Thursday, January 6, 2011

Another chance of snow on the horizon

As promised earlier today, it's time to start looking more closely at the threat of snow in the extended forecast. Since we are still 3-5 days out from this potential event, I'll stay fairly high level. Future forecasts and discussions will refine the threat further.

The scenario for Sunday and early Monday is a fairly classic wintertime one for the Mid-South that typically brings either snow or nothing, but with the potential for some accumulation. In the wake of a weak cold front that will move through on Friday, cooler air will build into the region for the weekend. Meanwhile, low pressure will move east across Texas on Saturday and near the Gulf Coast on Sunday. On the north side of the low, the Mid-South will be positioned in a cold airmass with moisture circulating around the low from the Gulf. Behind the low will, extremely cold air will be ushered in by upper-level disturbances swinging through the area early next week. Thus, the time frame for potential snowfall in the Mid-South will be sometime during the day Sunday through at least Tuesday.

Typically, there are three ingredients that must come together to bring snow to the Memphis area in the scenario we see this weekend - sufficient cold air, sufficient moisture, and the track of the low pressure system. The first appears to not be a problem. I don't expect to spend too much time figuring out what type of precipitation will fall. Cold air will be in place with temperatures only in the 30s Sunday. The second, sufficient moisture, is a little more problematic and plays well into the third, which is the biggest question mark at this time. If the low tracks a little further north (say over land north of the Gulf coastline), we have a better chance of seeing snow and possibly some accumulation. If it tracks over the Gulf waters, it could be too far south to bring more than flurries or very light snow. The track of the low will be the main forecast concern for the next few days. The next forecast concern is the strength of any upper-level disturbances that move through Monday and Tuesday and the amount of moisture in place, which will determine the snow amounts Monday and Tuesday.

In any event, the potential exists for school-closing amounts of snow (which as you all know is only an inch or so...) from late Sunday through Monday, with light accumulations into Tuesday. The part of the forecast that I am most confident in is that VERY cold air will be in place a good part of next week. In fact, if there is snow cover, we could see highs only in the 20s! I'll keep you updated via this blog, the MWN Forecast, and Facebook and Twitter throughout.

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