Marine Weather and Tide Forecast for St. Clair Shores, MI

DISCUSSION

Strong PV anomaly rotating through Northern Minnesota this afternoon and through southern Lower Michigan tomorrow, shearing out in the process however. This system and upper level trough will provide upper level support to enhance lake effect snow showers, with potential seeder-feeder mechanism but more likely just increase in inversion depths 7+ kft. However,the airmass is so cold and dry (~ -10 F dew pts in Wisconsin tonight), tough to gauge just how strong the westerly band or bands in between I-69 to I-94 will be tonight into Tuesday morning, as the modest cape/steep low level lapse rates may actually end up being just above the DGZ (see nam soundings), as 850 mb temps plummet into the negative lower 20s. On the flip side, if some of the cape/lift resides in the DGZ, the fluff factor will be extremely high, and if regional GEM solution verifies, 0.05 inches of qpf easily becomes 2+ inches of snow. Its also unknown how persistent the band(s) will be and whether they will be transient enough to help limit amounts. Ultimately, preference is to highlight localized 1-3" amounts of fluffy snow along/in between the I-69/I-94 corridors. Even this afternoon's activity has overachieved a bit, with Flint receiving 4 tenths of an inch through 18z.

Surface trough swinging south from Northern Lower Michigan in the afternoon may tough off some additional snow shower activity, but general subsidence kicking in and 850 mb temps warming into negative mid teens by evening. Despite the northwest flow, can't rule out flurries and isolate snow showers tracking through tomorrow night, as there is still saturation with respect to ice noted in the 1-3 kft layer. On flip side, would expect some pockets/streaks of clearing as well, and will favor colder mins in the 10 to 15 degree, but potential for normally colder sites to dip into the single numbers with the fresh snow.

Short lived ridging during the day on Wednesday before another shortwave/500 mb trough tracks through Wednesday night/Thursday morning. Moisture axis from the Midwest tending to get pinched off, thus just chance pops, as airmass is also not terribly cold with 850 mb temps in the negative high single numbers.

Strong warm advection pattern follows to end the work week before a major cold blast arrives over the Weekend, as full fledged North American trough develops and lingers into next week. 850 mb temps aob -25 C forecasted by Euro/GFS on Monday, making this airmass the coldest of the winter season by far.

MARINE

Breezy conditions continue under the backdrop of cold air advection which will maintain sustained west flow of 20 to 25 knots, with gust potential holding just shy of 30 knots. The latest ice analysis shows portions of the outer Saginaw Bay that remain ice free, thus Small Craft Advisories will continue given wave height potential nearing the four ft. threshold. Portions of the open water from Port Austin down near Port Hope also may have some ice free zones away from the shoreline which can see some elevated wave heights, but the majority of the nearshore zone has some degree of ice, so the decision was made overnight to drop the ongoing Small Craft Advisory. Wind direction will veer to the northwest tomorrow as even colder air drops in across the Great Lakes. This will sustain breezy conditions through Wednesday morning, where a brief ridge of high pressure then decreases wind intensity. Snow showers remain possible with the continued cold.



PREV DISCUSSION
Issued at 105 PM EST Mon Jan 13 2025

AVIATION...

Arctic airmass will maintain MVFR clouds and lake effect flurry/light snow activity through the bulk this TAF period. Timing and intensity of lake effect snow carries general uncertainty in these set ups, but have highlighted a few periods where greater intensity snowfall from lake effect bands may impact terminals.
Ongoing lake effect bands this afternoon are focused more in the FNT/PTK corridor with flurries elsewhere. As lower level winds turn slightly northwest this evening, this corridor of focused lake effect showers will drift southward and potentially affect the southern metro terminals tonight. A stronger upper wave arrives tomorrow morning bringing another period of higher intensity snow showers that will be focused towards the southern metro terminals.
Surface winds into tomorrow remain steady and generally out of the west at 10-15 knots with gusts mostly in the 20-25 knot range.

For DTW... Persistent MVFR ceilings and scattered lake effect flurries/light snow expected this afternoon and evening as lake moisture streams across the area. Best chance to see accumulating lake effect snow showers comes tonight into Tuesday morning.

DTW THRESHOLD PROBABILITIES...

* High for ceiling 5000 feet or less today and tonight.

* High for p-type all snow through the forecast period.



DTX WATCHES/WARNINGS/ADVISORIES
MI...None.
Lake Huron...Small Craft Advisory until 10 PM EST this evening for LHZ421.

Lake St Clair...None.
Michigan waters of Lake Erie...Low Water Advisory until 1 PM EST Tuesday for LEZ444.