

000 

WWUS20 KWNS 281936

SEL1

SPC WW 281936

COZ000-NEZ000-SDZ000-290300-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 81

NWS STORM PREDICTION CENTER NORMAN OK

135 PM MDT WED MAR 28 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       EXTREME NORTHEAST COLORADO

       WESTERN NEBRASKA

       SOUTHWEST SOUTH DAKOTA



EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 135 PM UNTIL

900 PM MDT.



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 70 STATUTE

MILES EAST AND WEST OF A LINE FROM 85 MILES NORTH NORTHEAST OF

CHADRON NEBRASKA TO 10 MILES SOUTHEAST OF IMPERIAL NEBRASKA.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU1).



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 80...



DISCUSSION...INITIAL THUNDERSTORM DEVELOPMENT IS COMMENCING ALONG

THE SURFACE TRIPLE POINT NEAR SCOTTS BLUFF.  CONVECTION WILL LIKELY

INCREASE ACROSS WRN NEB THROUGH THE AFTERNOON AS THE LOW LEVELS

CONTINUE TO WARM/DESTABILIZE...AND ADDITIONAL CONVECTION SHOULD

DEVELOP/SPREAD NWD/NNEWD INTO SW SD.  VERTICAL SHEAR IS ALREADY

QUITE FAVORABLE FOR SUPERCELLS...AND SHOULD REMAIN STRONG THROUGH

THE EVENING TO THE E/NE OF THE PRIMARY SURFACE CYCLONE.  GIVEN

BOUNDARY LAYER DEWPOINTS IN THE LOW-MID 50S AND SUBSTANTIAL

LOW-LEVEL SHEAR...THE SUPERCELLS WILL BE CAPABLE OF PRODUCING

TORNADOES AND LARGE HAIL.  ALSO...CONVECTION MAY GROW INTO ONE OR

MORE LINE SEGMENTS BY LATE AFTERNOON/EVENING THROUGH STORM

MERGERS...WITH THE POTENTIAL FOR A FEW BOWING SEGMENTS WITH 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

450. MEAN STORM MOTION VECTOR 19045.





...THOMPSON

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