

231 

WWUS20 KWNS 110312

SEL0

SPC WW 110312

IAZ000-MNZ000-WIZ000-111000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 620

NWS STORM PREDICTION CENTER NORMAN OK

1010 PM CDT SUN JUL 10 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHERN IOWA

       SOUTHERN MINNESOTA

       WESTERN WISCONSIN



EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 1010 PM UNTIL

500 AM CDT.



HAIL TO 1.5 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 90

STATUTE MILES EITHER SIDE OF A LINE FROM 50 MILES SOUTH SOUTHWEST

OF MINNEAPOLIS MINNESOTA TO 55 MILES EAST SOUTHEAST OF ROCHESTER

MINNESOTA.  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.



OTHER WATCH INFORMATION...CONTINUE...WW 618...WW 619...



DISCUSSION...BOWING MCS WITH A HISTORY OF WIDESPREAD DAMAGING WINDS

IS EXPECTED TO CONTINUE SEWD ACROSS THE WATCH AREA OVERNIGHT.  THE

INFLUX OF A VERY MOIST AND UNSTABLE AIR MASS /I.E. MLCAPE OF

1500-2500 J PER KG/ COUPLED WITH 40-50 KT OF DEEP-LAYER SHEAR SHOULD

SERVE TO MAINTAIN VIGOROUS UPDRAFTS ALONG THE LEADING EDGE OF SYSTEM

COLD POOL.  WHILE A BRIEF TORNADO IS POSSIBLE...DAMAGING WINDS AND

SOME HAIL WILL REMAIN THE PRIMARY SEVERE WEATHER HAZARDS.



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

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 28035.





...MEAD

