865  
ACUS11 KWNS 132011  
SWOMCD  
SPC MCD 132011  
SDZ000-WYZ000-132145-  
 
MESOSCALE DISCUSSION 1939  
NWS STORM PREDICTION CENTER NORMAN OK  
0311 PM CDT WED AUG 13 2025  
 
AREAS AFFECTED...PORTIONS OF NORTHEASTERN WYOMING INTO WESTERN SOUTH  
DAKOTA  
 
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE  
 
VALID 132011Z - 132145Z  
 
PROBABILITY OF WATCH ISSUANCE...60 PERCENT  
 
SUMMARY...THE SEVERE THREAT IS INCREASING ACROSS PORTIONS OF THE  
NORTHERN PLAINS. SEVERE WIND AND HAIL ARE THE MAIN THREATS, WITH AN  
ORGANIZED WIND THREAT LIKELY IF STORMS MERGE INTO AN MCS.  
 
DISCUSSION...A MULTICELLULAR CLUSTER HAS DEVELOPED ACROSS NORTHERN  
WY, AND IS GRADUALLY INTENSIFYING (BASED ON INCREASING LIGHTNING  
TRENDS) AS A MID-LEVEL VORT MAX TRAVERSES THE NORTHERN ROCKIES. AS  
SUCH, THE ONGOING CONVECTION SHOULD PERSIST AS IT PROGRESSES INTO SD  
OVER THE NEXT FEW HOURS. WITH THE APPROACH OF THE VORT MAX,  
DEEP-LAYER SHEAR SHOULD CONTINUE TO STRENGTHEN, WITH WIDESPREAD 40  
KTS OF EFFECTIVE BULK SHEAR LIKELY. AT THE SAME TIME, MLCINH WILL  
CONTINUE TO ERODE AS SURFACE TEMPERATURES CLIMB INTO THE 90S F AMID  
UPPER 50S F DEWPOINTS IN WESTERN SD, BOOSTING MLCAPE TO 1000 J/KG.  
 
THE COMBINATION OF THIS BUOYANCY AND MAINLY ELONGATED HODOGRAPHS  
WILL ENCOURAGE CONTINUED MULTICELLULAR DEVELOPMENT AND PERHAPS  
PRECEDING SUPERCELLS, ACCOMPANIED BY BOTH A SEVERE WIND AND HAIL  
THREAT. WITH TIME THOUGH, UPSCALE GROWTH INTO AN MCS IS POSSIBLE,  
PARTICULARLY IN WESTERN SD. THIS MCS WILL THEN APPROACH A MORE MOIST  
LOW-LEVEL AIRMASS WHILE TRAVERSING A SURFACE BOUNDARY, WITH SURFACE  
DEWPOINTS WELL INTO THE 60S F, WHICH WILL ENCOURAGE FURTHER  
STRENGTHENING AND ASSOCIATED POTENTIAL FOR SOME WIND SWATH  
ORGANIZATION. AS SUCH, A SEVERE THUNDERSTORM WATCH WILL EVENTUALLY  
BE NEEDED, WITH TIMING OF WATCH ISSUANCE REMAINING THE PRIMARY  
QUESTION.  
 
..SQUITIERI/MOSIER.. 08/13/2025  
   
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
 
 
ATTN...WFO...ABR...UNR...CYS...  
 
LAT...LON 43370479 43720523 44130546 44500554 44760552 44900540  
44900353 44640094 44339997 43859975 43469988 43190048  
43090141 43090226 43080304 43210406 43370479  
 
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH  
MOST PROBABLE PEAK WIND GUST...65-80 MPH  
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN  
 
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