Wednesday, February 10, 2010

Snow Looking More Likely.

I must admit this winter weather scenario for Thursday and Thursday night has been one if not the most challenging forecast I have had to deal with. Right now it looks as though snow will fall across most of East Texas tomorrow and could accumulated in some areas, maybe as much as two inches along the I-20 corridor east of Tyler. But it could be worse.

Our official forecast for snowfall accumulations as of 9:00AM Wednesday is for around an inch of snow to accumulate on grassy surfaces along a line from Athens to Bullard to Carthage and points north. Along the I-20 corridor East of Tyler there could be as much as 2 inches. But as I write this new forecast data is coming into the office trending a bigger snow event, like was advertised on Monday.

What makes this forecast so difficult is the fact the temperature I the atmosphere straddles the freezing line from the surface to about 7000 feet. Usually we see in a situation like this, a warm nose of air around 5000 feet that melts the snow on the way to the surface. With this system we do not see that however, there are places where the temperature around 5000 feet does go above freezing. In these areas snow would melt and only rain would reach the ground. The problem is locating where this will occur and even if it does, heavy precipitation could cool this warm nose of air back to the freezing point and then we are back to snow.

Now if this warm nose of air never makes it up to the I-20 corridor, which some forecast models are showing now, nothing but snow will fall from Athens to Carthage north and this would cause a large increase in snow accumulation. In fact, looking at the latest snowfall accumulation chart, a swath of 4 to 5 inches in being shown across the I-20 corridor. I look for winter storm watches to be issued later today for parts of East Texas after looking at the latest data. Again, a lot could happen between now and the event but it is looking more like snow will occur.

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