Marine Weather and Tide Forecast for Howell, MI

AVIATION

Surface warm front lifts partially into SE MI this morning as parent low pressure reaches northern Lake Michigan maintaining scattered shower chances into mid-morning (~14-16Z). Can't rule out some embedded thunder though overall potential and coverage are lower relative to earlier this morning so have let the TEMPO mention drop out from running forecast. Ceilings lower towards low VFR-high MVFR early this morning with these showers. Some scattering looks probable over the southern terminals behind this front based on upstream satellite obs over IL/IN however this will be short lived as the attendant cold front quickly sweeps through late morning- early afternoon. Front brings renewed low cloud with additional periods of MVFR cigs as well as much stronger southwest winds as gusts reach around 35kts across the region. Winds steadily weaken overnight with cloud coverage dissipating towards clear or mostly clear.

For DTW...An isolated thunderstorm chance lingers for the first few hours of the new forecast period however overall potential and coverage expected to be lower than earlier this morning. Shower chances end with the arrival the cold front late morning ushering in strong southwest (210-240deg) winds for afternoon-evening as gusts reach near 35kts.

DTW THRESHOLD PROBABILITIES

* High for ceilings at or below 5000 feet by mid-morning into this evening (few hour period late morning for clouds to briefly scatter between fronts). Low tonight.

* Low for thunderstorms between 12Z to 16Z this morning.

PREV DISCUSSION
Issued at 357 AM EDT Mon Apr 21 2025

DISCUSSION...

1003 mb surface low positioned over southern WI early this morning will track to near eastern Lake Superior by evening. Narrow axis of deeper moisture anchored along the inbound associated warm frontal boundary on pace to sweep across southeast Michigan through the morning period. Ascent remains sufficient to support pockets of shower development, with a few rumbles of thunder plausible given presence of weak elevated instability. Early day warm frontal timing affords a short window /15z-18z/ of low level warm/moist advection, before the trailing cold/occluding front sweeps through mid-late afternoon. This will bring temperatures into the 60s. Meaningful surface destabilization will be lacking to support a greater secondary convective response, but isolated sub-severe convection remains possible during this time. Notable increase in gust magnitude occurs within the immediate wake of this fropa, backed by a firm southwest gradient in excess of 20 knots and solid a 30-35 knots comfortably within the the mixed layer. Greatest mixing potential occurs as a few breaks emerge in the cloud initially within the post-frontal environment, but then becomes increasingly compromised as lower cloud increases coverage diurnally. This appears to place a ceiling on prospective gust potential overall to around 45 mph. Gusts of 35 to 45 mph will remain common through the evening hours under sustained cold air advection, despite persist low stratus.

Lower amplitude westerly flow to govern conditions throughout the mid week period. General mid level subsidence atop pervasive surface ridging ensures benign conditions Tuesday, as the resident thermal profile favors temperatures edged on the warmer side of average.
Weak warm frontal boundary lifts into the region Tue night, responding to some increase in southerly flow upstream as weak shortwave energy traverses the central conus. A modest increase in both moisture quality and ascent in the vicinity of this boundary will provide a chance for shower development overnight and possibly into early Wednesday. The onshore flow north of the boundary will maintain notably cooler conditions across the eastern thumb, while southern areas push toward 70 degrees Wednesday. Moderating thermal profile takes an additional upward step Thursday as upper heights build. Prevailing low level southeast flow may offer some Resistance, but projected highs now targeting the low to mid 70s for all locations but the eastern thumb.

MARINE...

Low pressure currently over Wisconsin will lift northeast toward the Straits throughout the day. Several rounds of showers and a few embedded thunderstorms will persist through the morning hours prior to the passage of an occluded front this afternoon. Strong warm advection with this system keeps majority of the waterways stable, although the land-lake interface presents typical concerns for land- based gusts to reach the shoreline. In this case, a short-fused Gale Warning may be necessary if observations warrant. Potential for a period of marginal gales will exist across Saginaw Bay late this afternoon through the evening hours. A Gale Warning now exists for this corridor, while High-end Small Craft Advisories continue highlight the short duration with sporadic gusts to gales elsewhere.
A more favorable setup for gales exists downwind of the Straits into northern Lake Huron early Tuesday morning where colder air temperatures and northwest flow funnel along the fetch. High pressure builds in on Tuesday to support a more benign mid-week pattern.

DTX WATCHES/WARNINGS/ADVISORIES
MI...None.
Lake Huron...Gale Warning from 8 PM this evening to 10 AM EDT Tuesday for LHZ361- 362.

Small Craft Advisory from 8 AM this morning to 2 PM EDT this afternoon for LHZ421-422.

Small Craft Advisory from 10 PM this evening to 10 AM EDT Tuesday for LHZ421-422.

Gale Warning from 2 PM this afternoon to 10 PM EDT this evening for LHZ421-422.

Small Craft Advisory until 10 AM EDT Tuesday for LHZ441>443.

Lake St Clair...Small Craft Advisory from 10 AM this morning to 4 AM EDT Tuesday for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory from 10 AM this morning to 4 AM EDT Tuesday for LEZ444.