textproduct: Gaylord

KEY MESSAGES

- Areas of fog this morning over eastern upper

- Slight chance for afternoon showers and storms over NE lower today

- Warmer temperatures and times of showers and storms will begin Saturday and linger through early next week. The potential for repeated rounds of rain could lead to flooding concerns.

DISCUSSION

Issued at 130 AM EDT Thu Aug 27 2026

Currently surface observations and satellite depict low clouds, fog, and intermittent drizzle over the eastern U.P. this morning. In this post-frontal environment, cooler air over the moist maritime Great Lakes airmass has been contributing to the patchy fog and low stratus. This airmass will continue towards northern lower, brining low clouds, patchy fog, and off and on drizzle to some spots through sunrise. 24 hour rainfall totals show a handful of an inch or greater swaths, focused in NE lower and eastern upper. Other places saw a couple hundredths to a half of an inch.

In the upper levels, an upper shortwave is exiting to the east this morning, with drier mid-level air gradually moving in behind this. A larger scale PNA pattern over the CONUS exists today, with upper ridging reaching into the NW Territory. The broad upper low over the Hudson Bay remains anchored in place, keeping MI locked in NW flow aloft. As this drier mid level air continues to march through northern MI today, the weak moisture boundary will reside over NE lower during peak diurnal heating. A few afternoon showers with a storm or two will be possible, as around a couple hundred j/kg of instability exists. NW lower will face drying air and shallow instability, keeping better chances closer to the sunrise side. Minimal shear exists in this marginally unstable atmosphere, keeping the main hazards brief heavy rain and lightning. Storms are expected to form right along an area of lower level convergence as the boundary reaches the lake shore (convergence set up is due to winds over the waters). This could keep most activity off shore, over Lk Huron.

Friday, surface high pressure will be overhead. Light winds and times of sunshine will be seen over northern MI. A couple of stronger storm systems near the Pac NW will attempt to beat the upper ridge over the west down. This in turn, will create a southern extent of the upper jet over the central Rockies, which will produce lee cyclogenesis near CO. Hot and humid central plains air will push northward in the warm sector towards WI Friday. Warmer and wetter conditions will reach northern MI this weekend, with light rain chances starting as early as Saturday evening for eastern upper and parts of NW lower. Warmer temperatures, clouds, light rain, and embedded showers/storms will continue through early next week as the upper level trough takes it time moving across the northern rockies (inducing a couple of lee side lows during this time).

Global ensembles show this pattern in the QPF footprints. Most (ENS/GEFS and their AI counter parts) of them do highlight a bullseye of mean total QPF at 1" or more over northern MI by Wednesday of next week. These courser models will have a tough time with amounts, but can capture where the moisture and forcing will be. There is more of a spread in timing of when the deeper moisture reaches northern MI, as some hold off until Sunday. However by Sunday afternoon, 82% of LREF members have PWATs of at least 1.4" over KGLR. The high confidence in deeper moisture remains through early Tuesday morning, then PWAT spread increases Tuesday into midweek.

Conceptually, the set up has the potential to orient the jet stream parallel to a few warm frontal boundaries that reach northern MI. This could result in training of storms producing heavy rainfall, which would lead to flooding. This is very dependent on the path of surface cyclones, and the warm front has been known to stall just to the south producing ideal conditions for convective initiation, which "eats" the moisture before it has time to reach northern MI. Guidance is pointing towards the synoptic scale forcing to be present to lift these features pretty far north, but that could change as we get closer to the event.

Worse case is repeated rounds of training thunderstorms starting late Saturday and lasting through Tuesday, producing swaths of 2 to 4 inches or more and resulting in flooding. With this said, this worse case is not favored (LREF probs of total QPF are only at 25% for 2 inches or more by Wednesday across parts of norther MI). The when and exactly where of this rain will determine impacts, and that can still change as we remain 4 to 5 days out.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 525 AM EDT Thu Aug 27 2026

MVFR to LIFR conditions will improve this morning with terminals expected to return to VFR by the afternoon, prevailing through the remainder of the issuance period. Northwest winds will be breezy today with gusts 20-25 kts in the afternoon, becoming light tonight. Some BR/FG development late tonight into early Friday morning will be possible, dropping otherwise VFR conditions to IFR or lower at times.

APX WATCHES/WARNINGS/ADVISORIES

MI...None. MARINE...Small Craft Advisory until 10 PM EDT this evening for LSZ321.