WATCHES: Severe Thunderstorm Watch Number 443

WWUS20 KWNS 221958
SEL3
SPC WW 221958
IAZ000-NEZ000-230200-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 443
NWS STORM PREDICTION CENTER NORMAN OK
300 PM CDT FRI JUN 22 2007

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

WESTERN IOWA
SOUTHEASTERN NEBRASKA

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 300 PM UNTIL 900
PM CDT.

HAIL TO 2.5 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 45
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 75 MILES SOUTHWEST
OF COLUMBUS NEBRASKA TO 35 MILES SOUTH SOUTHEAST OF DENISON IOWA.
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 442...

DISCUSSION...VERY UNSTABLE AIR MASS IN PLACE ALONG WEAK SURFACE
CONVERGENCE AXIS EXTENDING FROM W-CENTRAL IA INTO S-CENTRAL NEB.
DESPITE LACK OF UPPER SUPPORT/ENHANCEMENT...DIURNAL HEATING AND WEAK
CONVERGENCE MAY DRIVE ISOLATED THUNDERSTORM DEVELOPMENT LATE TODAY
ALONG THIS AXIS. DEGREE OF INSTABILITY AND MODEST DEEP LAYER SHEAR
INDICATE STORMS MAY BECOME SEVERE QUITE RAPIDLY AND POSSIBLY DEVELOP
LOW TO MID LEVEL ROTATION. PRIMARY THREATS ARE EXPECTED TO BE LARGE
HAIL AND ISOLATED DAMAGING WINDS FROM THE SLOW MOVING STORMS THIS
EVENING.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 26015.

..EVANS

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@PO.UIUC.EDU with
"unsub wx-storm" in the body of your message. For more information write chris@lib.siu.edu.