

000 

WWUS20 KWNS 031812

SEL1

SPC WW 031812

LAZ000-MSZ000-TXZ000-CWZ000-040100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 801

NWS STORM PREDICTION CENTER NORMAN OK

110 PM CDT SUN AUG 3 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHERN AND WESTERN LOUISIANA

       CENTRAL AND SOUTHWEST MISSISSIPPI

       EAST CENTRAL AND SOUTHEAST TEXAS

       COASTAL WATERS



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 110 PM UNTIL 800

PM CDT.



HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 95

STATUTE MILES EAST AND WEST OF A LINE FROM 50 MILES NORTH

NORTHWEST OF JACKSON MISSISSIPPI TO 10 MILES SOUTH SOUTHWEST OF

HOUSTON TEXAS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).



REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE

FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH

AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR

THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS

AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY

DO PRODUCE TORNADOES.



DISCUSSION...THUNDERSTORMS HAVE DEVELOPED FROM CENTRAL MS SWWD INTO

EAST CENTRAL TX WITHIN LOW LEVEL CONVERGENCE ZONE...LEFT EXIT REGION

OF UPPER LEVEL JET...AND JUST NORTH OF AN MCV MOVING WWD ALONG THE

EXTREME SERN TX COAST.  SOUNDINGS AND WATER VAPOR IMAGERY INDICATE

DRY AIR ALOFT WHICH IS ENHANCING LOW-MID LEVEL LAPSE RATES...AND

AMPLE LOW LEVEL MOISTURE IS CONTRIBUTING TO MODERATE INSTABILITY

WITH MLCAPE OF 1500-2500 J/KG.  AREA VAD AND WIND PROFILER DATA SHOW

30 KT NELY WINDS ABOVE 3-4 KM WHICH WILL PROMOTE SWWD STORM

PROPAGATION.  NEW CELLS ARE LIKELY TO DEVELOP PREFERENTIALLY ALONG

THE WRN OUTFLOWS OF EXISTING STORMS...WITH INCREASING LIKELIHOOD OF

WET MICROBURSTS AS LOW LEVEL HEATING STEEPENS LAPSE RATES BELOW 1

KM.  IN ADDITION...OTHER STORMS ARE EXPECTED TO DEVELOP OVER NRN MS

THIS AFTERNOON AND MOVE TOWARD THE NRN PARTS OF THE WW.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM

MOTION VECTOR 04025.





...WEISS

