11/14/2012

No Sandy, but storm likely that could snarl holiday travel

By Nick Wiltgen, weather.com

After several days' respite, we will again be watching the waters just off the Atlantic Seaboard for the potential of another coastal storm.

As has been the case with the last several storms near the East Coast, the computer forecast models have been showing a range of possible outcomes for this system, which will develop this weekend and reach its peak intensity during the first half of next week -- just as millions of Americans hit the road or the airport for Thanksgiving.

What can we say with confidence at this point?  We can confidently predict that a storm will be spinning up off the Atlantic shores of the Southeast this weekend.


Breezy conditions are likely at the coast, and showers will be possible from coastal Georgia into parts of the Carolinas and Virginia this weekend.

(FORECAST: Savannah | Charleston, S.C. | Raleigh)

Questions arise next week about where this storm is headed during the busy Thanksgiving travel period. Computer forecast models are in broad agreement that it will crawl northward over the western Atlantic, blocked -- or at least slowed -- by a strong bubble of high pressure over eastern Canada.

The models are also in good agreement that this storm will not pull a Sandy and make a left hook into the East Coast; in fact, they broadly agree on keeping the center of the storm over the ocean, but they vary quite a bit in how far offshore.

The models also agree that there won't be much cold air feeding into this system. This means the chance for snow (as opposed to rain) from this storm is quite low.

(MORE: Thanksgiving Travel Forecast | Forecast: Gridlock)

Given what we know, we expect a long fetch of easterly winds over the western Atlantic. But as we will see, those model differences will have implications for the coastal impacts of this storm.

So that's the critical question: Will this storm hug the coast or stay farther out to sea? 

Let's take a look at two of the possibilities for this low-pressure system.

On one hand, the center of low pressure could stay on a more westerly track as it moves north, keeping it closer to the East Coast.

In this scenario, rain would lash parts of the Mid-Atlantic and the Northeast into those heavy pre-Thanksgiving travel days, causing wet roads, traffic delays, and complications at the airports. There's likely to be more of an onshore (easterly) component to the winds along the East Coast, increasing the threat of some coastal flooding, not to mention severe beach erosion from pounding waves.  Furthermore, the winds would be stronger for a longer stretch of coast in this scenario.

(FORECAST: Boston | New York | Philadelphia | Washington, D.C.)

On the other hand, there's a possibility that this low pressure will take a track farther offshore.

In this scenario, most of the heavy rainfall would stay just offshore, greatly reducing the impact to holiday travel. There would still be blustery conditions along the immediate coastline, and certain areas could still be prone to some coastal flooding and high surf due to that long fetch of easterly or northeasterly winds.

But if this storm stays far enough offshore, we might end up with northerly winds instead of easterly winds along much of the Mid-Atlantic coast. Since those winds would be blowing either offshore or parallel to shore for most of the region, the coastal flooding danger would be greatly reduced.

One place that has to be vigilant in either scenario is Norfolk, Va., and the surrounding Hampton Roads region.  This region is notorious for coastal flooding problems on northerly winds given the orientation of the coastline at the mouth of Chesapeake Bay.

Again, in either scenario, we're looking at maximum impacts from Monday through Wednesday of next week.

Stay with weather.com and The Weather Channel. As always, we'll keep refining the forecast as the event draws nearer and the forecast picture becomes clearer.

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