textproduct: Detroit/Pontiac

KEY MESSAGES

- A mix of rain and snow showers will affect the eastern portions of the thumb tonight. Minor accumulations on grassy surfaces are possible.

- Mostly cloudy skies will prevail this weekend with seasonally cool temperatures.

- Dry and mild weather will dominate much of next week.

DTW THRESHOLD PROBABILITIES

* Low for ceilings at or below 5,000 feet tonight, high tomorrow.

PREV DISCUSSION

Issued at 333 PM EST Fri Nov 13 2026

DISCUSSION...

Long wave troughing across eastern N America will dominate the forecast across the Great Lakes region through the weekend. Water vapor imagery shows a secondary mid level wave sliding south across Lake Mi and ern Wisconsin this afternoon. As this wave advances south this evening, a more northerly flow will become established across Lower Mi. This will advect a little drier low level air into Se Mi, offering an opportunity for at least some partial clearing. The latest RRFS and HRRR are strongly supportive in the development of a dominate lake effect band from Sturgeon point across the northeastern thumb late this evening and continuing into at least early Sat morning, affecting locations primarily across E Huron and NE Sanilac Counties. Modified model soundings for 850mb temps of -5 to -6C and lake temps around 10C indicate equilibrium levels of 7 to 9 kt feet within moist mid level air and enhanced boundary layer convergence. While cold enough to contribute to good enhancement off the Lake, the airmass does not appear cold enough to sufficiently cool the boundary layer enough to provide anything more than minor snow accumulations on grassy surfaces within any heavier convective elements. While hi res guidance suggests a narrow axis of precip in the .4 to .8 inch range, thermal profiles suggest precip type being mainly a rain/melting snow mix.

A broad low level cyclonic flow associated with the long wave troughing will hold across Lower Mi through most of the weekend. A backing of the low level flow toward the north-northwest on Saturday will drive the Lake Michigan moisture plume into Se Mi. Model soundings suggest the moisture becoming trapped under a deep low level inversion, likely resulting in mostly cloudy skies into the day Sunday. The moisture depth will become more shallow and thus offer little support for precip. The cloud cover will also limit the diurnal temperature range through the weekend, with daytime highs in the 40s and Sat night lows in the 30s.

Strong high pressure will expand into Lower MI late Sunday/Sunday night, supportive of clearing skies. This high will be associated with a long wave ridge which will become established across the ern US next week. This broad mid level subsidence will result in a persistent low level anticylone across the ern US through much of the week. This pattern will lead to dry and seasonally mild condition across the forecast area Monday through the end of the forecast period.

MARINE...

North to northwest flow remains in place which will support breezy conditions along with lake effect rain through tomorrow. Wind gusts around 20 to 25 knots are expected, with some localized stronger gusts to 30 knots possible across central and southern Lake Huron where fetch is maximized. Small Craft Advisories remain in effect for the Saginaw Bay and Lake Huron shoreline through tomorrow for both these winds and elevated wave heights. This will also be where lake effect rain showers will develop, especially across the southern basin. High pressure to then build in over the Great Lakes starting on Sunday. This will end lake effect precipitation across Lake Huron by the afternoon decrease wind speeds through the day. The influence of high pressure will bring an extended period of dry weather through the midweek along with lighter winds.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Small Craft Advisory until 10 AM EST Sunday for LHZ421-441>443.

Small Craft Advisory until 7 AM EST Saturday for LHZ422.

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