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000 

WWUS20 KWNS 222043

SEL4

SPC WW 222043

AZZ000-230300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 684

NWS STORM PREDICTION CENTER NORMAN OK

145 PM MST SAT SEP 22 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF ARIZONA



EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 145 PM UNTIL

800 PM MST.



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 50 MILES NORTH

NORTHWEST OF FLAGSTAFF ARIZONA TO 80 MILES SOUTHEAST OF PHOENIX

ARIZONA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).



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...RAPID INCREASE IN THUNDERSTORMS ACROSS CENTRAL AZ IN

RESPONSE TO STRONG SLY FLOW OF MOIST/UNSTABLE AIR.  WITH APPROACH OF

UPPER LOW SRN CA...STORMS EXPECTED TO CONTINUE INTENSIFYING AND

SPREAD NWD WITH LARGE HAIL AND BRIEF DAMAGING WINDS PRIMARY THREAT.



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 19030.





...HALES

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