Marine Weather and Tide Forecast for Plymouth, MI

AVIATION

High pressure governs conditions across lower Michigan this afternoon and evening, maintaining light easterly flow and SKC through tonight. Upper level moisture then moves into the region early Sunday morning, with a gradual build down of cloud bases toward 5.0 kft agl. A band of concentrated low level moisture then lifts into the airspace between 09z-13z along an elevated warm front, triggering showers and possibly a rumble of thunder mainly toward mbS/FNT. Less confidence in rain potential exists toward DTW where dry air may cause rain to evaporate before reaching the ground. This also places the best chance for a brief period of MVFR cigs/vsbys over the Saginaw Valley. The surface warm front then lifts into the airspace Sunday afternoon causing winds to veer to the southwest. Gusty winds and scattering low cloud are anticipated as the boundary layer destabilizes.

For DTW... there is a low chance for a rumble of thunder Sunday morning as a band of rain lifts into Lower Michigan. If a thunderstorm does develop, it is most likely between 09z and 13z.

DTW THRESHOLD PROBABILITIES

* Low for ceilings below 5000 ft today. Moderate later tonight into Sunday.

* Low for thunderstorms Sunday morning, mainly between 09z and 13z.

PREV DISCUSSION
Issued at 301 AM EDT Sat Apr 11 2026

DISCUSSION...

Sfc high pressure around 1033mb will become centered over Se Mi by 12Z and will slowly drift east today, associated with a short wave mid level ridge axis. Some lingering strato cu may persist across portions of the area into the morning, tucked under a deep subsidence inversion. Diurnal heating within broad mid level subsidence and a dry ambient airmass will provide ample afternoon sunshine. Subsidence in the mid levels and a residual shallow cold airmass will limit daytime mixing depths to around 4k feet per RAP soundings. This will warrant afternoon highs in the mid 50s, with some cooler readings along the lakeshores.

A strong warm air advection pattern will commence across the Upper Midwest and Great Lakes region tonight into Monday. Enhanced convergence along the nose of the low level jet tonight into early Sunday morning will be focussed across the northern Great Lakes.
This is where rainfall chances will be highest. Mid level warm air advection and moist isentropic ascent will still affect Se Mi overnight into Sunday morning. Residual low level dry air will limit the coverage of showers during the overnight, especially across the south. The lead low level moist axis will then be advection across Se Mi Sunday morning, sustaining a chance for showers. Low level isentropic ascent is forecast to be more persistent across the Saginaw Valley and thumb region, supporting high rain chances in this area. The surface warm sector will lift northward into Se Mi during the day Sunday. Model soundings and probabolistic guidance strongly supports highs well into the 70s in the warm sector. There is some variance among the model suite and their ensembles as to how quickly the warm sector expands into the thumb and Saginaw Valley regions, warranting lower forecast highs north of the I-69 corridor. 30 to 40 knot winds within the well mixed warm sector will warrant windy conditions Sunday. Probabolistic guidance suggest a good potential for gusts to hit 40 MPH south of the I-69 corridor, lower across the north given the likelihood of a later arrival of the warm sector.

Respectable model agrement indicates a mid level short wave impulse and enhanced low level convergence rippling across Lower Mi Sunday night into Monday morning, This will warrant high chances for showers. A reinforcing shot of warm and moist air is then forecast to arrive Monday, with deep layer southwest flow sustaining seasonally warm and humid air through at least mid week. Ensemble spread with respect to timing mid level short wave features and surface fronts leads to uncertainty as to coverage and timing of convection this far out in the forecast. Forecast instability parameters combined with strong wind fields overhead will raise the risk of severe convection through the period. With ample deep layer moisture and the liklihood of slow moving frontal systems, episodes of heavy convective rainfall may also be of concern next week.

MARINE...

High pressure centers over Lower Michigan today ensuring dry conditions with weak winds, at or below 10 knots. The stable system exits east this evening, with return flow eventually flipping winds south-southeasterly with gradual gradient constriction. Active weather returns Sunday morning with gusty showers moving in ahead of a decaying line of nocturnal thunderstorms. Locally higher winds and waves are possible as convection works across the Huron basin.
Several additional rounds of showers and thunderstorms are expected throughout the week due to a series of troughs, low pressure systems, and fronts. Potential still exists for gusts to gales late Sunday into Monday, with the main area of concern being portions of southern Lake Huron. It is possible that the stronger gusts extend further south into Lake St. Clair and western Erie.

DTX WATCHES/WARNINGS/ADVISORIES
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.