Joe Lundberg

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Eastward Shift in Nor'Easter, Then Promise of Coast-to-Coast Changes

November 6, 2012; 10:43 AM ET

Tuesday, 11:30 a.m.

It's Election Day 2012, a day when we have the opportunity to get out and exercise our right to vote. I hope that whatever the weather may be in your area, and whatever your political persuasion may be, that'll you get out and cast your vote, if you have not already done so via mail-in ballots or early voting. It is a right that has been defended and fought for by many brave souls, many of whom gave their lives to protect our freedoms.

The weather through the time the polls close will be good in most of the country. There is a little rain and wet snow falling across Wisconsin and easternmost Iowa into northern Illinois at this hour from a weak upper-level disturbance. Some of the rain will leak into Indiana and western Kentucky later this afternoon and early tonight, as well as portions of Tennessee, but none of it will be heavy. And by then, what little snow that will have fallen in Wisconsin will have ceased. There can also be a little rain in northwestern Washington. Aside from that, and, of course, the developing nor'easter, most of the country will have some pretty quiet weather.

Then there is, of course, the developing nor'easter. A couple of things can be pointed out that are of interest. One is the fact that it has already begun to clear in northern Florida, a sign that the low pressure area is already escaping out to the northeast side of the state. There can still be some instability showers around this afternoon, but the steadier rains are done. This is all a little faster than would have been suggested by the modeling yesterday.

Another important thing to note is that over the interior mid-Atlantic now, there's really not a strong surface high to overrun. High pressure over New England is in place, and that's where the best overrunning will be noticed tomorrow into Thursday. That may spare the mid-Atlantic region of most of the snow that will be tied to the storm when all is said and done.

And, lastly, is the simple fact that most of the computer guidance shifted the track of the storm farther east since this time yesterday. Does that mean the mid-Atlantic and New England are going to avoid the storm? Hardly. What it is likely to mean is areas from west of the Chesapeake up through the Susquehanna Valley will have limited effects from the storm, mainly clouds, but not much precipitation.

One of the more challenging aspects of the storm will be the rain vs. snow question from, say, northeastern Maryland and eastern Pennsylvania up into New England. If you look at it from a climatology standpoint, it is very, very hard to get it to snow along and especially east of the I-95 corridor this early in the season. The boundary layer temperatures are just flat out too warm. Water temperatures off the mid-Atlantic coast are in the mid- to upper 50s, so if there's any ocean component of the wind, that will raise the surface temperatures enough to make it really, really hard to get it to snow and even harder to get it to stick. I'm not saying it cannot happen, just that there's a lot to overcome to make it happen.

Farther inland, it is more plausible, especially with any increase in elevation. So that means areas from northwest of Philadelphia up into the Poconos and the northwest hills of New Jersey, then across the high terrain of the lower Hudson Valley into the northwest hills of Connecticut are at least in the discussion.

It should also be noted that the models have differing opinions as to how cold the lower part of the atmosphere will be tomorrow afternoon and tomorrow night into Thursday. If it is going to happen, the best chance of it happening is tomorrow night and early Thursday. After that, the storm will be weakening and drifting off to the east and northeast, and the cold will be fading.

What should not be lost in the discussion is the wind impact on the region. There can still be winds gusting to 50 and 60 mph up and down the mid-Atlantic coast and across most of Long Island. Across coastal southern New England, it won't be as windy. This will be enough to cause some scattered power outages in areas that have been able to regain power after Sandy.

The expected 2- to maybe 3-foot storm surge will also cause some coastal flooding tomorrow and tomorrow night, specifically along the coast of New Jersey. Without the protection of the dunes, that makes more areas susceptible to flooding.

Beyond the storm, things change dramatically. The record heat in the West is about to get erased by a deepening upper-level trough coming out of the Gulf of Alaska. Look at the latest NAM forecast for Friday evening:

Gone is the ridge; wiped out is the warmth. That's a very deep upper-level trough that will generate snow in the mountains throughout the West. And as the the trough migrates into the West, it will cause the trough in the East to lift out, to be replaced by upper-level ridging. Look at the Sunday evening GFS 500mb forecast:

And look at the contrast that is set up across the country Friday as a result of this change:

As low pressure charges out of the Rockies and into Nebraska and South Dakota Saturday, the contrasts will be even more striking:

As high pressure moves away from the East, some of that warmth in the Plains and Mississippi Valley will come not only into the Ohio and Tennessee valleys, but also the East. After a lengthy period with temperatures below normal in the eastern half of the country, especially from around the Great Lakes to the mid-Atlantic states, that will be a welcome change!

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com

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Joe Lundberg
Joe Lundberg, a veteran AccuWeather.com forecaster and meteorologist, covers both short and long-term U.S. weather on this blog.