129  
WWUS20 KWNS 160049  
SEL1  
SPC WW 160049  
SDZ000-WYZ000-160700-  
 
URGENT - IMMEDIATE BROADCAST REQUESTED  
SEVERE THUNDERSTORM WATCH NUMBER 421  
NWS STORM PREDICTION CENTER NORMAN OK  
650 PM MDT SUN JUN 15 2025  
 
THE NWS STORM PREDICTION CENTER HAS ISSUED A  
 
* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF  
WESTERN AND CENTRAL SOUTH DAKOTA  
FAR NORTHEAST WYOMING  
 
* EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 650 PM  
UNTIL 100 AM MDT.  
 
* PRIMARY THREATS INCLUDE...  
WIDESPREAD DAMAGING WINDS AND ISOLATED SIGNIFICANT GUSTS TO 85  
MPH LIKELY  
ISOLATED VERY LARGE HAIL EVENTS TO 2 INCHES IN DIAMETER POSSIBLE  
 
SUMMARY...AN ORGANIZED WIND-PRODUCING SQUALL LINE IS FORECAST TO  
ORGANIZE AND MOVE EAST ACROSS A LARGE PORTION OF THE WATCH AREA THIS  
EVENING INTO THE OVERNIGHT. A FEW SUPERCELLS WITH AN ATTENDANT RISK  
FOR LARGE HAIL ARE POSSIBLE THIS EVENING OVER SOUTHERN SOUTH DAKOTA.  
AS THE SQUALL LINE DEVELOPS AND MOVES EAST WITHIN A VERY FAVORABLE  
LAPSE RATE ENVIRONMENT, EXPECTING SEVERE GUSTS (60-85 MPH) TO  
ACCOMPANY THE STRONGER SURGES OF OUTFLOW ASSOCIATED WITH THE  
THUNDERSTORM COMPLEX.  
 
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 95  
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 75 MILES WEST NORTHWEST  
OF RAPID CITY SD TO 30 MILES EAST NORTHEAST OF PIERRE SD. FOR A  
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE  
UPDATE (WOUS64 KWNS WOU1).  
 
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 418...WW 419...WW 420...  
 
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO  
2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 75 KNOTS. A  
FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM MOTION VECTOR  
27035.  
 
...SMITH  
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