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WWUS20 KWNS 221651

SEL2

SPC WW 221651

COZ000-UTZ000-230100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 532

NWS STORM PREDICTION CENTER NORMAN OK

1050 AM MDT SUN SEP 22 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  WESTERN COLORADO

  EASTERN UTAH



* EFFECTIVE THIS SUNDAY MORNING AND EVENING FROM 1050 AM UNTIL

  700 PM MDT.



* PRIMARY THREATS INCLUDE...

  SEVERAL DAMAGING WIND GUSTS LIKELY WITH A FEW SIGNIFICANT GUSTS

    TO 75 MPH POSSIBLE

  A FEW LARGE HAIL EVENTS TO 1.5 INCHES IN DIAMETER POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 110

STATUTE MILES EAST AND WEST OF A LINE FROM 90 MILES NORTH OF

GRAND JUNCTION COLORADO TO 30 MILES SOUTHWEST OF CORTEZ COLORADO.

 FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU2).



PRECAUTIONARY/PREPAREDNESS ACTIONS...



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.



&&



DISCUSSION...TSTMS EXPECTED TO INCREASE IN NUMBER/STRENGTH THROUGH

LATE THIS AFTN IN ZONE OF INCREASING ASCENT AHEAD OF NV SHORTWAVE

TROUGH. ACTIVITY MAY FORM BOTH ALONG AND AHEAD OF ASSOCIATED SFC

COLD FRONT THAT ATTM EXTENDS ROUGHLY SSW-NNE THROUGH CNTRL UT INTO

NW AZ. COMBINATION OF QUASI-LINEAR UPLIFT WITH 40-50 KT SW TO SSWLY

700-500 MB FLOW...AND A THERMODYNAMIC ENVIRONMENT THAT SHOULD BECOME

INCREASINGLY FAVORABLE FOR MICROBURSTS/MOMENTUM TRANSFER...SUGGESTS

THE POTENTIAL FOR BANDS OF STORMS WITH BOWING SEGMENTS/HIGH WIND.

POTENTIAL ALSO WILL EXIST FOR SVR HAIL AND POSSIBLY A BRIEF TORNADO

GIVEN STRENGTH OF SHEAR/INCREASING SFC-BASED INSTABILITY.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM

MOTION VECTOR 21040.





...CORFIDI

