Joe Lundberg

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After the Bitter Blast, Back-and-Forth Pattern for Early April

March 25, 2014; 10:45 AM ET

Tuesday, 11:55 A.M.

Snow is falling this morning in portions of northern and western North Carolina and Tennessee, and the snow is sticking on the ground quite well in portions of Virginia. Thankfully, it is falling during the daytime, and it is late March, so even though the snow fall rates in some areas are an inch per hour or more, most roads are just wet when examining web cams at most lower elevation locations around Virginia.

Much of this snow is much more associated with the upper-level trough coming in from the Great Lakes and Ohio Valley than it is the surface storm moving away from the Southeast coast. By the time we get to early tonight, the trough will be merging with the surface storm to cause it to deep explosively, resulting in a massive and powerful storm that will pass pretty far southeast of Cape Cod tomorrow morning. By the time we get to early tonight, most of the snow tied more to the upper-level trough will be ending, while the snow tied to the offshore storm will take over. That said, it will largely be restricted to the Chesapeake Bay/Delmarva peninsula areas, with the snow the cutting across southeastern New England late tonight and tomorrow morning. Maine will bear the brunt of the storm tomorrow, and these latter two areas will get the most snow and the strongest winds when push comes to shove. Here's the 12z March 25 NAM projected QPF totals through Thursday morning:

Putting all of this together, and there is a concern in portions of southern Delaware to the Virginia Tidewater areas for more than 6 inches of snow, with some of that actually sticking to the road for a time early tonight before it comes to an end. Parts of Cape Cod will get hammered by the storm, with gale-force winds whipping the snow into deep drifts. Eastern Maine, Nova Scotia, and New Brunswick will really get crushed, with a likelihood of 1 to 2 feet of snow and extensive blowing and drifting snow.

The arctic air pouring across the Plains and Midwest behind all this today will sweep through the Southeast tonight and tomorrow, and will keep it much colder than normal through Thursday morning before there can be any hint of moderation. But moderation will come. And it will come quickly.

By Thursday evening, the next storm, rather than moving around the southern periphery of the cold, will attack it with a vengeance, heading from the eastern Rockies and western Plains tomorrow evening toward the northern Lakes early tomorrow night. Look at the 12z NAM surface forecast for 00z Friday:

South to southwest winds will bring much milder air up through the Plains tomorrow, and across the Mississippi Valley into the Tennessee and Ohio valleys tomorrow night and Thursday. It will also become much more moist, resulting in a rapid expansion in cloud cover, and producing some rain. As the storm goes by, it will pull a piece of arctic air southward from the Canadian Prairies. However, this chilly air mass won't get very far south, as the upper flow downstream, instead of being northwesterly, will be much more zonal, if not a little west-southwesterly. And that means the advance of cold will be halted on Friday. In turn, that means the front coming through the Northeast and Ohio Valley going into Friday will stall from the mid-Atlantic states back into the Ohio Valley, allowing another wave of low pressure to form along the front. And that means more rain seems likely in the Ohio and Tennessee valleys Friday into Friday night, spreading across the Appalachians into the mid-Atlantic and New England Saturday. Here's the 0z GFS forecast for Saturday afternoon:

Once this wave passes, drier and chillier air will follow from the Midwest and Mississippi Valley into the Lakes and Ohio Valley later Saturday and Saturday night, and into the East Sunday.

When you step back and look at the pattern as a whole from the Plains to the East Coast after Thursday, the pattern doesn't look anywhere near as cold as it had been, but the back-and-forth nature of things in early April will be biased cold, especially north of I-70, while it's biased warm to the south.

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.