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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 624

NWS STORM PREDICTION CENTER NORMAN OK

355 PM CDT TUE AUG 17 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       FAR NORTHWEST MINNESOTA

       NORTH DAKOTA

       NORTHWEST AND NORTH-CENTRAL SOUTH DAKOTA



EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 355 PM UNTIL

1100 PM CDT.



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 70

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

OF LEMMON SOUTH DAKOTA TO 25 MILES EAST OF THIEF RIVER FALLS

MINNESOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).



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...TSTMS ARE EXPECTED TO DEVELOP ALONG SEWD MOVING COLD

FRONT WITHIN THE NEXT HOUR OR TWO WITHIN A WARM AND MODERATELY

UNSTABLE AIR MASS WITH MLCAPE OF 1000-1500 J/KG.  THE COMBINATION OF

STEEP LAPSE RATES AND 30-40 KT OF DEEP NWLY SHEAR WILL BE SUPPORTIVE

OF ORGANIZED STORM MODES INCLUDING SUPERCELLS AND BOWING STRUCTURES

WITH THE PRIMARY HAZARDS BEING DAMAGING WIND GUSTS AND SOME HAIL.



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 30030.





...MEAD

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