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WWUS20 KWNS 082000

SEL7

SPC WW 082000

COZ000-MNZ000-NEZ000-SDZ000-090400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 737

NWS STORM PREDICTION CENTER NORMAN OK

155 PM MDT TUE SEP 8 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHEAST COLORADO

       A SMALL PART OF WESTERN MINNESOTA

       WESTERN AND NORTHERN NEBRASKA

       CENTRAL AND EASTERN SOUTH DAKOTA



EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 155 PM UNTIL

1000 PM MDT.



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 65

STATUTE MILES EAST AND WEST OF A LINE FROM 30 MILES WEST OF

IMPERIAL NEBRASKA TO 50 MILES NORTHWEST OF ORTONVILLE MINNESOTA.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU7).



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...SFC-BASED TSTMS EXPECTED TO FORM ALONG SD/NEB COLD

FRONT IN THE NEXT HOUR OR SO.  AT THE SAME TIME...MOUNTAIN-INITIATED

STORMS NOW IN SE WY/N CNTRL CO EXPECTED TO MOVE/DEVELOP NEWD AND

INTERACT WITH THE OVER SW NEB.  STG LOW-LVL INSTABILITY AND

MODERATELY SHEARED WIND FIELD SUGGEST POTENTIAL FOR UPSCALE

DEVELOPMENT INTO A LARGE E/SE MOVING CLUSTER OVER WRN NEB.  EMBEDDED

STORMS WILL POSE A THREAT FOR SVR HAIL/WIND INTO TONIGHT.  FARTHER

NE...STORMS/POSSIBLE SUPERCELLS WITH SMALL SCALE BOWS EXPECTED TO

MOVE NEWD MORE OR LESS PARALLEL TO FRONT OVER SD.  THESE MAY YIELD

SVR WIND/HAIL THROUGH EARLY TONIGHT.



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 25030.





...CORFIDI

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