SPC MD 1120

MD 1120 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF NORTHERN LOWER MICHIGAN 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 Read more