Marine Weather and Tide Forecast for Croswell, MI

AVIATION

Low pressure in the New England states reaches back into the Great Lakes to maintain unsettled cloud conditions in SE Mi today. A trailing surface trough supports renewed coverage of borderline MVFR/VFR clouds spreading north to south across the area during the morning. There is just enough response to downslope flow for northern Lower Mi IFR clouds to reach low end MVFR while spreading into mbS not long after the 12Z forecast issuance. At least broken MVFR coverage makes it to PTK and then even farther south into the DTW corridor while rising into VFR below 5000 ft. Cloud improvement is limited by continued cool NW flow across Lower Mi tonight while high pressure is slow to move in from the Midwest through sunrise Saturday.

For DTW/D21 Convection... No thunderstorms today or tonight.

THRESHOLD PROBABILITIES...

* Low for ceiling 5000 feet or less this morning. High this afternoon and tonight.

PREV DISCUSSION
Issued at 350 AM EDT Fri May 23 2025

DISCUSSION...

Uninspiring pattern featuring dual upper lows situated atop the sub- tropical jet stream places the Great Lakes region in a low-impact position for today and the weekend. GOES and ASOS data indicate sky clearing is well underway for Southeast Michigan as a feed of drier air filters in from the northwest, notably within the 4-7 kft AGL cloud-bearing layer. This should boost radiational cooling over the next 2-3 hours, heading into sunrise. With 2m dewpoints hovering in the upper 30s to lower 40s, can't rule out some localized patchy frosty, especially west of I-75 where showers and stratocumulus dissipated earlier.

Forecast focus for the daylight hours centers on the coverage of diurnal lake-augmented showers given persistent cyclonic flow aloft.
Although the main surface low is projected to track from Lake Ontario toward Lake Champlain throughout the day, persistent CVA will translate to persistent ascent for scattered showers. Overlap between a better defined VortMax and higher ThetaE low-level air favor higher PoPs/QPF for The Thumb region while subtle mid-level height rises ensue along and south of the M-59 corridor. Made some minor refinements in the NDFD forecast to highlight the aforementioned differences. 850 mb temperatures will moderate incrementally, lifting above the 0C mark for the latter half of the day. This translates into expected high temperatures in the mid to upper 50s for most. Noticeably breezy again today with WNW surface winds, gusting 25 to 30 mph at times as boundary-layer depths increase to 5 kft AGL (800 mb), accessing +25 knot flow. As with daytime highs, overnight lows will be a degree or two warmer tonight (around 40F) with drier conditions, outside of the Lake Huron shoreline.

The northwestern most upper low shears off and retrogrades toward the Minnesota/Ontario border Saturday while the anticyclonic branch of the southern stream jet situates over the southern half of Lower Michigan Saturday. This should effectively mute any additional shower chances, at least for the first half of the weekend, as a more subsident column materializes. Backdrop of gradual warming becomes more pronounced by Sunday as 850 mb temperatures rise into the 1-3C range. Weaker gradient expected while surface winds hold from the northwest. The mid-level low over the Upper Midwest releases across Lower Michigan Sunday offering a somewhat limited opportunity for a final round of isolated to scattered showers, generally north of M-46. Lighter winds and fewer clouds should help boost highs into the mid 60s. Shortwave ridging will be in place early next week with surface high pressure centered over The UP.
Shortwave trough takes aim at the Ohio Valley Tuesday resulting in the next possible synoptic rain event, dependent on how an orphaned north-central CONUS upper low and the resident Great Lakes surface ridge evolve. Latest auto-populated NBM Chance PoPs seem appropriate at this juncture. Temperatures could return to climatological normals as early as Monday with potential for 70F.

MARINE...

A low pressure system will continue to meander across Lake Erie and Lake Ontario today, before phasing with a second low pressure system over New England. This will maintain northwest flow to end the week.
Wind speeds will also gradually weaken in intensity through the weekend as high pressure begins to move in and settle over the Great Lakes. Prior to the arrival of this high pressure system, on and off rain showers will continue to end the week.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None.

Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ421-422.

Lake St Clair...None.

Michigan waters of Lake Erie...None.