textproduct: Detroit/Pontiac

KEY MESSAGES

- Temperatures closer to normal and drier today, followed by additional rainfall late Thursday afternoon into early Friday morning.

- A strong cold front delivers gusty winds and much chillier conditions Friday, with a few showers in spots.

- Turing drier through the weekend with slightly warmer readings by Sunday.

DISCUSSION

Remnants of overnight showers/storms vacate the area early this morning as upper Midwestern high pressure builds in the from north. Elevated portions of the weak cold front in northern Ohio are slowly pushed south over the course of the morning which could still allow a spotty light shower/drizzle through mid-morning along the state border. Otherwise dry conditions are established across SE MI today with cool northerly flow bringing temperatures back closer to averages, albeit still some 5 degrees warmer than mid-October normals.

Influence of high pressure wanes over the course of Thursday morning as it tracks towards Quebec. While this occurs, a southern stream mid-upper trough ejects at out the 4-corners region over the central Plains phasing with a northern stream trough digging out of Manitoba. Timing of lead rain has come into better focus with this cycle of runs with showers expected to expand southwest to northeast over the course of the late afternoon-evening (~20-00Z) as the elevated warm frontal slope lifts into SE MI. A few rumbles of thunder possible by late evening towards the Ohio border area as the surface warm front lifts north towards M-59 allowing at least a few hundred J/kg of elevated instability to build over the state line. Surface low progged to slide directly over the area Thursday night coinciding the bulk of rain coverage/QPF with rainfall totals generally falling in the 0.25-0.5" range.

Synoptic rain tapers off Friday morning as the low pushes deeper into southern Ontario. That said, parent upper trough swings across the west/central Great Lakes during the day ushering in significant cold air aloft (500mb temps fall in the -20's C) steepening lapse rates, which in combination with passing upper divergence, offers scattered convective shower chances. Increasing mixing depths within post-frontal cold advection looking capable to partially, if not fully, tap into 30-35kt flow aloft supporting wind gusts of 30-35mph with potential to peak in the 35-40mph range. Core of this colder airmass reaches the area overnight, marked by 850mb temps falling to around -3C. The edge of Plains surface high pressure attempts to nose into southern MI Friday night as well promoting clearing skies and diminishing winds going into early Saturday morning. As such, setup is favorable for the first freeze for a portion of SE MI as lows bottom in the lower 30s, especially north of M-59 where sub- freezing temperatures are most likely. Below normal temperatures are short-lived however as central CONUS upper ridging expands overhead Sunday returning temps near to above normal for the first half of the new week.

MARINE

Northwest flow takes hold today in the wake of a cold front which will bring localized stronger winds and gusts across Lake Huron where fetch is more favorable. Wind gusts ranging between 20 to 25 knots are expected across north and central Lake Huron through the early evening hours. A high pressure system will then fill in across the northern Great Lakes starting tonight, which will diminish wind speeds leading into tomorrow morning. Lighter winds hold through Thursday as winds veer from east to southwest as high pressure departs.

Attention will then turn to the passage of a low pressure system and subsequent strong cold front, slated to move over the Great Lakes Friday. The initial passage of the low pressure system will likely bring numerous to widespread rain showers in the morning. Passage of the low will usher in a strong cold front that will usher in cooler Canadian air. The strong increase in instability as cooler air filters in over the warmer lake waters coupled with prolonged northwest fetch brings high confidence to see gust to gales across Lake Huron and the Saginaw Bay, and likely south into Lake St. Clair and Lake Erie. Gale Watches have been issued for Lake Huron this forecast package with the potential said watches are expanded over Lakes St Clair and Erie in future updates.

PREV DISCUSSION

Issued at 1105 PM EDT Tue Oct 13 2026

AVIATION...

Post-frontal cool advection will allow stratus to continue expanding southeastward from Mid MI across the Saginaw Valley and Thumb through Wednesday morning. Highest confidence in MVFR ceilings is at KMBS and KFNT. Meanwhile, a disturbance aloft brings scattered showers and lower VFR cloud across the rest of SE MI during the early morning hours, with isolated thunderstorms possible mainly south of M-59. Based on latest trends with guidance and the cluster of storms upstream, did include a thunder mention in the Metro Detroit TAFs. Light NNW wind early Wednesday veers N and NE by Wednesday evening as high pressure builds into the northern Great Lakes. Inbound dry air favors scattering of lower ceilings by late afternoon, with potential for Lake Huron stratus to then move inland Wednesday night.

D21/DTW Convection...A cluster of elevated thunderstorms over southern Lake Michigan may hold together as they track into the airspace between 06z and 10z, so opted to include a TEMPO for TSRA.

DTW THRESHOLD PROBABILITIES...

* Moderate for thunderstorms early Wednesday morning.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Gale Watch from Friday morning through late Friday night for LHZ361>363-421-422-441>443-462>464.

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