Thursday/Friday Storm System
The models made a pretty impressive shift last night to a more wintry solution for the system I have been keeping my eye on for over a week now. Now when I say this, I want to caution everyone that this is not your classic setup for a southeast snowstorm. For those of you remember, I did and have done a good deal of research in the past on the synoptic weather setup signals for major southeast winter/snow storms http://raleighwx.americanwx.com/research.html . Many of those signals are not present in this setup, but it does look like there could be enough positive factors for some wintry weather to occur.
The culprit is a closed upper low that will form today across the southern Plains of the US and then shift east through the next 48 hours. While this cut off low is not particularly strong, it will apparently maintain a separate identity from the northern stream and at the same time be aided by the northern stream. This will combine to produce a strengthening low pressure off the SC coast by later tomorrow. As the storm starts to strengthen some tomorrow, it will be raining across most areas of Ga, SC, NC, Va, but the western and northwestern fringes of the storm across Al/TN,NW Ga/eastern KY, western Va, and the southern Appalachians will start to change over to snow. This area of snow will be associated with a vigorous deformation band that will setup as the storm strengthens. The surface low will move ENE and we should see the amount of coverage of snow increase as night falls and the strong lifting continues. The changeover to snow will progress eastward across NC, the upstate of SC, Va, and the lower Delmarva. This will likely provide many with a 3-6 hour period of snow. I have posted some model graphics in the slideshow to peruse as well.
It is difficult to place much faith in model snowfall forecasts, as they are typically overdone. However with this anticipated scenario I have produced my first forecast for this event. I admit that individual forecasters in their own local climate areas are likely to do better, particularly in the mountains and in east TN which is always a bear for me. But this is how I think it unfolds. Again for many outside the mountains this will be a short event, so snow totals will be kept down. Where it snows hard the warm ground temperatures will not be a problem, however where snow rates are light the warm ground will likely prevent any accumulation. Also it appears during the height of the storm temps will be around 32-34 for many of us, so it could be hard to see accumulation on roads unless the snow is coming down hard.
I will monitor the data throughout the day and post an updated post/forecast either this afternoon or evening. Also follow me on twitter @RaleighWx and on http://americanwx.com/bb where I post as RaleighWx for updates during the day.