Monday, March 23, 2009

Severe Weather Possible This Week....

Severe weather is possible throughout the week as numerous storm systems move across the Southern Plains. The first threat of severe weather will move into East Texas tomorrow as a strong storm system to our north drags a cold front across our area. As this cold front moves in, a line of strong to severe thunderstorms will breakout, starting around midday in our northwestern counties and exiting our southeastern counties by early Wednesday morning. The main severe weather threat with this system is strong gusty winds and hail, although an isolated weak tornado can't be ruled out.

Our second chance of severe weather will enter the area late Wednesday as the cold front, now stalled across the Gulf coast, begins to move north as a warm front. Ahead of this warm front, warm air will be forced over cooler air at the surfaced causing thunderstorms to form above the planetary boundary layer, air near the surface of the Earth affected by friction. There will be a lot of what we called elevated energy available for these storms to grow, so large hail is a possibility when any of the stronger storms Wednesday night into Thursday morning. Along and south of the warm front, thunderstorms will have the best chance for rotation so we will have to watch for the possibility of tornadoes if any stronger storms can form.

By Thursday afternoon the warm front should have moved north of East Texas putting all of our area in the warm sector of our next developing storm system. With ample daytime heating, enough energy will be present for isolated to scattered thunderstorms Thursday afternoon. With the available directional wind shear, or winds turn with height, a few of these storm late Thursday could be very strong with large hail, gusty winds, and even a couple of tornadoes. The image below shows 0-1KM EHI or energy helicity index. This value takes into consideration both the amount of energy available for a storm and the amount of spin in the atmosphere. Any number greater than 2 means tornadoes are possible and a number over 4 means strong tornadoes are possible. Right now the EHI over East Texas is forecast to be as high as 3.75.(Some meteorologist will say strong tornadoes are possible with a reading greater than 2 but, the majority of strong tornadoes are associated with a higher number)

By Friday afternoon a strong cold front will move through East Texas again but this time, we should clear out and cool off for the weekend. With this front scattered to numerous strong thunderstorms will develop bringing a chance of gusty winds, hail, and even isolated tornadoes. All of East Texas should remain on guard for the threat of severe weather and stay tuned to KLTV and for the latest.

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