textproduct: Detroit/Pontiac

KEY MESSAGES

- Showers are likely with a chance of thunderstorms today.

- Dry weather with near-normal, pleasant temperatures returns for Thursday and Friday.

DISCUSSION

Scattered showers have spread across most of the area overnight as the prefrontal moisture belt has arrived. 850-700 moisture advection is bringing PWATs over 1.7 inches already this morning with around 2 inches slated for this afternoon. Warm sector profiles with a wealth of moisture will lead to poor lapse rates through the day with minimal CAPE values (max values around 200 J/kg). There has been no lightning as of 06Z in the vicinity, but there are some more moderate showers reach up to around 35kft so with the addition of up to a couple hundred J/kg of CAPE this morning and the low level jet flaring up to around 40 knots through the morning and into the afternoon, we could get a few thunderstorms. New SPC Day 1 continues the former Day 2 outlook with Marginal Risk of severe storms clipping Lenawee and Monroe counties. This is the area that could possibly draw up the most instability ahead of the cold front later this afternoon to go with the ample shear present already. Any stronger storm may produce gusty winds with the strong flow just off the deck, and damaging wind would be the primary threat with any severe storms. Heavy rainfall will also be a threat today with any training cells due to high moisture content and potential training along the prefrontal axis.

The prefrontal trough will clear the area by this evening with the cold front following by morning. Won't see a big drop off in temps Thursday (mid to upper 70s) as the thermal trough lags behind the front and will arrive later in the day Thursday, but the dewpoint drop off will make it feel more pleasant with lower humidity. The thermal trough then hangs around a couple days to close out the work week with 850mb temps around 10C. High pressure at the surface and low amplitude longwave ridge will lead to a quiet couple days. Next chance of showers comes late Saturday as the next cold front approaches. At this point both the ECMWF and GFS stall the front over northern MI with the bulk of the forcing holding to the north, so will keep it at a slight chance for now.

MARINE

Moderate southwesterly winds set up this morning as seasonably strong low pressure system tracks across southern Canada into Hudson Bay. While a gust or two two could reach entry-level gales over central Lake Huron, winds are expected to peak around 30kts. Small Craft Advisories are in effect for the Saginaw Bay/tip of the Thumb through this evening as a result. Return of a humid airmass back to the region will support shower and thunderstorm chances for much of the day before the attendant cold front crosses late evening. Moderate northwesterly flow follows for Thursday however only a glancing shot of cold advection and a rapidly diminishing gradient has high pressure builds caps winds aob 30kts. High pressure then drifts overhead through Friday night.

PREV DISCUSSION

Issued at 1156 PM EDT Tue Sep 8 2026

AVIATION...

VFR conditions hold overnight, as a steady increase in mid level moisture commences downstream of an approaching frontal boundary. This moistening will lead to some intervals of light shower production during the early-mid morning hours, particularly from PTK northward. Potential for additional shower development throughout Wednesday as the frontal boundary eases across the area. This may offer some intervals of MVFR conditions - higher probability again from PTK northward. An isolated thunderstorm will be possible, but confidence in occurrence remains too low to mention attm. Prevailing wind from the southwest Wednesday will turning modest gusty into the 20 knot range.

D21/DTW Convection...Thunderstorms are not forecast tonight. Low potential for thunderstorm activity Wednesday afternoon.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling 5000 ft or less Wednesday afternoon.

* Low for thunderstorms on Wednesday.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory from 10 AM this morning to 10 PM EDT this evening for LHZ421-422-441.

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