

313 

WWUS20 KWNS 041901

SEL0

SPC WW 041901

AZZ000-CAZ000-NVZ000-UTZ000-050200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 690

NWS STORM PREDICTION CENTER NORMAN OK

105 PM MDT MON OCT 4 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PART OF NORTHWEST ARIZONA

       PARTS OF SOUTHEAST CALIFORNIA

       PARTS OF SOUTHERN NEVADA

       SMALL PART OF SOUTHWEST UTAH



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 105 PM UNTIL 800

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 115

STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES NORTH OF

CEDAR CITY UTAH TO 65 MILES SOUTHWEST OF NEEDLES CALIFORNIA.  FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU0).



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...THUNDERSTORMS ARE INCREASING IN NUMBER AND INTENSITY

ACROSS THE WATCH AREA IN ADVANCE OF DEEPENING UPPER TROUGH OVER CA.

GIVEN THE STEEP LAPSE RATES AND MLCAPES TO 1000 J/KG...SEVERE

THUNDERSTORMS WILL BE A POSSIBILITY THROUGH THE AFTERNOON.  PRIMARY

THREAT WILL BE LARGE HAIL AND BRIEF 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 500. MEAN STORM

MOTION VECTOR 22025.





...HALES

