URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 141
NWS STORM PREDICTION CENTER NORMAN OK
1120 AM CDT FRI APR 15 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
CENTRAL AND SOUTHERN ALABAMA
SOUTHEAST MISSISSIPPI
COASTAL WATERS
EFFECTIVE THIS FRIDAY MORNING AND EVENING FROM 1120 AM 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 65 STATUTE
MILES EAST AND WEST OF A LINE FROM 70 MILES NORTH OF MONTGOMERY
ALABAMA TO 145 MILES SOUTHWEST OF SELMA ALABAMA. FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU1).
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 140...
DISCUSSION...CLUSTER OF SUPERCELLS OVER SERN MS/SWRN AL ARE EXPECTED
TO MOVE/DEVELOP NEWD ACROSS WW AREA WITHIN A DESTABILIZING BOUNDARY
LAYER IN WAKE OF RETREATING WARM FRONT. HERE...THE COMBINATION OF
DEW POINTS RISING THROUGH THE 60S AND DIABATIC HEATING IN THE
BOUNDARY LAYER WILL YIELD AFTERNOON MLCAPE VALUES INCREASING TO
1000-2000 J/KG. THIS INSTABILITY COUPLED WITH RATHER STRONG
LOW-LEVEL SHEAR /I.E. EFFECTIVE SRH VALUES OF 200-400 M2 PER S2/
WILL RESULT IN AN ENVIRONMENT QUITE FAVORABLE FOR SUPERCELLS CAPABLE
OF TORNADOES /SOME SIGNIFICANT/...LARGE HAIL APPROACHING 2.0-2.5
INCHES IN DIAMETER AND DAMAGING WIND GUSTS.
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 24030.
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