

534 

WWUS20 KWNS 110456

SEL2

SPC WW 110456

IAZ000-MNZ000-NEZ000-SDZ000-111100-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 622

NWS STORM PREDICTION CENTER NORMAN OK

1155 PM CDT SUN JUL 10 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       NORTHWEST IOWA

       FAR SOUTHWEST MINNESOTA

       FAR NORTHEAST NEBRASKA

       SOUTHEAST SOUTH DAKOTA



EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 1155 PM UNTIL

600 AM CDT.



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 75

STATUTE MILES EAST AND WEST OF A LINE FROM 30 MILES WEST

SOUTHWEST OF SIOUX CITY IOWA TO 20 MILES NORTHWEST OF WORTHINGTON

MINNESOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).



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...WW

620...WW 621...



DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND

INTENSITY DURING THE OVERNIGHT HOURS AS A STRENGTHENING NOCTURNAL

LLJ ENHANCES CONVERGENCE ALONG PRE-EXISTING BOUNDARIES.  THE

PRESENCE OF MUCAPE OF 4000-6000 J/KG AND 30-40 KT OF DEEP WLY SHEAR

WILL BE SUPPORTIVE OF ORGANIZED STORM MODES INCLUDING SUPERCELLS

WITH THE PRIMARY HAZARDS BEING LARGE HAIL AND 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 27025.





...MEAD

