Storm Prediction Center Mesoscale Discussion 1120

   Mesoscale Discussion 1120
   NWS Storm Prediction Center Norman OK
   1200 PM CDT Sat Jun 13 2026

   Areas affected...portions of northern Lower Michigan

   Concerning...Severe potential...Watch unlikely 

   Valid 131700Z - 131830Z

   Probability of Watch Issuance...20 percent

   SUMMARY...An isolated threat for large hail, damaging wind gusts,
   and perhaps a brief tornado may develop over the next 1-2 hours
   across portions of northern Lower Michigan.

   DISCUSSION...A broken band of thunderstorms has developed along a
   weak confluence zone immediately downstream of a subtle, mid-level
   shortwave trough evident over northern Lake Michigan in latest GOES
   water vapor imagery. Northward moist advection ahead/south of this
   band has resulted in surface dewpoints increasing to near 60 F, with
   temperatures warming into the mid-70s. Modifying the 12z APX
   observed sounding for these conditions suggests that weak buoyancy
   has developed as of early afternoon, with around 500 J/kg MLCAPE
   (locally up to 1000 J/kg per latest objective analysis). While
   further destabilization is not expected to be substantial, strong
   mid-level flow (50-60 kts sampled by the APX VWP at 2-3 km AGL) and
   effective shear of 50-60 kts will support updraft organization as
   ongoing convection evolves east-southeastward across northern Lower
   Michigan over the next 1-2 hours.

   Despite generally weak instability, the strong effective shear,
   modestly steep mid-level lapse rates (around 7 C/km per latest
   mesoanalysis), and steepening low-level lapse rates will promote
   some potential for isolated large hail and damaging wind gusts with
   any convection that can become better organized. A brief tornado
   also cannot be ruled out given 0-1 km SRH of 100-150 m2/s2 sampled
   by the APX VWP and indicated by latest objective analysis. Watch
   issuance appears unlikely at this time owing to the expectation for
   the severe risk to remain isolated and limited in magnitude.

   ..Chalmers/Mosier.. 06/13/2026

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...APX...

   LAT...LON   44978298 44748301 44518307 44338316 44228338 44188375
               44198416 44258455 44338480 44478497 44788511 45028505
               45198491 45278464 45408414 45428373 45368344 45208317
               44978298 

   MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
   MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
   MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN