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Significant winter weather event possible next week

Forecast models have come into much better agreement regarding a storm system which is forecast to impact the area early next week. Several days ago we mentioned in a blog post that the next significant precipitation event wouldn’t come until early this coming week — and that idea continues. A powerhouse upper level trough will slam into the West Coast over the next day or two, providing much needed rains. But more interestingly for us, the associated energy will de-amplify somewhat, but eject northeastward towards the Tennessee and Mississippi Valleys. As a result, a surface low pressure system will develop from the Arkaltex towards the Mid Atlantic coast.

To our north, a piece of the Polar Vortex will be meandering in Southeast Canada, maintaining an impressive low level cold air source. The result of the ejecting shortwave and cold air to the north will be an impressive thermal gradient and stalled frontal boundary, which will extend from the Central US towards the Mid Atlantic. Along this thermal gradient, a plume of moisture is forecast to develop in response to enhanced lift from the aforementioned disturbance. Accordingly, areas to the north of this thermal gradient (including much of our forecast area) will be in line for a potentially significant winter weather event.

GFS model showing a large-scale winter weather event impacting the Eastern United States early next week.

GFS model showing a large-scale winter weather event impacting the Eastern United States early next week.

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Wednesday’s light snow gives way to near record cold

Light snow is falling throughout the area this morning and will continue to do so for the next several hours. The culprit is a weak mid level disturbance and associated elongated surface low, which in actuality is quite progressive and weak. But sufficient lift for precipitation and the presence of markedly colder air will set the table for a very light snow event through Wednesday evening. Accumulations will be quite light, thanks to the transient and light nature of precipitation and still relatively warm ground temperatures, ranging from a trace to 1″ in some isolated areas. The snow is expected to wind down by later Wednesday afternoon.

More notable than the light snow accumulations will be the impending shots of cold air, which will move from Canada and the Great Lakes into the Northeast on Thursday and Friday. A piece of the displaced Polar Vortex will shift southeastward toward Southeast Canada, and the resulting arctic front will drag anomalously cold air into the area behind Wednesday’s weak storm system and another clipper on Thursday. Temperatures aloft, at the 850mb level to be specific, will fall below -20 C in much of the area. Compare that to the +15 c temperatures at 850mb which reached the area last Friday, and you have yourself an idea as to how cold the airmass really is.

High resolution NAM model forecasting low temperatures in the single digits to near zero in the area on Friday morning.

High resolution NAM model forecasting low temperatures in the single digits to near zero in the area on Friday morning.

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Ending the developing misconceptions regarding the Polar Vortex

It has been a media frenzy. Since January, when a piece of the Polar Vortex made its dramatic trip through the Central and Eastern United States, the misconceptions regarding its origins and actual definition have continued. Whether made in a joking manner or not, some of the ideas regarding the Polar Vortex’s actual characteristics have created a bit of an issue for meteorologists. When using it to describe the pattern, we now have to keep in mind the potential media impacts. To be frank: That is not the way it should be.

The Polar Vortex, in our hemisphere, is a persistent cyclone which is located near the North Pole. It features a counter-clockwise rotating pool of cold, dense air — some of the coldest on the globe, in fact. The vortex moves around to a certain extent, but generally remains in the vicinity of the poles. What separates and moves southward (sometimes towards our area) in anomalous patterns, are pieces of the Polar Vortex which feature characteristics of the vortex itself and similar air masses.

A significant piece of the Polar Vortex is forecast to drop into Southeast Canada later this week. Here, the GFS model forecasts its position at 500mb at 84 hours.

A significant piece of the Polar Vortex is forecast to drop into Southeast Canada later this week. Here, the GFS model forecasts its position at 500mb at 84 hours.

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Cold, with nuiscance-type snow events this week

So far this winter, nearly every potential winter weather event has turned into something much larger than originally anticipated. This has created headaches and long work nights for meteorologists and forecasters alike. This week, we look to buck the trend a bit. A parade of disturbances through the mid levels of the atmosphere look likely to bring opportunity for light snowfall, but the progressive nature of the pattern will ultimately keep these events fast, with no significant or heavy precipitation and generally weak low pressure centers.

The result will be multiple periods of light snow, first on Tuesday afternoon and evening especially across Southeast New Jersey. Additional periods of light snow are expected both Wednesday afternoon (area-wide) and Thursday (mostly across northern zones). But when all is said and done, the general theme will be light accumulations only (generally a trace to 1″), as the intensity and duration of the snow will be far too light to cause any significant issues. Still, roads could become slick for a period of time so as always we advise traveling with caution. There are no signals for banding or areas of heavy precipitation that could surprise us.

NAM model forecasting light snow/snow showers to impact the area on Wednesday (similar impacts expected Tuesday).

NAM model forecasting light snow/snow showers to impact the area on Wednesday (similar impacts expected Tuesday).

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