

415 

WWUS20 KWNS 191921

SEL3

SPC WW 191921

ALZ000-MSZ000-200200-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 173

NWS STORM PREDICTION CENTER NORMAN OK

220 PM CDT SUN APR 19 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       WESTERN ALABAMA

       SOUTHEAST MISSISSIPPI



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 220 PM UNTIL 900

PM CDT.



TORNADOES...HAIL TO 1.5 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 55 STATUTE

MILES EAST AND WEST OF A LINE FROM 25 MILES NORTHEAST OF

TUSCALOOSA ALABAMA TO 15 MILES EAST SOUTHEAST OF GULFPORT

MISSISSIPPI.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).



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 171...WW 172...



DISCUSSION...SCATTERED THUNDERSTORMS HAVE BEEN SLOWLY INCREASING

OVER SOUTHEAST MS...AHEAD OF PRE-FRONTAL CONVERGENCE AXIS.  VERTICAL

SHEAR REMAINS VERY STRONG IN THIS REGION WITH LOCAL VAD PROFILES

SUGGESTING 300-400 M2/S2 EFFECTIVE HELICITY.  A NARROW AXIS OF

INSTABILITY ALONG AND EAST OF TROUGH MAY ALLOW ISOLATED CELLS TO

INTENSIFY AND BECOME SUPERCELLULAR THIS AFTERNOON AND EARLY EVENING.

 ISOLATED TORNADOES WILL BE POSSIBLE...ALONG WITH DAMAGING WINDS AND

HAIL.



AVIATION...TORNADOES AND 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

450. MEAN STORM MOTION VECTOR 24035.





...HART

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