Robert's post....

Blog 3/11/2010



Well if you like cloudy weather and off and on showers then the next few days are for you. Expect showers to arrive late morning today through this evening. Today will most likely be our heaviest rain day unless we get a heavy thunderstorm Friday. Showers through Sunday will be few and passing with light amounts. Temperatures should stay above normal through the weekend with temperatures in the mid 60s staying well above freezing at night.

There is a small chance for thunderstorms today and tomorrow but storms if any shouldn’t reach severe criteria. We will have the shearing of the winds to support severe weather but CAPE levels are far too low and will suppress development from occurring.

Yesterday appeared to be our first highly active severe day of the season. From the Southern Plains to the Gulf region, multiple tornado watches and severe watches were posted from the afternoon until the late evening. There were reports (see map) of Hail, wind, and tornadoes with even some injuries.

The reason why the spring is so active for severe weather is because of the winter fighting the summer for domination of Continental air mass. Between these two air-masses we have the Jet stream which separates the two. Along with the fronts, boundaries, lows, and deep Gulf moisture we have high CAPE values and high shear levels. CAPE is the convective available potential energy that allows air to rise during storm events. The higher the cape the more air that is available to rise and create thunderstorms. The Cape is high because the surface is warming rapidly during the day and the upper levels remain very cold because of the jet above. Since hot air rises, it rises even faster when there is cold air above. As for the shear, the shear organizes the storm and allows for them to become severe dropping large hail, winds, or even tornados. Since the Jet is so far south still the strong winds above spin and strengthen with height, organizing the storms. Once we hit the summer the Jet scoots back up to Canada and we see our severe chances drop for the South.

Robert Elvington