

000 

WWUS20 KWNS 052021

SEL1

SPC WW 052021

COZ000-NEZ000-SDZ000-WYZ000-060300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 351

NWS STORM PREDICTION CENTER NORMAN OK

220 PM MDT TUE JUN 5 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHEAST COLORADO

       THE WESTERN NEBRASKA PANHANDLE

       EXTREME SOUTHWEST SOUTH DAKOTA

       EASTERN WYOMING



EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 220 PM UNTIL

900 PM MDT.



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 70

STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES NORTH OF

GILLETTE WYOMING TO 20 MILES WEST OF LIMON COLORADO.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU1).



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 347...WW 348...WW

349...WW 350...



DISCUSSION...THUNDERSTORMS ARE EXPECTED TO INCREASE IN

COVERAGE/INTENSITY THIS AFTERNOON ALONG AND E OF THE MOUNTAINS IN

CO/WY...AS WELL AS OVER THE BLACK HILLS IN SD.  SURFACE HEATING HAS

RESULTED IN SOME MIXING OF SURFACE DEWPOINTS INTO THE UPPER 40S

ACROSS SE WY...BUT STEEP LAPSE RATES AND SUBSTANTIAL DEEP LAYER

SHEAR WILL LIKELY SUPPORT A FEW SUPERCELLS LATER THIS AFTERNOON INTO

THIS EVENING.  LARGE HAIL AND ISOLATED DAMAGING GUSTS WILL BE THE

MAIN THREATS THROUGH LATE AFTERNOON.  THERE WILL BE SOME POSSIBILITY

FOR A TORNADO OR TWO BY LATE EVENING OVER THE HIGH PLAINS AS

LOW-LEVEL MOISTURE AND SHEAR INCREASE...MAINLY FROM EXTREME NE CO

INTO THE NEB PANHANDLE /PRIMARILY JUST E OF THIS WATCH AREA/ AFTER

01-02Z.



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 30020.





...THOMPSON

