Friday, March 25, 2011

Wintry Mix This Weekend?

Over the past couple days, computer data has been hinting at the possibility of wintry weather this weekend. I just got done looking at the latest data this evening, and it continues to show this scenario.

A few rain showers could clip the area during the day Saturday, especially in southern VA. Precip will intensify Saturday night into early Sunday as an upper-level storm system approaches. During this time, central VA could see a mix of sleet (ice pellets) and rain. Northern VA could see a mix of wet snow and rain.

A lot can change from now until Sunday, so we will continue to track this system and bring you more updates over the next couple days.

Legend for the maps below: Rain (green/yellow), Mix (pink), Snow (blue).

Technical Discussion

The key to the forecast in central VA will be the mid-level temperatures. I've posted a Skew-T diagram below. This shows temperatures and humidity from the ground (bottom of the diagram) all the way up 50,000 feet (top of the diagram). I've marked the freezing line in red. You can see the temperature line (pink line) is very close to freezing at 6000 feet, then much below freezing at around 4000 feet. This is your typical sleet profile (snow melts at 6000 feet then refreezes at 4000 feet). This will be something to watch when the new data comes out tomorrow.

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