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900 

WWUS20 KWNS 172019

SEL8

SPC WW 172019

OKZ000-TXZ000-180300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 708

NWS STORM PREDICTION CENTER NORMAN OK

320 PM CDT MON AUG 17 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHWEST OKLAHOMA

       CENTRAL AND EASTERN TEXAS PANHANDLE



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 320 PM UNTIL

1000 PM 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 55

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 25 MILES NORTH

NORTHWEST OF AMARILLO TEXAS TO 10 MILES SOUTH OF ENID OKLAHOMA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU8).



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 HAVE ALREADY DEVELOPED NEAR AMA ALONG A

SURFACE TROUGH...AND ADDITIONAL STORMS MAY FORM FARTHER TO THE ENE

ALONG THE BOUNDARY IN THE NE TX PANHANDLE AS SURFACE HEATING

CONTINUES.  OTHER STORMS COULD ALSO DEVELOP THIS AFTERNOON ALONG A

STALLED OUTFLOW BOUNDARY ACROSS NW OK.  VERTICAL SHEAR IS AT LEAST

MARGINALLY FAVORABLE FOR SUPERCELLS ON THE IMMEDIATE COOL SIDE OF

THE BOUNDARY...ALONG THE N EDGE OF THE STRONGER SURFACE-BASED

INSTABILITY.  CONVECTION SHOULD INCREASE IN COVERAGE AND PERSIST

THROUGH THE EVENING...WITH LARGE HAIL AND DAMAGING WINDS THE MAIN

SEVERE THREATS.



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 550. MEAN STORM

MOTION VECTOR 29015.





...THOMPSON

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