textproduct: Gaylord

DISCUSSION

Issued at 147 PM EDT Sun Jun 28 2026

A large scale pattern shift ongoing with sizable height falls developing across the western CONUS with downstream height rises pushing ridging northward. The upper pattern becomes more anchored by early this week with a 594 dam upper level high centered over Kentucky with an 850mb thermal ridge extending north and west from the Mississippi Valley into the upper Midwest. As the thermal ridge strengthens and pushes north and eventually east with time, a plume of deeper moisture with PWATs of 150-200% of normal will surge into the Great Lakes.

A myriad of model solutions this week with regard to convective chances on the periphery of the upper ridge, which will play significantly into high temperatures (heat risk potential) and thunderstorm/heavy rain potential. A weak mid level short wave moves eastward tonight into Monday, shearing out as it rides southeast along the moisture/thermal gradient pushing into the Great Lakes. Still questions of how much of this convection will survive as it pushes into Michigan. The best chance of stronger storms would be closer to Lake Michigan, mainly Leelanau to Manistee. The main threat would be hail with any stronger storms, given the elevated instability. Elsewhere, scattered showers and a few thunderstorms possible Monday morning as the wave pushes east within the moisture/thermal gradient.

The remainder of the week features broad southwest flow within a moist and unstable atmosphere. Northern Michigan sits on the eastern/southern edge of better jet dynamics with likely several convective complexes making a run toward the western and northern lakes during this time. To further complicate things, we will also have to contend with an increasingly capped atmosphere, with 700mb temperatures heading toward 15C. Convective evolution this week will be highly dependent on residual boundaries and outflows, with bigger storms possible if we can break through the cap.

High confidence in an uncomfortably hot and humid week in the Great Lakes with heat indices 95 to 100 degrees. Northeast lower Michigan would be the most likely to see the highest heat indices, given the benefit of downsloping with southwest flow. Heat risk on any given day will be largely governed by upstream convection and cloud trends.

Pattern becomes a bit less amplified by late week into the weekend but still quite warm and remaining active with shower/storm chances.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 605 AM EDT Sun Jun 28 2026

Any fog/mist and low clouds will mix out quickly early this morning, leaving behind VFR conditions under some relative high based cumulus. Increasing high clouds this evening gives way to a mid level cloud deck across western taf location early Monday morning. May see a few showers and storms accompany this mid cloud deck, although uncertainty in both coverage and organization remains high. Light winds today with local lake breeze development this afternoon. Light winds for most tonight, although southeast winds do become a bit gusty by early Monday morning at KTVC and KMBL.

APX WATCHES/WARNINGS/ADVISORIES

MI...None. MARINE...Small Craft Advisory from 11 AM to 11 PM EDT Monday for LHZ345>348. Small Craft Advisory from 6 AM Monday to 8 AM EDT Tuesday for LMZ344>346.