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WWUS20 KWNS 031630

SEL7

SPC WW 031630

LAZ000-MSZ000-CWZ000-032100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 217

NWS STORM PREDICTION CENTER NORMAN OK

1130 AM CDT THU MAY 3 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHEAST LOUISIANA

       SOUTHERN MISSISSIPPI

       COASTAL WATERS



EFFECTIVE THIS THURSDAY MORNING AND AFTERNOON FROM 1130 AM UNTIL

400 PM CDT.



HAIL TO 2 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 65

STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES SOUTH

SOUTHEAST OF NEW ORLEANS LOUISIANA TO 35 MILES WEST NORTHWEST OF

PINE BELT MISSISSIPPI.  FOR A COMPLETE DEPICTION OF THE WATCH SEE

THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



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...STRONG/SEVERE STORMS CONTINUE TO INTENSIFY ALONG OLD

OUTFLOW BOUNDARY MOVING EWD INTO SERN LA.  AIR MASS IS MARGINALLY

UNSTABLE WITH MLCAPES 700-800 J/KG WITH DEEP LAYER SHEAR 30-40 KT.

RUC MODEL SOUNDINGS SHOW SUFFICIENT LAYER OF DRYING IN THE LOW/MID

LEVELS WHERE SOME OF THIS ACTIVITY COULD PRODUCE DAMAGING WINDS.

ALSO...THE DATA INDICATES THAT MID LEVEL LAPSE RATES ARE 6.5-7C/KM

WHICH IS SUFFICIENT FOR HAIL WITH THESE STORMS.



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

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 400. MEAN STORM

MOTION VECTOR 24035.





...MCCARTHY

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