Marine Weather and Tide Forecast for Grosse Pointe Farms, MI

DISCUSSION

1020 mb surface high is located over northern MI this morning with its southern flank maintaining light east flow across all of Lower Michigan. Sharp transition from clear to overcast skies noted along a line from Ann Arbor-Detroit marks the 850-700mb deformation axis where southern stream moisture transport clashes with the dry Canadian airmass to the north. Expectation is for this moisture to shear out through the day as the Ohio Valley wave drifts east, but will maintain at least some sky cover across SE Michigan with diurnal cu development expected again this afternoon. Final day of cooler temperatures with highs right around 80 degrees ahead of the anomalous ridge that begins to build Sunday.

Mid level height rises really begin to ramp up Sunday afternoon as an upper low settles into the Intermountain West. High temperatures Sunday reflect the start of the warming trend, breaking into the low-mid 80s which has only happened a handful of times over the past two weeks. Diffuse low level wind field organizes out of the southwest, kicking off a period of strong warm advection Sunday night that continues through the first half of the work week. Moisture that has been pooling over the Ohio Valley and Mid-Mississippi Valley regions gets recycled northeast toward the Great Lakes in the process, triggering low shower/storm chances Monday with the arrival of the higher theta-e airmass and a weak perturbation rounding the ridge. Widespread convection through the first half of the week will then be strongly limited by lower tropospheric subsidence (850- 600mb layer) and increasing LCL heights. This will be a direct result of the strong ~594-597 dam ridge that builds across eastern CONUS Sunday-Monday, keeping the bulk of synoptic waves/nocturnal low level jet enhancement well to our west. That being said, cannot completely discount the role of mesoscale features in this type of pattern which could lead to a more localized convective response, just with low predictability this far out.

Main story of the forecast is the extreme heat potential, which will span most of next week. Heat and humidity arrive Monday with temperatures climbing into the 90s and dewpoints in the low 70s. This brings the heat index near to possibly above 100 degrees. One caveat Monday is the low PoP/cloud potential, but this becomes less of a concern by mid-week as the column becomes drier and more stable. Max mid-level heights expected overhead Tuesday-Thursday, which will be the hottest days where highs of 100 degrees are in play. Over half of EPS/CMCE members forecast high temperatures Wednesday and Thursday of 100+ degrees at DTW. The last time any of the three climate sites (Detroit, Flint, Saginaw) broke into the 100s was in 2012, for reference. Prolonged stretch of heat indices well above 100 degrees certainly exceeds entry level heat headlines, and ventures into extreme heat territory. Impacts will be exacerbated by lack of cooling overnight as lows only drop into the mid 70s.

Some relief from the heat looks to arrive Friday into the holiday weekend as the ridge begins to flatten/weaken slightly, but with highs still above normal. Break down in the height field will also open up SE Michigan for easier erosion of the cap and more convective activity late week.

MARINE

High pressure will hold over the region through the weekend resulting in light northeasterly winds under 10 knots through Sunday. A warm front will lift north through the region on Monday opening the door for very warm air to move into the region for next week. There will also be a chance of showers and thunderstorms for northern Lake Huron Monday as the front lifts north. Winds will turn southeasterly on Monday with gusts increasing to around 20 knots.

PREV DISCUSSION
Issued at 120 AM EDT Sat Jun 27 2026

AVIATION...

A stalled frontal boundary over the Ohio Valley maintains SCT/BKN mid-cloud (>9kft) through the rest of the night around the Detroit terminals with cloud in the north generally confined to cirrus.
Patchy fog/mist remains possible late tonight near mbS as light winds off the Saginaw Bay provide just enough near surface moisture.
Otherwise, VFR conditions and 10kt or less NE wind in place for Saturday as the region is governed by high pressure over the northern Great Lakes.

D21/DTW Convection... No thunderstorms forecast through Saturday.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling at or below 5000 ft tonight.



DTX WATCHES/WARNINGS/ADVISORIES
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.