

000 

WWUS20 KWNS 052211

SEL9

SPC WW 052211

MNZ000-NDZ000-060500-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 659

NWS STORM PREDICTION CENTER NORMAN OK

510 PM CDT SAT JUL 5 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       NORTHWEST MINNESOTA

       EASTERN NORTH DAKOTA



EFFECTIVE THIS SATURDAY AFTERNOON FROM 510 PM UNTIL MIDNIGHT CDT.



TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 75 STATUTE

MILES EAST AND WEST OF A LINE FROM 20 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 WOU9).



REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND 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.



OTHER WATCH INFORMATION...CONTINUE...WW 658...



DISCUSSION...THE FIRST SURFACE-BASED STORM HAS DEVELOPED IN ERN ND

IN ADVANCE OF A PRE-FRONTAL TROUGH.  BOUNDARY LAYER DEWPOINTS IN THE

UPPER 60S WITH UPPER 80S SURFACE TEMPERATURES HAVE RESULTED IN

STRONG INSTABILITY IN THE WARM SECTOR...AND A SUFFICIENTLY WEAK CAP

TO ALLOW THUNDERSTORM DEVELOPMENT.  ADDITIONAL STORMS WILL LIKELY

FORM THIS EVENING AS AN ASSOCIATED MID LEVEL TROUGH MOVES EWD FROM

ND TO NW MN.  VERTICAL SHEAR AND LOW-LEVEL MOISTURE MAY BE

SUFFICIENT FOR A COUPLE OF TORNADOES THIS EVENING WITH THE DISCRETE

INITIAL STORMS...ALONG WITH LARGE HAIL.  STORMS COULD ALSO EVOLVE

INTO MORE OF A CLUSTER OR LINE SEGMENTS LATER WITH AN ATTENDANT

THREAT FOR DAMAGING WINDS.



AVIATION...TORNADOES AND 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 27025.





...THOMPSON

