Marine Weather and Tide Forecast for Bay City, MI

AVIATION

There has been a signal for an organized cyclonic/anticyclonic vorticity dipole that will now lead to lowering subsidence between 4.0 and 7.0 kft agl tonight. VFR conditions tonight through Thursday.
A light northerly wind this evening will veer to the southeast tonight and southwesterly Thursday afternoon.

DTW THRESHOLD PROBABILITIES

* None

PREV DISCUSSION
Issued at 353 PM EDT Wed Apr 23 2025

DISCUSSION...

Zonal flow will usher in a series of weak shortwaves along a stalled frontal boundary and bring periodic chances of showers and possible thunderstorms throughout this afternoon and evening. First wave this afternoon targets more central and southern portions of southeast Michigan and then more along and north of the I-69 corridor this evening into tonight. Ongoing lead wave will have some weak daytime instability available, though mesoanalysis keeps greatest instability across lower Michigan south of the front with an associated cu field. There is also a lake boundary providing an additional focal point for possible development. Effective bulk shear is relatively weak, but enough to maintain isolated convection.
Mid level lapse rates up to 6.5-7.0 C/km mainly supports the low potential for thunder and the low hail threat. The dry sub cloud layer may also support an isolated gusty winds. Confidence remains low for any organized activity this afternoon as the elevated showers and clouds will weaken the instability currently present. Even less confidence in the strength of overnight activity with weakening surface instability, but the mid level lapse rates and slightly better overnight shear keeps a low potential.

Weak shortwave ridge will lift into Michigan tomorrow bringing mostly dry conditions. Though, will keep an eye on hi-res trends as there looks to be a boundary pushing off Lake Huron that drops down to the I-69 corridor. This could lead to some pop up showers, maybe a weak thunderstorm, supported by some daytime instability depicted across the Thumb/Saginaw Valley. Will maintain the 15% PoP in these locations to highlight that low possibility. Well above average temperatures will expected again tomorrow with a similar south to north gradient becoming more likely. South of I-69 will be in the upper 70s to low 80s with mostly low-mid 70s north of I-69 and 60s across the northern Thumb given the passage of the front.

There will be a much greater chance for showers and thunderstorms Friday. Low chance for showers exists early Friday morning, but the greater chances will develop late Friday morning into the afternoon as a pair of mid level shortwaves induce a surface low. This surface low will track across Michigan and bringing widespread likely rainfall. Best chance of embedded thunderstorms will be Friday afternoon/evening as better instability develops. Severe threat will be limited, but briefly heavy rainfall will possible given the PWATs of over 1 inch arriving over southeast Michigan. QPF for Friday currently has average totals mostly within the quarter inch to half inch range. As is typical, some locally higher amounts will be possible with any associated thunderstorms. Surface high and upper level ridging takes hold for the weekend keeping conditions dry, but cooler.

MARINE...

A weak pressure pattern across the region promotes light wind through the next couple days. Weakening low pressure tracks across Lake Superior tonight, pulling a warm front across the central Great Lakes with prevailing east to southeast wind shifting to southwest by Thursday morning. The system's cold front then seeps southward across the area on Thursday before stalling across the southern Great Lakes into early Friday. Winds are expected to remain 15 kt or below but the fronts will bring a chance for showers and thunderstorms which may produce locally higher gusts. More organized low pressure will track into the region on Friday with stronger northerly winds possibly leading to Small Craft Advisory conditions on Lake Huron.

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