textproduct: Gaylord

KEY MESSAGES

- Thunderstorms likely through the day on Wednesday, a few strong storms and locally heavy rainfall the main concerns.

DISCUSSION

Issued at 110 PM EDT Tue Aug 25 2026

Pattern Synopsis and Forecast:

Upper trough and induced low pressure system will traverse the Upper Midwest tonight, moving eastward with time on Wednesday into N MI. Pressure gradient increases some with the relatively "weak" low pressure system, and thus breezy conditions are anticipated through the day. Main story will be the convective evolution and what that might look like.

Warm advection coupled with upper forcing/divergence within an environment characterized by sufficient moisture and instability will result in scattered to numerous thunderstorms on Wednesday, beginning west of 75 in the morning up into the E UP, then migrating and redeveloping eastward during the afternoon hours. Any stronger storm will be capable of locally gusty winds and hail. Any severe threat looks rather isolated and localized in nature, given the high moisture content and modest shear (25 kts of bulk 0-6km, little more 0-8km, although that can be enough to generate transiently strong storms). Given trough orientation/forcing and instability axis, northeast lower into eastern upper will "likely" see the best opportunity for locally heavy rainfall with training storms. That being said, the atmosphere will be primed with ~1.4"-1.5" PWATs, significant moistening in the low to mid levels, and seemingly more than enough instability for any storm to produce locally heavy rain. Given the low LCLs, weak low level shear, and subtle backing of the low level wind field in areas, an isolated tornado cannot be entirely ruled out but it will not be the primary concern. Limiting factors will be if instability ends up being much less than progged and/or if convection well to our northwest generates a significant cold pool and ruins the convective potential for most of northern lower MI as the boundary is forced eastward quicker. Nevertheless, the signal is there within the suite of hi-res guidance for heavy rain in spots. Localized flooding not out of the question if the ingredients come together just right. Activity diminishes through the night with the loss of daytime heating and the main forcing moving eastward.

Troughing continues to dig down across Ontario late week, impinging lower heights across the Great Lakes Region. Consequently, cooler temperatures are anticipated Thursday into Friday, although close to seasonable for this time of year. Cannot rule out some light showers as well during this time frame and mildly breezy winds.

Heading into this weekend and early next week, ridging builds across the South to Southeast, troughing moves west to east across the N Plains and vicinity, and a more overall zonal structure takes hold for N MI. Consequently, low pressure system to the west will advect moisture eastward into the Midwest, with rounds of rainfall possible. Most likely timing for rain and storms will be Sunday into Monday as moisture advection coincides with upper support. Plenty of uncertainty in regards to the details though. High temperatures seem to hold steady in the upper 70s to low 80s outside of the typical day to day variability given storms and cloud cover.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 143 PM EDT Tue Aug 25 2026

VFR condtions will continue this evening and tonight as high pressure supports mostly clear skies and light winds mainly from the west-southwest. A couple frontal boundary's sweep across Northern Michigan this Wednesday, supporting -SHRA and -TSRA development. MVFR CIGs build into KPLN, KTVC, and KMBL Wednesday morning while ceilings at KCIU will lower to IFR. Skies will improve towards the end of the TAF period, but continued -TSRA will cause temporary flight category reductions.

APX WATCHES/WARNINGS/ADVISORIES

MI...Beach Hazards Statement from late tonight through Wednesday evening for MIZ025-031. MARINE...Small Craft Advisory from 2 AM to 10 PM EDT Wednesday for LHZ345. Small Craft Advisory from 11 AM to 10 PM EDT Wednesday for LHZ348-349. Small Craft Advisory from 2 AM to 10 PM EDT Wednesday for LMZ323-341-342-344>346.