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WWUS20 KWNS 250148

SEL9

SPC WW 250148

ALZ000-ARZ000-LAZ000-MSZ000-TNZ000-250900-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 709

NWS STORM PREDICTION CENTER NORMAN OK

845 PM CDT SUN OCT 24 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND NORTHERN ALABAMA

       EXTREME SOUTHEAST ARKANSAS

       EXTREME NORTHEAST LOUISIANA

       CENTRAL AND NORTHERN MISSISSIPPI

       A SMALL PART OF SOUTHERN MIDDLE TENNESSEE



EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 845 PM UNTIL

400 AM CDT.



HAIL TO 2 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 75

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 45 MILES NORTHEAST

OF GADSDEN ALABAMA TO 40 MILES SOUTH OF MONTICELLO ARKANSAS.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU9).



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...THIS SEVERE THUNDERSTORM WATCH REPLACES

SEVERE THUNDERSTORM WATCH NUMBER 708. WATCH NUMBER 708 WILL NOT

BE IN EFFECT AFTER 845 PM CDT. CONTINUE...WW 707...



DISCUSSION...A COUPLE OF SCENARIOS EXPECTED TO UNFOLD

OVERNIGHT...WITH LARGE HAIL AND DAMAGING WINDS POSSIBLE IN EACH.

FIRST...ONGOING STORMS ACROSS SE AR/NRN MS WILL LIKELY PERSIST AND

SPREAD EWD TOWARD NRN AL IN ADVANCE OF A SHORTWAVE TROUGH EJECTING

EWD FROM NE TX.  A BROAD UNDISTURBED WARM SECTOR WILL SUPPLY

SUFFICIENT INSTABILITY TO MAINTAIN THE SEVERE THREAT OVERNIGHT...IN

A VERTICAL SHEAR ENVIRONMENT SUPPORTIVE OF EMBEDDED SUPERCELLS AND

BOWS.  THE SECOND THREAT WILL BE A CONTINUATION OF THE SCATTERED

SEVERE STORM/SUPERCELL THREAT ACROSS AL WITHIN THE CONFLUENCE ZONE

AND CORRIDOR OF MOISTURE RETURNING NWD FROM THE GULF OF MEXICO.



AVIATION...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 25025.





...THOMPSON

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