Saturday, March 5, 2011

Here is a rough timeline for today's rain. The shades of green indicate light to moderate showers, while yellows and reds indicate downpours or possibly thunderstorms. There is a very slim chance for severe storms in central and southeast Virginia today.

Rain totals should range from around 0.75" to 1.25" (give or take 0.25"). This is great news considering that we are about 2.5" below normal for the year.

Severe Weather Checklist
  1. Instability (heat and humidity)
    Moisture should be high enough to support thunderstorms. Temperatures will be hindered by clouds and rain, especially along and west of I-95. Highs should climb into the mid 60s for central and southeast VA. This should be *just* warm enough for isolated thunderstorms.

  2. Trigger (something to spark thunderstorm development)
    A strong front will pass the area in the afternoon, which is typically ideal for severe storms.
  3. Wind Shear
    We will have strong speed shear (winds increase with height), and minor directional shear (winds change direction with height).
  4. Sunshine
    Clouds will prevent any sun for today, which in turn keeps us cooler.

This looks like yet another event where wind shear will be very high but instability will be low. If temperatures climbed into the mid 70s, we would have a bona fide severe weather threat. Regardless, we still have to watch this very closely today. If a thunderstorm develops, it could quickly become severe.

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