

000 

WWUS20 KWNS 140414

SEL9

SPC WW 140414

NDZ000-SDZ000-141000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 269

NWS STORM PREDICTION CENTER NORMAN OK

1115 PM CDT SUN MAY 13 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN NORTH DAKOTA

       NORTHWESTERN SOUTH DAKOTA



EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 1115 PM UNTIL

500 AM CDT.



HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70

STATUTE MILES EAST AND WEST OF A LINE FROM 55 MILES EAST

NORTHEAST OF WILLISTON NORTH DAKOTA TO 45 MILES SOUTH SOUTHWEST

OF LEMMON SOUTH DAKOTA.  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.



DISCUSSION...MCS OVER ERN MT CONTINUES TO MOVE EWD INTO WRN ND/NWRN

SD WITH STRONG COLD POOL ESTABLISHING DERECHO TYPE ACTIVITY INTO THE

WRN COUNTIES OF ND.  AIR MASS OVER SWRN ND/NWRN SD IS MODERATELY

UNSTABLE WITH MLCAPE TO 1500 J/KG.  VERY STEEP LAPSE RATES ARE

PRESENT ACCORDING TO 00Z RAOB DATA WITH VALUES AROUND 8C/KM.

THUS...DAMAGING WINDS ARE EXPECTED TO CONTINUE WITH THIS ACTIVITY

ACCOMPANIED BY LARGE HAIL.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM

MOTION VECTOR 25035.





...MCCARTHY

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