Merrill, MI 48637 Weather

This hazardous weather outlook is for southeast Michigan.

Day one: This Afternoon and Tonight

No hazardous weather is expected at this time.

Days two through seven: Thursday through Tuesday

An isolated thunderstorm will be possible Thursday afternoon across Southeast Michigan in advance of a cold front.

Spotter information statement

Spotter activation will not be needed today and tonight.

Key messages

- Mild temperatures continue into Thursday with highs in the 70s. These high temperatures are 10 to 15 degrees above normal.

- There is a chance of showers and an isolated thundestorms Thursday afternoon and Thursday night.

- Dry and continued mild this weekend.

Aviation

Cloud cover increases late tonight into Thursday morning as a cold front pushes east from Wisconsin into Lower Michigan. While moisture quality associated with the front wanes as it encounters a drier airmass and decreasing low level jet influence, remnant moisture will be capable of producing showers initially at MBS as early as ~10z. This decaying band of showers will mark the lead edge of lowering VFR ceilings, which may briefly dip below 3.0 kft right along the frontal passage. Broken shower activity is also expected invof the front, with a low chance of a thunderstorm as lapse rates approach 6.5 C/km. Wind direction will gradually veer from its current southerly direction to southwest Thursday morning before veering more aggressively to the northwest in the afternoon-evening with the frontal passage. Clearing skies and calmer northwest flow emerge late Thursday evening in the post-front environment, although the cooler NW flow will activate moisture flux off the lakes that may result in expansion of low stratus toward the airspace at the end of the TAF period.

D21/DTW Convection: Marginal instability will accompany a cold front passage Thursday afternoon-evening. There is a low chance a few thunderstorms may develop along the front.

Dtw threshold probabilities

* Medium for ceiling at or below 5000 feet Thursday afternoon and evening.

* Low for thunderstorms Thursday afternoon and evening (mainly 20z to 00z).

Prev discussion

Issued at 256 PM EDT Wed Oct 28 2026

DISCUSSION:

A jet exit region and upper level confluent flow will migrate towards the Canadian Maritimes during the next 36 hours. The 1000- 500mb ridge will amplify over Lower Michigan, dampening the effects of a deep shortwave trough lifting out of the Northern Plains to James Bay. Precipitation free conditions can be expected for the remainder of today ahead of the cold front along with temperatures some 15 degrees above normal. A relatively dry cold front draped from the shortwave will push across the forecast area between 18z Thu - 01z Fri.

Relative humidity progs in the plan view show an extremely narrow moisture starved boundary as it pushes across the area, limited to only a few tens of miles across. The current forecast has likely pops of 50-60% percent between 18-00z which is adequate. The overall ageostrophic circulation is expected to be very weak with lean 850- 700mb frontogenesis. Forecast soundings show static stability lingering between 4.0 -7.0 kft agl limiting coverage of activity with MUCAPES of a few hundred J/kg. Latest Swody2 has now introduced General Thunderstorm designation for Southeast Michigan. Warm temperatures are anticipated Thursday ahead of the front with readings pushing into the lower 70s.

Anticyclonic curvature to the zonal jet streak in portions of central Canada will lead to strongly anticyclonic flow curvature over the Great Lakes Friday and Saturday. High confidence exists in strong static stability between 3.0 and 17.0 kft agl. Southeast Michigan will reside in the gradient to the 1000-500mb thickness tempering high temperatures both Friday and Saturday in the lower 60s.

Longwave ridge is forecasted to build across the region this weekend and then continue into the beginning of next week. Current high temperature forecasts suggest temperatures reaching the middle 60s some 7 to 10 degrees above normal. Any pattern change with the arrival of Pacific energy appears to hold off until after Day 7, Tuesday.

MARINE:

Southwest winds will be on the increase tonight ahead of a cold front. However, the warm advection pattern will help limit mixing depths. Nonetheless, the strength of the low level jet and magnitude of the pressure gradient do look to support gusts at or above 25 knots, most prevalent over Central Lake Huron extending back into Saginaw Bay. A Small Craft Advisory has been issued from late tonight through Thursday morning for these wind gusts. Offshore flow, however, should keep waves mostly in the 2 to 4 foot range however.

Behind the cold front, wind speeds look to be maximized over northern Lake Huron where cold advection is most robust. 850 MB temps progged to fall below zero Thursday night, promoting deeper mixing and northwest gusts of 25 to 30 knots. Confidence is high in a period of 25 to 30 knot gusts over northern Lake Huron. High pressure quickly builds into the central Great Lakes Friday afternoon, setting up lighter winds and dry conditions over the weekend.

Watches, warnings and advisories

MI: None. Lake Huron: Small Craft Advisory from 4 AM to 3 PM EDT Thursday for LHZ421-422- 441.

Lake St Clair: None. Michigan waters of Lake Erie: None.