

000 

WWUS20 KWNS 212051

SEL3

SPC WW 212051

COZ000-NEZ000-SDZ000-WYZ000-220400-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 333

NWS STORM PREDICTION CENTER NORMAN OK

245 PM MDT WED MAY 21 2008



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHEASTERN COLORADO

       WESTERN NEBRASKA

       EXTREME SOUTHWESTERN SOUTH DAKOTA

       CENTRAL AND EASTERN WYOMING



EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 245 PM UNTIL

1000 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 85

STATUTE MILES EAST AND WEST OF A LINE FROM 45 MILES SOUTH

SOUTHWEST OF AKRON COLORADO TO 40 MILES EAST NORTHEAST OF

SHERIDAN WYOMING.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).



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 332...



DISCUSSION...DAYTIME HEATING AND INCREASING LARGE SCALE

LIFT...ASSOCIATED WITH APPROACHING UPPER TROUGH...WILL RESULT IN

INCREASING STORM INTENSITIES AND COVERAGE THROUGH THE EVENING HOURS.

STRONG DEEP LAYER SHEAR AND MUCAPE VALUES AROUND 1000 J/KG WILL BE

FAVORABLE FOR NWD MOVING SUPERCELLS. THE STEEP LOW/MID LEVEL LAPSE

RATES WILL BE SUPPORTIVE OF HAIL AND DAMAGING WINDS.



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 450. MEAN STORM

MOTION VECTOR 19025.





...IMY

