textproduct: Detroit/Pontiac

KEY MESSAGES

- Below normal temperatures today with highs only near 60 and lows falling into the 30s. Chance for frost is possible tonight particularly over the Saginaw Valley/Thumb.

- More seasonably average temperatures return for the midweek period with little to no rain chances.

- Much above normal temperatures possible by next Sunday.

DTW THRESHOLD PROBABILITIES

* Low for ceilings at or below 5,000 feet today.

PREV DISCUSSION

Issued at 325 AM EDT Mon Oct 5 2026

DISCUSSION...

Lagged sub 700mb dry air advection will pick up throughout the morning hours as flow trajectories now become increasingly anticyclonic. While not easily discernible in the surface observations, a significant 850mb dewpoint gradient will work across the area in the 12-15z time window that will be correlated with active subsidence and deepening isentropic downglide. Rising 1000- 500mb geopotential heights will support a stable surface anticyclone that will build directly across Lower Michigan today and tonight. Below normal temperatures despite full insolation with highs this afternoon near 60 degrees. Calm wind environment brings the potential for a good radiative cooling night tonight that could allow temperatures to drop down well into the 30s. One item of note is very strong warm advection that will occur immediately upstream of Lake Michigan overnight, where some warm advection cloud could survive and spill down towards Southeast Michigan. Probabilistic output suggests probabilities of reaching less than 37 degrees is at approximately 30-40% only after 4am Tuesday morning. Will defer any frost headlines to future shifts.

The warm advection arrives for Tuesday with no upper level jet forcing and no shortwave energy of note. Forecast soundings show very poor moisture increasing with the warm front aloft that also exhibits very poor lapse rates. Preference is with a dry forecast for the middle of the week as best synoptic scale lift support rides north of Lake Huron. Middle 60s for highs on Tuesday with highs then reaching the low 70s Wednesday. Trough wavelength increases significantly late Wednesday and Thursday that will essentially carve out a cold front over or to the south of Lower Michigan. Static stability is forecasted to remain relatively high above 10.0 kft agl despite some modest uptick in lower level thetae. Could see some sprinkles or some accas/altocumulus Wednesday afternoon.

Persistence forecast looks good for the end of the week with dry conditions and daytime temperatures reaching the upper 60s. A great stretch of prototypical Autumn weather before a significant ridging and warming potential occurs by Day 7 next Sunday.

MARINE...

Northwest cold advection is ongoing this morning as 850 MB temps drop slightly below zero over northern Lake Huron. With water temps around 60 degrees F, this leads to favorable mixing depths reaching around 850 MB. Brief, isolated marginal gusts to gales look likely over northern Lake Huron, but the cold advection is quickly exhausted and the pressure gradient rapidly diminishes this afternoon, supporting winds under 30 knots for the afternoon. Small craft advisories continue for Outer Saginaw Bay to Harbor Beach, as Port Hope observation is supportive of gusts to 25 knots early this morning. Winds quickly diminish further in the evening as a large area of high pressure builds over the central Great Lakes tonight.

A strong southwest warm advection pattern kicks in on Tuesday, and wind gusts around 30 knots are likely be day's end, even as 850 MB temps rising into the upper single digits. Small craft advisories will likely be needed for at least Saginaw Bay.

The main low tracks through northern Ontario and into central Quebec by Wednesday evening, dragging a cold front through the Great Lakes Region. Another solid cold advection blast expected, but northwest wind gusts only look to top out in the 20 to 30 knot range.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory until 8 AM EDT this morning for LHZ421.

Small Craft Advisory until 2 PM EDT this afternoon for LHZ441.

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