Storm Prediction Center Severe Thunderstorm Watch 421

Note:
The expiration time in the watch graphic is amended if the watch is
replaced, cancelled or extended.
Note: Click for Watch Status Reports.

   SEL1

   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

   SEL1

   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

Note:
The Aviation Watch (SAW) product is an approximation to the watch area.
The actual watch is depicted by the shaded areas.

   SAW1 
   WW 421 SEVERE TSTM SD WY 160050Z - 160700Z
   AXIS..95 STATUTE MILES NORTH AND SOUTH OF LINE..
   75WNW RAP/RAPID CITY SD/ - 30ENE PIR/PIERRE SD/
   ..AVIATION COORDS.. 80NM N/S /68WNW RAP - 21ENE PIR/
   HAIL SURFACE AND ALOFT..2 INCHES. WIND GUSTS..75 KNOTS.
   MAX TOPS TO 500. MEAN STORM MOTION VECTOR 27035.

   LAT...LON 45830446 45929972 43179972 43080446

   THIS IS AN APPROXIMATION TO THE WATCH AREA.  FOR A
   COMPLETE DEPICTION OF THE WATCH SEE WOUS64 KWNS
   FOR WOU1.

Watch 421 Status Report Messages:

STATUS REPORT #1 ON WW 421

VALID 160245Z - 160340Z

SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 WNW CDR
TO 45 SSW 2WX TO 55 ESE 4BQ.

..MARSH..06/16/25

ATTN...WFO...UNR...ABR...

&&

STATUS REPORT FOR WS 421 

SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS 

SDC007-019-021-031-033-041-047-055-063-065-071-075-081-085-093-
095-102-103-105-107-117-119-121-123-129-137-160340-

SD 
.    SOUTH DAKOTA COUNTIES INCLUDED ARE

BENNETT 	     BUTTE		 CAMPBELL	     
CORSON		     CUSTER		 DEWEY		     
FALL RIVER	     HAAKON		 HARDING	     
HUGHES		     JACKSON		 JONES		     
LAWRENCE	     LYMAN		 MEADE		     
MELLETTE	     OGLALA LAKOTA	 PENNINGTON	     
PERKINS 	     POTTER		 STANLEY	     
SULLY		     TODD		 TRIPP		     
WALWORTH	     ZIEBACH		 
$$


THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY.  PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.
$$