Monday, February 16, 2009

Valentine's Night Storm........

For all those lovers of exciting weather Cupid shot his arrow into the atmosphere and whipped up some elevated thunderstorms Valentine’s Night bringing a vivid lightning show and small hail to parts of East Texas. The lightning shots you see here were taken from my front porch as a strong storm moved out of Eastern Henderson County into Smith County.

This storm produced a large amount of small hail, covering the ground and causing hazardous travel along 346 from Flint to Whitehouse. The largest hailstone I found was penny size which technically is severe near the intersection of 346 and Oakbrook. These storms fired with a combination of many atmospheric conditions which came together over East Texas.

First, in the mid levels of the atmosphere a weak disturbance was entering West Texas causing the winds to diverge over East Texas. This causes the air to rise which could lead to clouds and precipitation. Second, a strong jet stream in the upper level of the atmosphere was moving just to our south. This put East Texas in what we call the left exit region of the jet stream which also adds in lifting the air.

Third, strong wind shear was noted in the atmosphere from 6,000’ to 30,000’. This will help aid in thunderstorm development by pushing the rain cooled air downstream, away from the storms updraft allowing the storm to become stronger.

The only thing missing for thunderstorm development, moisture. The low levels of the atmosphere where we normally find the moisture needed for thunderstorm development were too dry for surface based storm development. However, in the lower mid levels of the atmosphere a thin layer of moisture was moving into East Texas. This was all that was needed to help fire what we call elevated thunderstorms. Since the low levels of the atmosphere were dry, we were giving a vivid lightning storm with great visibility, giving many photo opportunities.

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