Monday, March 30, 2009

Gusty Winds and Small Hail Possible Early Tuesday:

After the threat of severe weather much of last week, strong storms could move into our area once again. A strong area of low pressure will be moving across the Northern Plains causing blizzard conditions for the Dakotas. It is this storm system that will drag a cold front down across East Texas early tomorrow morning bringing the threat of thunderstorms. At this time we are not expecting wide spread severe weather however we could see a few reports of hail up to the size of pennies and winds guts to 50 mph as this line moves through. The latest data is pointing to a small threat that a few of these storms could become severe, so we will be monitoring the line very closely as it moves through East Texas tomorrow morning. So what’s the set up for tomorrows morning’s storms?

In the image above, surface wind direction and moisture are indicated by the blue streamlines and green shading. This image is showing south southeasterly winds across East Texas and dewpoint temperatures, or the amount of moisture, in the low 60s. The next image shows the dewpoint temperatures along with the Surfaced Based Lifted Indices, or the difference in temperature of the environmental air and the lifted air from the surface. When ever the LIs are negative, instability is present, which could lead to the development of thunderstorms. The lower the LIs, the greater the instability. As the image shows, LIs are approaching -4 across the southern sections of East Texas.

In the next image below we can see that the air temperature will be in the mid 60s, outlined in the light orange color. This along with dewpoints in the low 60s will produce a low cloud base or LCL, lifted condensation levels. We look for low LCL to aid in the development of tornadoes.

Finally in the next two images we see the amount of CAPE, convective available potential energy, or buoyancy from air lifted at the surface and from air lifted at its most buoyant point. Both of these images show moderate amounts of CAPE, especially the MUCAPE, air lifted from its most buoyant point. The MUCAPE at the time of thunderstorm initiation is forecast to be over 1500 J/kg, more than sufficient for the development of hail. So why are we not anticipating a large outbreak of severe weather?

With the area of low pressure well to our north, the forcing needed to lift the air to create storms is lacking. We do see and area of added lift with a fast jet streak moving into our area but widespread severe weather is not anticipated. We will be monitoring this developing situation in case any storm gets out of hand tomorrow so stay tuned for the latest.

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