570  
WWUS20 KWNS 020248  
SEL0  
SPC WW 020248  
IAZ000-MNZ000-NEZ000-SDZ000-021000-  
 
URGENT - IMMEDIATE BROADCAST REQUESTED  
SEVERE THUNDERSTORM WATCH NUMBER 640  
NWS STORM PREDICTION CENTER NORMAN OK  
945 PM CDT TUE SEP 1 2026  
 
THE NWS STORM PREDICTION CENTER HAS ISSUED A  
 
* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF  
NORTHWEST INTO NORTH-CENTRAL IOWA  
SOUTHWEST INTO SOUTH-CENTRAL MINNESOTA  
FAR NORTHEAST NEBRASKA  
EXTREME SOUTHEAST SOUTH DAKOTA  
 
* EFFECTIVE THIS TUESDAY NIGHT AND WEDNESDAY MORNING FROM 945 PM  
UNTIL 500 AM CDT.  
 
* PRIMARY THREATS INCLUDE...  
SCATTERED DAMAGING WINDS LIKELY WITH ISOLATED SIGNIFICANT GUSTS  
TO 75 MPH POSSIBLE  
SCATTERED LARGE HAIL AND ISOLATED VERY LARGE HAIL EVENTS TO 2  
INCHES IN DIAMETER POSSIBLE  
A TORNADO OR TWO POSSIBLE  
 
SUMMARY...SEVERE THUNDERSTORM CURRENTLY MOVING THROUGH EXTREME  
SOUTHEAST SOUTH DAKOTA IS EXPECTED TO CONTINUE NORTHEASTWARD  
TONIGHT, TRACKING THROUGH SOUTHWEST MINNESOTA AND NORTHWEST IOWA.  
STRONG WIND GUSTS FROM 65 TO 75 MPH ARE POSSIBLE WITH THIS STORM.  
ADDITIONAL THUNDERSTORMS ARE DEVELOPMENT ACROSS SOUTH-CENTRAL  
MINNESOTA. SOME LARGE HAIL IS POSSIBLE WITH THESE STORMS OVER THE  
NEXT HOUR OR TWO. A LONE SUPERCELL IS ALSO PROGRESSING NORTHEASTWARD  
ACROSS FAR NORTHEAST NEBRASKA, WITH AN ATTENDANT THREAT FOR DAMAGING  
GUST AND LARGE HAIL IT IS GRADUALLY MOVES NORTHEASTWARD.  
 
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 45  
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 40 MILES NORTH  
NORTHWEST OF SIOUX CITY IA TO 35 MILES NORTH NORTHEAST OF MASON CITY  
IA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH  
OUTLINE UPDATE (WOUS64 KWNS WOU0).  
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...  
 
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 638...WW 639...  
 
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO  
2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65 KNOTS. A  
FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION VECTOR  
24035.  
 
...MOSIER  
 
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