—and we're not talking a few degrees below zero, either.

We'll deal with this as we get closer to the event, but suffice it to say, winter isn't done with us yet.

Seasonal Snowfall Totals

The last couple of storms have really padded seasonal snowfall amounts in the Northeast. Here's a look at how much snow some major cities have seen so far this winter (December 1 through February 4). The above map shows snowfall depths as of February 5.

Washington (Dulles) — 8.7"
Washington (National) — 3.6"
Baltimore (BWI) — 6.5"
NYC (LaGuardia) — 27.5"
NYC (Kennedy) — 21.9"
NYC (Central Park) — 19.9"
Islip (MacArthur) — 35.7"
Albany — 40.0"
Hartford — 28.6"
Boston (Logan) — 50.8"
Portland (Jetport) — 55.6"
Bangor — 66.5"

There are 43 days left until astronomical spring (and 24 days until meteorological spring). I think at this point we would all welcome the debilitating allergies and occasional mile-wide tornado if it means we get a month or two of open-window weather.

[Images: AP, Tropical Tidbits]

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