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848 

WWUS20 KWNS 240135

SEL7

SPC WW 240135

IAZ000-MNZ000-NEZ000-SDZ000-240900-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 527

NWS STORM PREDICTION CENTER NORMAN OK

835 PM CDT FRI JUL 23 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       NORTHWEST IOWA

       SOUTHWEST MINNESOTA

       NORTHEAST NEBRASKA

       SOUTHEAST SOUTH DAKOTA



EFFECTIVE THIS FRIDAY NIGHT AND SATURDAY MORNING FROM 835 PM

UNTIL 400 AM CDT.



TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 75 STATUTE

MILES EAST AND WEST OF A LINE FROM 35 MILES NORTHEAST OF

BROOKINGS SOUTH DAKOTA TO 45 MILES WEST SOUTHWEST OF SIOUX CITY

IOWA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED

WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND 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.



OTHER WATCH INFORMATION...CONTINUE...WW 523...WW 524...WW

525...WW 526...



DISCUSSION...GROWING MESOSCALE CONVECTIVE SYSTEM WITH EMBEDDED HP

SUPERCELLS IS IN THE PROCESS OF EVOLVING INTO MORE OF AN OUTFLOW

DOMINANT...WIND PRODUCING QLCS.  HOWEVER...IN THE INTERIM...THE

PRESENCE OF SUPERCELL STRUCTURES WITHIN A MODERATE TO STRONGLY

UNSTABLE AIR MASS AND A MODERATELY STRONG LOW AND DEEP-LAYER SHEAR

ENVIRONMENT SUGGEST A CONTINUED THREAT FOR TORNADOES FOR THE NEXT

COUPLE OF HOURS.  ALSO...LARGE HAIL WILL BE POSSIBLE WITH THE MORE

INTENSE UPDRAFTS...PRIOR TO DAMAGING WINDS BECOMING THE MAIN HAZARD.



AVIATION...TORNADOES AND 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

600. MEAN STORM MOTION VECTOR 28030.





...MEAD

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