Will Another Winter Storm Hammer the East This Week?

By: By Jon Erdman

Published: February 23,2014

 

 

 

 

In just over a month's time, The Weather Channel has named ten winter storms, which averages out to one every three to four days.
The Northeast has been impacted by seven of these, while five storms have impacted — and in some cases, crippled — parts of the South.
(MORE: Science Behind Naming Winter Storms | 10 Cities With a Top Five Snowiest Winter)
The week ahead will bring another threat of a winter storm, as fresh cold air is poised to pump into the nation's Midwest, South and East, which will be coupled with an active jet stream. Let's break down what we know, and still do not know, at this time.

Tuesday's Forecast Map

Any South Snow, Ice?

• Threat: Light sleet, freezing rain, or snow on the northern fringe of the precipitation shield from parts of Oklahoma into the Tennessee Valley and southern Appalachians
• Timing: Tuesday, Tuesday night and early Wednesday
• Uncertainties: How fast the cold air will arrive. If it arrives faster, precipitation may change to freezing rain, sleet, or snow sooner, with more accumulation possible. For now, any amounts appear to be very light and very spotty.

Wednesday's Forecast Map

East Coast Storm?

• Threat: Snow, possibly heavy for some, from the Appalachians and Virginia northeastward along the I-95 corridor to New England
• Timing: Wednesday into Wednesday night
• City forecasts: Washington | Philly | NYC | Hartford | Boston

Let's dive into more detail about the uncertainty regarding the East Coast system.

European Model Wednesday

GFS Model Wednesday

Where Will the Low Track?

Unfortunately, it's typical for there to be a large degree of uncertainty about a potential winter storm that's four to five days away.
With winter storms, the track of the surface (i.e., near ground-level) low pressure center is key to determining where the heaviest snow falls, as well as the demarcation lines between rain, sleet/ice and snow.
Meteorologists track disturbances in the upper levels of the atmosphere. This is because these disturbances spin up surface low pressure systems and sharpen up attendant cold and warm fronts you're familiar with.
In the case of this week's potential storm, the surface low hasn't even formed yet. The upper-level disturbance that is expected to spawn this area of surface low pressure is more than 3,000 miles away over the Beaufort Sea, located north of Canada's Yukon and Northwest Territories.
Subtle differences in how forecast models handle this disturbance's strength can make a huge difference in the forecast of a potential storm that is days away.
The Wednesday afternoon forecast images above at right, taken from Sunday morning's forecast models, show the model-simulated surface low positions at noon (translucent "L") and 6 p.m. Wednesday (opapue "L") to give you an idea of the models' projected paths. As you can see, the models are keying in on a surface low track that's close enough to the coast to bring some snow, but not close enough for a major storm.
That said, previous recent runs of these same models have produced a wider range of results:

• A moderate, possibly heavy snowstorm (surface low stronger, closer to the coast)
• Little to no significant snow (surface low farther out to sea, weaker) 

Frustrating, right? This is why we cannot yet break down any of the forecast details you would understandably like to know, such how much snow we'll see.
Given the fact that none of the major computer forecast models Sunday morning show a major Northeast coastal storm, our official forecast paints "snow showers" across the Northeast, implying modest amounts.
However, few low pressure systems this winter have swept out to sea without spinning up close to the coast, which wrung out at least some snow over the East.
Also, there are quite a few more runs of the computer models before Wednesday. Just because the models seem to be honing in on a scenario 3 1/2 days ahead of time does not mean that the forecast cannot change.
As you may recall, Winter Storm Janus began as a lowly Alberta clipper, and it only became apparent that it would produce heavy Northeast snowfall about 48 hours in advance. Up to 18 inches ended up falling in Massachusetts.
Check back with us at weather.com and The Weather Channel as we refine this forecast in the days ahead.

MORE: Winter Storm Pax Photos (Feb. 10-14)

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Parker Evans, front, and Emmaline Hurst ride their sled down a hill after being pushed by Mike Evans Thursday, Feb. 13, 2014, in Knoxville, Tenn. after a winter storm Wednesday night dumped 5 to 9 inches of snow with more in surrounding areas. (AP Photo/Wade Payne)