087  
ACUS11 KWNS 210317  
SWOMCD  
SPC MCD 210317  
MIZ000-210515-  
 
MESOSCALE DISCUSSION 1686  
NWS STORM PREDICTION CENTER NORMAN OK  
1017 PM CDT MON JUL 20 2026  
 
AREAS AFFECTED...NORTHERN LOWER MICHIGAN  
 
CONCERNING...SEVERE THUNDERSTORM WATCH 505...  
 
VALID 210317Z - 210515Z  
 
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 505  
CONTINUES.  
 
SUMMARY...THROUGH 05Z, THE GREATEST DAMAGING WIND POTENTIAL WILL  
EXTEND FROM GRAND TRAVERSE BAY TOWARD SAGINAW BAY.  
 
DISCUSSION...AS OF 0310Z, RADAR IMAGERY INDICATED A BOWING STORM  
COMPLEX WITH AN ASSOCIATED BOOKEND VORTEX MOVING OVER GRAND TRAVERSE  
BAY. VOLUMETRIC BASE VELOCITY DATA FROM KAPX SUGGEST SOME INDICATION  
OF A REAR-INFLOW JET WITH 50+ KT INBOUND SPEEDS AS LOW AS ABOUT 3  
KFT ABOVE GROUND. RAP-BASED PROXIMITY SOUNDINGS SUGGEST THAT THE  
STORMS ARE SLIGHTLY ELEVATED AND ROOTED WITHIN A MOIST LAYER  
CENTERED AROUND 850 MB. THE STABLE NEAR-SURFACE LAYER IS EXPECTED TO  
LIMIT THE POTENTIAL FOR A MORE CONCENTRATED DAMAGING WIND EVENT.  
HOWEVER, THE SEASONABLY STRONG VERTICAL SHEAR AND INFLUX OF STRONGER  
INSTABILITY FROM THE WEST WILL REMAIN SUPPORTIVE OF STRONG  
UP/DOWNDRAFTS CAPABLE SPORADIC OCCURRENCES OF 60-65 KT WIND GUSTS.  
EXTRAPOLATION OF THE CURRENT SYSTEM MOTION TAKES IT JUST TO THE  
NORTHWEST OF SAGINAW BAY BY 05Z.  
 
..MEAD.. 07/21/2026  
   
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
 
 
ATTN...WFO...DTX...APX...GRR...  
 
LAT...LON 43888448 44338553 44768611 45238597 45398546 44898431  
44368380 44008379 43858405 43888448  
 
MOST PROBABLE PEAK WIND GUST...55-70 MPH  
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN  
 
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