Sunday, June 28, 2009

Severe Thunderstorm Watch


   URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 530
NWS STORM PREDICTION CENTER NORMAN OK
135 PM EDT SUN JUN 28 2009

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

NORTHERN AND CENTRAL ALABAMA
WESTERN AND CENTRAL GEORGIA
SOUTHEAST TENNESSEE

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 135 PM UNTIL 900
PM EDT.

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 135
STATUTE MILES EAST AND WEST OF A LINE FROM 50 MILES SOUTH
SOUTHWEST OF COLUMBUS GEORGIA TO 55 MILES NORTHEAST OF HUNTSVILLE
ALABAMA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0).

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 ARE BEGINNING TO FORM ACROSS PARTS OF
TN/AL/GA IN AXIS OF VERY MOIST AND UNSTABLE AIR. PWAT VALUES OVER 2
INCHES...MLCAPE OF 3000+ J/KG AND ABOUT 20 KNOTS OF EFFECTIVE SHEAR
WILL PROMOTE SLOW-MOVING MULTICELL STORM CLUSTERS CAPABLE OF WET
MICROBURSTS.

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 500. MEAN STORM
MOTION VECTOR 32020.


...HART

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