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560 

WWUS20 KWNS 212030

SEL0

SPC WW 212030

COZ000-NEZ000-SDZ000-WYZ000-220400-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 200

NWS STORM PREDICTION CENTER NORMAN OK

225 PM MDT FRI MAY 21 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       NORTHEAST COLORADO

       NEBRASKA PANHANDLE

       FAR SOUTHWEST SOUTH DAKOTA

       EAST-CENTRAL AND SOUTHEAST WYOMING



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 225 PM UNTIL

1000 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 70 MILES NORTHEAST OF DOUGLAS

WYOMING TO 50 MILES EAST OF FORT COLLINS COLORADO.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU0).



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 198...WW 199...



DISCUSSION...DEEPENING LEE TROUGH/CYCLONE IS SUPPORTING THE RAPID

NWWD ADVECTION OF BOUNDARY LAYER MOISTURE INTO THE REGION BENEATH

EML PLUME WITH MLCAPE OF 500-1000 J/KG.  THE INCREASING INFLUENCE OF

WRN U.S. TROUGH AND CONTINUED AIR MASS DESTABILIZATION ARE EXPECTED

TO CONTRIBUTE TO AN INCREASE IN STORMS THIS AFTERNOON INTO EVENING

ALONG SW-NE ORIENTED SYNOPTIC FRONT AND IN THE LEE OF THE HIGHER

TERRAIN.  VERTICAL SHEAR WILL CONCURRENTLY STRENGTHEN...PARTICULARLY

IN THE LOW LEVELS...WITH KINEMATIC ENVIRONMENT BECOMING QUITE

FAVORABLE FOR SUPERCELLS.  INITIALLY...LARGE HAIL WILL BE THE

PRIMARY HAZARD...THOUGH TORNADOES WILL BECOME INCREASINGLY POSSIBLE

BY LATE AFTERNOON/EARLY EVENING WITH THE LOW-LEVEL MOISTURE/SHEAR

INCREASE.



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 24030.





...MEAD

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