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054 

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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