

000 

WWUS20 KWNS 101930

SEL7

SPC WW 101930

IAZ000-MNZ000-NEZ000-SDZ000-110300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 377

NWS STORM PREDICTION CENTER NORMAN OK

230 PM CDT SUN JUN 10 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF NORTHWEST IOWA

       PARTS OF SOUTHWEST MINNESOTA

       PARTS OF NORTHERN NEBRASKA

       LARGE PART OF CENTRAL AND EASTERN SOUTH DAKOTA



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 230 PM UNTIL

1000 PM CDT.



HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 90

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 35 MILES SOUTHWEST

OF PHILIP SOUTH DAKOTA TO 40 MILES SOUTHEAST OF REDWOOD FALLS

MINNESOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



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 376...



DISCUSSION...AIR MASS HAS BECOME VERY TO EXTREMELY UNSTABLE ACROSS

CENTRAL AND EASTERN SD.  WITH STEEP LAPSE RATES AND 25-30KT  OF

SHEAR...THUNDERSTORMS EXPECTED TO INCREASE IN BOTH INTENSITY AND

NUMBER ACROSS WATCH AREA THRU THE AFTERNOON.  PRIMARY THREAT WILL

BE LARGE HAIL AND DAMAGING WINDS.  SUPERCELLS ARE POSSIBLE GIVEN THE

INSTABILITY WITH AN ENHANCED SEVERE THREAT.



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

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM

MOTION VECTOR 24025.





...HALES

