Marine Weather and Tide Forecast for Harrisville, MI

SHORT TERM /THROUGH MONDAY/
Issued at 325 PM EDT Sun May 11 2025

Pattern/synopsis: Surface high pressure will move east away from Lake Huron, though a ridge will extend west into lower MI. This ridge stretches into southern lower MI tonight, before migrating north on Monday. Aloft, a w-e oriented 500mb ridge axis starts in the southern lakes, then pushes north into our neck of the woods.

Forecast: Quiet, excepting fire wx concerns. Ongoing clouds over far eastern upper MI will gradually get displaced eastward.
Late on Monday, mid and high clouds will push northward into southern parts of our area. Otherwise, little cloud cover in the short term period, with increasing ridging surface and aloft.
Winds will decouple tonight, but not as emphatically as last night; there is an increasing wind field off the surface, especially in the north half of the forecast area. Between that and a warmer start, temps will not drop nearly as far as last night. Lows will be mainly in the 40s.

Winds available to mix down will decrease on Monday, as the surface ridge axis drifts north, and the pressure gradient relaxes with time. Expect to mix down 20 mph wind gusts in the afternoon in the interior of northern lower MI. Warmest day of the year thus far; highs mid-upper 70s in eastern upper, low- mid 80s in the interior of northern lower MI. NBM10Pct guidance is still appropriate for dew point progs, which mixes out min RH values deep into the teens (plenty of mid teens in the interior). Don't have enough winds to result in high-end fire wx concerns, but dry fuels, low RHs, and an incomplete spring green-up will definitely keep some concerns going.

LONG TERM /MONDAY NIGHT THROUGH SUNDAY/
Issued at 325 PM EDT Sun May 11 2025

Midlevel pattern remains the same at longwave ridging over the southern Canadian Providences continues warm and dry conditions until troughing from the pushes returns atmospheric moisture to the northwoods. This weak wave of energy will move a cut-off surface level low to the midwest and return showers as soon as Tuesday to northmen Michigan. Rounds of showers and storms will linger through the remainder of the week as this trough stalls and becomes more disheveled and falls apart. Another trough currently over the Pacific Northwest will finally push this sytem to the northeast at the end of the week, finally ending this drearier pattern for the Great Lakes region and returning widespread subsidence around the late Saturday/Sunday timeframe.

Even with an incoming pattern chance to the region compared to current "high and dry" weather, not a lot of impactful weather is expected for most of the week. Only a few isolated showers are in the forecast this Tuesday, especially across mid Michigan as the southern parts of the CWA will see a few convectively driven showers generating maybe a tenth or so of QPF. Otherwise most areas will remain mostly cloudy south of M-32 and mostly sunny north of the Bridge. This pattern of on and off scattered shower accompanied by thunder will continue through midweek as this system lingers across the region. Best chance of heavier showers and some stronger storms will be Thursday night as a cold front attached to the Pacific NW trough drags across the CWA Most recent guidance is hinting at the potential of one or two severe storms Thursday night as dew points spike into the 60s with moderate amounts of instability. Frontal timing appears to be overnight which is not ideal, but moderate lapse rate and enough CAPE should support severe level amounts of hail or even strong downdraft winds. Some showers may linger into the weekend but subsidence returns to the region this Sunday, thus returning a drier pattern by then end of the week/early next week.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
Issued at 735 PM EDT Sun May 11 2025

VFR expected through the period with generally SKC (some clouds approaching from the south Monday afternoon). Dry conditions and LLWS tonight for the northern TAF sites. Winds south to southwest tomorrow AOB 10KTs, some gusts in the teens possible.

APX WATCHES/WARNINGS/ADVISORIES
MI...None.
MARINE...Small Craft Advisory until 11 PM EDT this evening for LSZ321.