

218 

WWUS20 KWNS 271954

SEL9

SPC WW 271954

LAZ000-MSZ000-280200-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 79

NWS STORM PREDICTION CENTER NORMAN OK

255 PM CDT FRI MAR 27 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       SOUTHWEST INTO CENTRAL LOUISIANA

       EXTREME SOUTHWEST MISSISSIPPI



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 255 PM UNTIL 900

PM CDT.



TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 80 STATUTE

MILES EAST AND WEST OF A LINE FROM 55 MILES EAST NORTHEAST OF

FORT POLK LOUISIANA TO 30 MILES WEST OF LAFAYETTE LOUISIANA.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU9).



REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND 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.



OTHER WATCH INFORMATION...CONTINUE...WW 77...WW 78...



DISCUSSION...A CLUSTER OF STORMS HAS DEVELOPED RECENTLY IN THE

EXTREME SE TX IN THE ERN PART OF WW 77.  STRONG SURFACE HEATING HAS

OCCURRED ACROSS SRN LA IN ADVANCE OF THIS CONVECTION...AND S OF A

SLOW-MOVING OUTFLOW BOUNDARY LOCATED JUST N OF I-10.  THOUGH

BACKGROUND LOW-LEVEL WINDS ARE NOT STRONG...THE BACKED WINDS ALONG

THE BOUNDARY ARE RESULTING IN A RELATIVE MAXIMUM IN LOW-LEVEL SHEAR.

 THIS SOMEWHAT STRONGER SHEAR...COMBINED WITH STRONG SURFACE-BASED

INSTABILITY AND BOUNDARY LAYER DEWPOINTS NEAR 70 F...WILL LIKELY

SUPPORT A CLUSTER OF HP SUPERCELLS ALONG THE BOUNDARY FOR THE NEXT

FEW HOURS.  A COUPLE OF TORNADOES WILL BE POSSIBLE...IN ADDITION TO

LARGE HAIL AND DAMAGING WINDS.



AVIATION...TORNADOES AND 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

500. MEAN STORM MOTION VECTOR 27030.





...THOMPSON

