textproduct: Gaylord

KEY MESSAGES

- Periods of showers and storms starting tonight, lasting off and on through the remainder of the period.

- Heavy rain concerns are possible early next week.

DISCUSSION

Issued at 332 PM EDT Fri Aug 7 2026

PATTERN SYNOPSIS/FORECAST:

Difluent flow over the Upper Midwest this morning...with general troughing across the eastern CONUS squeezed between two 597/598dm 500mb highs: one over the Desert SW, and the other over Bermuda. Upper low over central Canada with several niblets of PV swirling through the Canadian Prairies attm, including a shortwave trough axis that stretches from central Ontario down into MN and SD. Broad return flow across the SE US where better moisture (pwats greater than 1.5in) is noted...also sneaking up into the Upper Midwest along/ahead of aforementioned trough axis, along with some weaker stability aloft oozing out of the central Plains, and this is where convective activity is developing this morning. Low level moisture remains on the higher side across the Great Lakes attm, with both 12z/07 MI soundings reporting nearly saturated layers below 600- 700mb below abundant dry air aloft...and quite a bit in the way of low clouds/fog around this morning which finally mixed out around 15- 17z; a few showers already popped up across NE Lower as of 13z, and diurnal cu already underway elsewhere by noonish with some lake breeze development. Nose of 16-20C 850mb temps along and ahead of the aforementioned trough axis and attendant surface boundary from the Central Plains to Lake Superior and up toward James Bay; low/mid- levels cool behind this, to 8C across central Canada (even a tiny bit of 4C air showing up in northern Manitoba attm).

Cyclonic flow aloft remains the theme for the bulk of the next seven days here in the Upper Great Lakes...with upper low over central Canada slowly meandering eastward with time into next week...with potential for another lobe to swing down into central Canada toward midweek or so...and greater uncertainty in the evolution of the forecast beyond this. The bottom line is that it could remain a little more on the unsettled side than not through the next several days...starting with a boundary draping into the area tonight and bringing a shot at showers and thunderstorms into at least part of the day Saturday before washing out in the region. This should become the focus for additional activity later Saturday night into Sunday as another bit of energy swings in...and think this boundary will be very slow to move over the next several days, though various niblets of energy should slide across it at times.

FORECAST DETAILS...

Rain/storms tonight into Saturday morning...think our best shot at activity tonight will be between 6z to 15z or so, along and ahead of the front sliding through...though we should see some activity through the evening, especially across NE Lower where there could be better instability and the lake breeze for convergence...and across the Yoop closer to the forcing and better plume of low-level warm advection. The shortwave trough may turn negatively tilted to our north as it swings through late tonight/early morning, and this could signal a period of better forcing and perhaps a little spicier convection with a slight increase in deep-layer shear toward morning, esp across the Yoop and a marginal 20-30kt LLJ in the vicinity; wouldn't be entirely surprised if we started out the morning with some lingering activity. Otherwise, the nocturnal timing is not typically great for convection, as we should garner some CINH overnight...but think we could still have some low-level instability to work with, and 1000-2000J/kg MUCAPE as well.

Heavy rain concerns ahead???... Stalled/washed-out zonal boundary with periodic perturbations and southwesterly flow certainly seems like a setup worth keeping an eye on for hydro concerns going forward, starting Sunday into Monday ahead of the currently anticipated initial wave. Pwats could reach into the 1.5-2 inch range which is quite moist; signals also point toward potential for some training convection to develop along the perimeter of a plume of weak stability to our southwest. Will need to keep a close eye on this going forward, as there is potential for the convection to track into our area...though it is still possible it could dive to our south...which could drag the whole boundary southward and perhaps limit our heavy rain concerns. The idea of convection on the perimeter of that weak stability axis could also indicate potential for stronger thunderstorms late this weekend into early next week...and will also be something to keep an eye on, though again, better chances could remain to our south.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 146 PM EDT Fri Aug 7 2026

Precipitation is expected to track across Michigan's Eastern Upper Peninsula tonight. -SHRA will pass across KCIU this evening, followed by CIGs lowing to MVFR and IFR mainly between 0600Z and 1200Z Saturday. The remainder of TAF sites are not expected to observe rainfall, but CIGs will lower to MVFR during the overnight hours. Cloud cover will dissipate this Saturday, returning all locations to VFR by the end of the forecast period.

APX WATCHES/WARNINGS/ADVISORIES

MI...None. MARINE...Small Craft Advisory until 10 PM EDT this evening for LMZ344>346.