Marine Weather and Tide Forecast for Howell, MI

AVIATION

Cold air circulating around an upper low forecast to track across the northern lakes today will deepen the low level mixing depth.
With 30 knots within the top of the mixed layer, gusty WSW winds will result. The peak winds are forecast during the afternoon and evening hours. Ample low level moisture is also circulating around the upper low and will advance across Se Mi late this morning into tonight. This combined with daytime mixing will likely resulting in fluctations in ceilings heights between low end VFR and MVFR throughout the afternoon and evening.

For DTW/D21 Convection...No thunderstorms are expected through the TAF period.

THRESHOLD PROBABILITIES...

* High in ceilings aob 5000 feet from late morning through Sunday morning.

PREV DISCUSSION
Issued at 400 AM EDT Sat May 17 2025

DISCUSSION...

A cold front passing through early this morning ushers out the last vestiges of the summer-like weather felt over the past few days. The parent low pressure, its mid-level closed circulation now tracking directly into Lower MI, ushers in a much cooler air mass through the day. 850mb temps analyzed near 11C will fall to around 4C by late in the day with diurnal heating dampened by opaque stratus wrapping around the system. The result will be highs only reaching the lower to mid 60s - some 20 degrees lower than yesterday. A dry slot keeps the area dry and cloud free in the pre-dawn hours, but post-frontal moisture is quickly filling in from west MI with low clouds and spotty showers arriving over the next few hours. Weak daytime instability in the moist cyclonic flow allows for additional light showers at times through the day. With the surface low tracking across northern MI, a tight pressure gradient will produce gusty winds to around 30 to 35 mph that taper off this evening.

The upper low slowly peels off to New England on Sunday but leaves us beneath a lingering moist cyclonic northwest flow pattern that maintains cool and mostly cloudy conditions through the day. Far southern areas stand the best chance to see more prolonged intervals of sun, so highs there may be able to climb into the upper 60s. A shortwave emerging from the Canadian Prairie then tracks through the northern Lakes Sunday night into Monday morning, sending a backdoor cold front across the area. Northeast wind over the cool waters of Lake Huron reinforces the cool pattern through the mid-week with highs each day limited to the upper 50s and lower 60s.

A closed upper low develops over the Plains early in the week and slowly meanders toward the Ohio Valley. Confidence is increasing for this system to interact/merge with a lobe of vorticity stalled north of Lake Huron on Wednesday. This evolves into a broad, stalled low that lingers in the vicinity through the end of the week.
Instability and thunderstorm chances are likely held south of the area, but a period of wet and cool weather is becoming increasingly likely from Tuesday night into Friday.

MARINE...

Moderate west-southwest winds follow last night's frontal passage with the strongest winds (20-30kts) still expected over the southern half of the region where the gradient is strongest. Small craft advisories remain in effect for all nearshore waters through this evening. Low fully departs Sunday shifting winds to the northwest.
Gusts peak near 20kts during the day before weakening overnight as weak high pressure slides overhead. Winds gradually shift to the northeast early next week in response large low pressure moving out of the Plains towards the Ohio Valley. Strongest flow looking to occur Wednesday as the surface low moves across the Ohio River. Some showers are possible with this system but the region is too far removed from the current favored track to support much in the way of thunderstorm chances.

DTX WATCHES/WARNINGS/ADVISORIES
MI...None.
Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ421-422- 441>443.

Lake St Clair...Small Craft Advisory until 10 PM EDT this evening for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 10 PM EDT this evening for LEZ444.