Evening Weather Update

What a severe weather outbreak to begin the 2010 severe weather season. Multiple reports of tornado damage across the eastern third of Texas.

*Baseball sized hail falling now in Gilmer, Texas in Upshur County. Serious tornado signature on radar. Very dangerous storm.
*Major damage reported near Sulphur Springs, Texas
*People reported trapped in homes and businesses near Waskom, Texas, in Harrison County near the Louisiana line.
*Major damage near Canton, Texas, which is about 60 miles east of Dallas in Van Zandt County.
*A storm producing a tornado is moving up into southern Smith County, Texas, moving in the general direction of Tyler.

Some of you know I used to work for KDFW-TV, Channel 4 in Dallas in the 80s, so this is very familiar territory for me.

In Mississippi, the storm north of Jackson showed strong signs of producing a tornado about 30 minutes ago; rotation has weakened and the tornado warning was cancelled.

Here is a look at the current instability across the region:

As you can see, all of the surface based instability remains to the west of Alabama, where the severe weather is in progress. We will see an increasing low level jet late tonight across Alabama, but instability values will remain marginal.

The bottom line is that we mainly expect a heavy rain event in Alabama late tonight into early tomorrow morning, with potential for 1 to 2 inches of rain. Severe storms can’t be ruled out, but a major event is not expected. The best chance of a severe storm late tonight will be west of a line from Muscle Shoals to Birmingham to Montgomery to Geneva.

But, when it comes to thunderstorms, expect the unexpected, so we will be watching the radar trends carefully tonight. The biggest problems should remain to the west. Here is a late mesoscale discussion from SPC:

MESOSCALE DISCUSSION 0027
NWS STORM PREDICTION CENTER NORMAN OK
0642 PM CST WED JAN 20 2010

AREAS AFFECTED…NORTHEAST TX/NORTHERN LA AND FAR SOUTHEAST OK/FAR
SOUTHERN AR TO CENTRAL/SOUTHERN MS

CONCERNING…TORNADO WATCH 1…2…

VALID 210042Z – 210215Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 1…2…CONTINUES.

AN APPRECIABLE TORNADO POTENTIAL IS LIKELY TO CONTINUE THROUGH THE
EARLY/MID EVENING HOURS ESPECIALLY ACROSS FAR NORTHEAST TX/NORTHERN
LA AND FAR SOUTHERN AR. FORTHCOMING 01Z CONVECTIVE OUTLOOK WILL
INCLUDE SLIGHTLY UPGRADED SEVERE PROBABILITIES…AND A NIGHTTIME
PUBLIC SEVERE WEATHER OUTLOOK /PWO/ WILL BE ISSUED WITHIN THE HOUR.

A NUMBER OF SUPERCELLS /SOME POTENTIALLY TORNADIC/ ARE LIKELY TO
CONTINUE OVER THE NEXT SEVERAL HOURS ESPECIALLY ACROSS FAR NORTHEAST
TX/NORTHERN LA…AND PERHAPS INTO FAR SOUTHEAST OK/FAR SOUTHERN AR.
AS THE UPSTREAM SHORTWAVE TROUGH/SPEED MAXIMA CONTINUES TO CROSS
TX/OK…INCREASING SURFACE CYCLOGENESIS IS MAINTAINING CORRIDOR OF
PRESSURE FALLS/BACKED SOUTHEASTERLY LOW LEVEL FLOW ACROSS FAR
NORTHEAST TX/NORTHERN LA IN VICINITY OF A WNW-ESE ORIENTED WEAK WARM
FRONT. WITH LOW LEVEL FLOW/SRH EXPECTED TO ONLY INCREASE THROUGH MID
EVENING…SCATTERED SUPERCELLS WITH TORNADO/HAIL POTENTIAL WILL
CONTINUE.

..GUYER.. 01/21/2010

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