

482 

WWUS20 KWNS 232152

SEL5

SPC WW 232152

MNZ000-NDZ000-240500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 615

NWS STORM PREDICTION CENTER NORMAN OK

450 PM CDT THU JUL 23 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHWEST MINNESOTA

       EASTERN NORTH DAKOTA



EFFECTIVE THIS THURSDAY AFTERNOON FROM 450 PM UNTIL MIDNIGHT 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 115

STATUTE MILES EAST AND WEST OF A LINE FROM 15 MILES NORTHWEST OF

HALLOCK MINNESOTA TO 75 MILES SOUTH SOUTHEAST OF JAMESTOWN NORTH

DAKOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED

WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).



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 614...



DISCUSSION...THUNDERSTORM DEVELOPMENT IS UNDERWAY ALONG A

PRE-FRONTAL TROUGH IN CENTRAL ND WHERE STRONG SURFACE HEATING HAS

REDUCED CONVECTIVE INHIBITION AND CONTRIBUTED TO MODERATE

INSTABILITY.  ADDITIONAL STORMS WILL FORM DURING THE EVENING INTO NE

ND AND NW MN AS A PRONOUNCED MID LEVEL TROUGH DIGS SEWD FROM

MANITOBA.  THE COMBINATION OF MODERATE INSTABILITY AND STRONG DEEP

LAYER NWLY SHEAR WILL BE SUPPORTIVE OF BOTH SUPERCELLS AND BOWING

SEGMENTS CAPABLE OF PRODUCING DAMAGING WINDS AND LARGE HAIL THROUGH

EARLY TONIGHT.



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 30030.





...THOMPSON

