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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 559

NWS STORM PREDICTION CENTER NORMAN OK

340 PM CDT SUN AUG 1 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHEAST MONTANA

       NORTHWEST NORTH DAKOTA



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 340 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 60

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 35 MILES SOUTHWEST

OF WOLF POINT MONTANA TO 20 MILES NORTHEAST OF GARRISON NORTH

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.



OTHER WATCH INFORMATION...CONTINUE...WW 558...



DISCUSSION...ISOLATED SUPERCELLS ARE EXPECTED TO PERSIST AND SPREAD

ESEWD FOR SEVERAL HOURS ALONG A REMNANT OUTFLOW BOUNDARY ACROSS NE

MT/NW ND.  SURFACE TEMPERATURES IN THE 80S AND DEWPOINTS IN THE 60S

ALONG AND SE OF THE BOUNDARY ARE SUPPORTING MODERATE

INSTABILITY...WHILE STRAIGHT HODOGRAPHS WITH STRONG DEEP-LAYER SPEED

SHEAR WILL REMAIN FAVORABLE FOR SUPERCELLS.  ISOLATED LARGE HAIL

SHOULD BE THE MAIN THREAT...THOUGH A FEW DAMAGING GUSTS MAY ALSO

OCCUR.



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 450. MEAN STORM

MOTION VECTOR 29030.





...THOMPSON

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