textproduct: Gaylord

KEY MESSAGES

- Areas of fog tonight into early Thursday morning

- Times of light to moderate rain early Thursday morning will last through Thursday afternoon, less rain for eastern upper

- Brief chances for light rain this weekend, with a general trend of cooler temperatures into next week

- Frost potential early Saturday morning, better chances for widespread frost early next week

DISCUSSION

Issued at 301 PM EDT Wed Sep 30 2026

The first wave of precipitation is moving through northern MI today, dropping around a quarter to just under an inch in areas adjacent to Grand Traverse Bay so far. Lower amounts east of I-75, with only a couple hundredths near Saginaw Bay. Deep moisture is present, with the 12z KAPX RAOB showing a near daily max 1.49 inch PWAT value. Warm rain processes are in action, as the WCD was over 11 kft. Forcing has remained more moderate, keeping rainfall light to moderate at times, and resulting in totals remaining under an inch. This wet airmass will continue overnight and into Thursday as an upper closed low in the desert SW lifts north into the central plains and continues to direct the plume of deep tropical moisture towards the Great Lakes region. At the same time, a larger surface cyclone will continue to track eastward over central CAN. An upper shortwave will help reinforce the southward progression of the cold front Thursday. Above our heads, upper ridging over the SE CONUS will be present Thursday, as well as broad upper troughing over CAN. These join near the Great Lakes region Thursday, placing northern MI in the right entrance region right behind the cold frontal passage, which will be the afternoon and evening of Thursday. Ahead of the front, a 30 - 40 kt LLJ will stretch from MO through southern MI. This will likely remain south of M-55, as the frontal boundary will meet with it late morning Thursday. The front near the surface will track across northern MI in the afternoon hours.

All of this is to say that the timing and positioning of forcing doesn't quiet align for repeated rounds of widespread heavy rain, or even thunderstorms. Areas of fog will be seen tonight into early Thursday morning as the deep tropical moisture continues. Widespread light to moderate rain will be seen with that secondary surge of deep moisture early Thursday morning, adding another quarter to a half inch of rain over northern lower with less over eastern upper. Times of light to moderate rain will continue over northern lower into the morning hours as the boundary aloft moves overhead and meets the LLJ to our south (keeping it south). Midday to the early afternoon hours, isolated heavy rain for spots in northern lower will be possible where the larger scale forcing meets with the lower level forcing. There is also less than 100 j/kg of instability near the surface as drier air starts to work its way in and some peaks of sunshine could warm the surface up enough. This instability is capped in the mid levels, so it would help produce isolated moderate/heavier rain but not much more. Most rain will exit by Thursday evening, with clouds and breezy northwest winds. Winds will diminish over interior spots with partly cloudy skies into Friday morning. Breezy northwest winds will continue around coastal areas.

The surge of cooler air aloft will occur Friday, and could generate some light lake effect rain showers over eastern upper and along and north of M-72. This will likely hold in some moisture near the surface for Friday night into Saturday morning, when the center of a 1025 mb surface high moves directly overhead. Guidance is split on if temperatures will reach freezing or not, as fog and even freezing fog remains possible into early Saturday morning. Lake surface temperatures in the 50s and 60s remain too warm for freezing temperatures along coastal communities.

A quick hitting weak system will track over CAN and bring brief rain chances to eastern upper and near the tip of the mitt late Saturday into Sunday. A cooler CAN airmass will slide over the Great Lakes early next week, with increasing confidence for freezing temps early Tuesday morning (greater than 60% chance for most interior northern lower to dip at or below 32F).

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 735 PM EDT Wed Sep 30 2026

Occasional -DZ occurring at some sites this evening. Otherwise cigs/vsbys should slowly worsen tonight, with IFR/LIFR becoming widespread overnight, just ahead of our next area of rain. Showers are expected at the northern lower MI TAF sites Thursday, especially MBL/APN (MBL should see the heaviest rain). Cigs/vsbys do start to improve by late morning.

Light s to sw winds tonight and Thu morning, veering nw and increasing late Thursday.

APX WATCHES/WARNINGS/ADVISORIES

MI...Beach Hazards Statement until 8 PM EDT this evening for MIZ025- 031-095-096-098. MARINE...Small Craft Advisory until midnight EDT tonight for LHZ348-349. Small Craft Advisory until 5 AM EDT Thursday for LMZ323-341- 342-344>346.