

533 

WWUS20 KWNS 131946

SEL9

SPC WW 131946

COZ000-NEZ000-WYZ000-140300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 579

NWS STORM PREDICTION CENTER NORMAN OK

145 PM MDT MON JUL 13 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHEAST COLORADO

       WESTERN NEBRASKA PANHANDLE

       EXTREME SOUTHEAST WYOMING



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 145 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 65

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

NORTHWEST OF CHADRON NEBRASKA TO 20 MILES WEST SOUTHWEST OF LIMON

COLORADO.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).



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 576...WW 577...WW 578...



DISCUSSION...SCATTERED THUNDERSTORMS ARE BEGINNING TO DEVELOP TO THE

E OF THE FRONT RANGE IN CO AND THE LARAMIE RANGE IN SE WY.  THIS

AREA LIES ON THE SRN FRINGE OF THE 30-40 KT MID LEVEL FLOW WHERE

VERTICAL SHEAR IS AT LEAST MARGINALLY FAVORABLE FOR ORGANIZED

STORMS/ SUPERCELLS...WITH TEMPERATURES IN THE 80S AND DEWPOINTS IN

THE 55-60 F RANGE CONTRIBUTING TO MODERATE INSTABILITY.  EXPECT

STORM COVERAGE TO INCREASE THROUGH THE AFTERNOON WITH THE POTENTIAL

FOR A FEW STORMS TO PRODUCE LARGE HAIL AND DAMAGING WINDS...AND FOR

STORMS TO PERSIST AS A CLUSTER OR TWO WHILE MOVING FARTHER E LATE

THIS EVENING.



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

