MESOSCALE DISCUSSION 0238

MESOSCALE DISCUSSION 0238
NWS STORM PREDICTION CENTER NORMAN OK
0732 PM CST THU MAR 08 2012

AREAS AFFECTED...PORTIONS OF THE LWR RIO GRANDE VALLEY/SRN TX

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 090132Z - 090300Z

THUNDERSTORMS ARE EXPECTED TO DEVELOP AND INCREASE IN COVERAGE
TONIGHT OVER PORTIONS OF THE LWR RIO GRANDE VALLEY/SRN TX. THOUGH
STORMS MAY POSE A THREAT FOR LARGE HAIL AND DAMAGING WIND GUSTS...IT
DOES NOT APPEAR THAT A WW WILL BE NECESSARY ATTM.
HOWEVER...CONVECTIVE TRENDS WILL CONTINUE TO BE MONITORED.

SURFACE OBSERVATIONS SHOW A COLD FRONT ADVANCING SWD INTO SRN TX AT
01Z. WARM SECTOR AIRMASS AHEAD OF THE FRONT IS CHARACTERIZED BY
TEMPERATURES IN THE 70S TO NEAR 80 WITH DEWPOINTS IN THE MID TO UPR
60S. BEHIND THE FRONT...A SHARP INVERSION EXISTS ABOVE THE SURFACE
PER 00Z DRT RAOB...THOUGH A SUFFICIENTLY WARM/MOIST LAYER CENTERED
NEAR 850 MB IS AIDING IN MUCAPE VALUES CLOSE TO 1000 J/KG.
COMBINATION OF LARGE-SCALE ASCENT AHEAD OF A SWRN CONUS CLOSED LOW
AND INCREASING CONVERGENCE INVOF THE COLD FRONT APPEARS TO BE AIDING
IN THUNDERSTORM DEVELOPMENT BASED ON RECENT REGIONAL RADAR IMAGERY.
THIS ACTIVITY IS EXPECTED TO STRENGTHEN AND EXPAND IN COVERAGE
DURING THE NIGHT OVER THE REGION AS THE FRONT CONTINUES TO SURGE S
AND EWD. STEEP MIDLEVEL LAPSE RATES NEAR 8 C/KM...MUCAPE VALUES FROM
1000-2000 J/KG...AND EFFECTIVE BULK SHEAR VALUES RANGING FROM 40 KT
OVER THE WARM SECTOR TO 50-70 KT BEHIND THE FRONT WILL FAVOR
SUPERCELLS POSING A THREAT FOR LARGE HAIL. IN ADDITION...STORMS
FORMING CLOSE TO THE LEADING EDGE OF THE SWD MOVING FRONT MAY POSE A
THREAT FOR DAMAGING WIND GUSTS...THOUGH BOUNDARY LAYER COOLING
DURING THE NIGHT MAY DECREASE THE WIND THREAT WITH TIME.

..GARNER.. 03/09/2012


ATTN...WFO...HGX...CRP...EWX...

LAT...LON 29559554 27609783 27369892 27729976 28430024 29490010
30229861 30439647 29559554