

376 

WWUS20 KWNS 310444

SEL7

SPC WW 310444

IAZ000-MNZ000-SDZ000-311200-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 637

NWS STORM PREDICTION CENTER NORMAN OK

1145 PM CDT MON AUG 30 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       FAR NORTHWEST IOWA

       SOUTHWEST INTO CENTRAL MINNESOTA

       SOUTHEAST SOUTH DAKOTA



EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 1145 PM

UNTIL 700 AM CDT.



TORNADOES...HAIL TO 1.5 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 60 STATUTE

MILES EAST AND WEST OF A LINE FROM 5 MILES SOUTH OF YANKTON SOUTH

DAKOTA TO 85 MILES NORTHEAST OF REDWOOD FALLS MINNESOTA.  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...THIS TORNADO WATCH REPLACES TORNADO

WATCH NUMBER 636. WATCH NUMBER 636 WILL NOT BE IN EFFECT AFTER

1145 PM CDT.



DISCUSSION...FORCED BAND OF TSTMS ALONG COLD FRONT AND A DOWNSTREAM

CORRIDOR OF MORE DISCRETE STORM ACTIVITY ARE EXPECTED TO SPREAD NEWD

ACROSS AREA OVERNIGHT IN CONCERT WITH A MIDLEVEL VORTICITY MAXIMUM

TRANSLATING NEWD THROUGH NERN SD.  ANOMALOUS INFLOW AIR MASS EXISTS

FOR THE TIME OF YEAR...CHARACTERIZED BY 70 F BOUNDARY LAYER DEW

POINTS AND 0-1 KM SRH OF 400-500 J/KG.  THUS...DESPITE THE PRESENCE

OF MODEST CONVECTIVE INHIBITION...THE OVERALL SETUP WILL REMAIN

FAVORABLE FOR EMBEDDED BOWING AND SUPERCELL STRUCTURES WITH THE

THREAT FOR A COUPLE OF TORNADOES AND DAMAGING WINDS.



AVIATION...TORNADOES AND 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 24035.





...MEAD

