WATCHES: Severe Thunderstorm Watch Number 143

WWUS20 KWNS 272230
SEL3
SPC WW 272230
ALZ000-GAZ000-280500-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 143
NWS STORM PREDICTION CENTER NORMAN OK
525 PM CDT SAT APR 27 2013

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
NORTHERN AND CENTRAL ALABAMA
NORTHWEST GEORGIA

* EFFECTIVE THIS SATURDAY AFTERNOON FROM 525 PM UNTIL MIDNIGHT
CDT.

* PRIMARY THREATS INCLUDE...
SEVERAL DAMAGING WIND GUSTS TO 60 MPH POSSIBLE
SEVERAL LARGE HAIL EVENTS TO 1.5 INCHES IN DIAMETER POSSIBLE

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 75
STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES NORTHEAST OF
HUNTSVILLE ALABAMA TO 30 MILES SOUTH SOUTHWEST OF BIRMINGHAM
ALABAMA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 141...WW 142...

DISCUSSION...LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION
DEVELOPING EASTWARD ACROSS THE REGION...ALONG AND JUST SOUTH OF A
SURFACE FRONTAL ZONE ...IS EXPECTED TO CONTRIBUTE TO INCREASING
THUNDERSTORM ACTIVITY DURING THE NEXT FEW HOURS. IN CONJUNCTION
WITH STRONG DEEP LAYER SHEAR...DISCRETE STORMS...INCLUDING ISOLATED
SUPERCELLS...MAY EVOLVE INTO AN EASTWARD PROGRESSING ORGANIZED
CLUSTER OF STORMS BY THIS EVENING. GIVEN SOMEWHAT MARGINAL BOUNDARY
LAYER MOISTURE AND INSTABILITY...THE RISK FOR TORNADOES...WHILE
PERHAPS NOT COMPLETELY NEGLIGIBLE DUE TO SIZABLE LOW-LEVEL
SHEAR...APPEARS RELATIVELY LOW...WITH LARGE HAIL AND DAMAGING WIND
GUSTS PRIMARY SEVERE RISKS.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 50
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM
MOTION VECTOR 25035.


...KERR

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