textproduct: Detroit/Pontiac

KEY MESSAGES

- Dry weather continues through early next week with temperatures slightly above normal, despite a weak and dry cold front sagging southward across the region tonight into Monday.

- Potential for fog tonight mainly southern areas, with a better opportunity for patchy fog or low clouds developing across the Thumb and Tri-Cities region Monday night.

- The next appreciable chance for measurable rainfall holds off until Thursday, mainly for areas across the northern half of Southeast Michigan.

DISCUSSION

A strong upper-level ridge over the western Gulf Coast states will be slow to break down over the next several days as it drifts east. The southern Great Lakes will reside on the northern fringe of this ridge. A weak and dry cold front looks to sink south tonight into Monday as expansive high pressure (1034 mb) builds over northern Ontario. Not much cooler air will reach the southern Michigan border, as 850 mb temps hold in the upper single digits to near 10 C early next week.

Cooler air and light easterly flow will infiltrate the northern half of the CWA, which could be conducive for fog or low cloud development over the Thumb and Tri-Cities regions Monday night. For tonight, potential fog development looks to be confined to the southern half of the CWA. However, with light southwest flow ahead of the cold front, prospects appear much lower compared to the past couple of days without the marine influence in play.

Today marks the 9th consecutive dry day in a row, and it continues to look like we will be hard pressed to generate measurable rainfall. The best chance over the next 5 days looks to be on Thursday, as Euro ensembles indicate chances increasing to at or above 50 percent for a hundredth of an inch across the northern half of the CWA. With the upper-level wave and jet energy just beginning to track into the Gulf of Alaska at the present time, sticking with the lower-chance PoPs of the NBM is reasonable.

MARINE

A moisture-starved cold front is approaching Lake Huron this afternoon. Latest radar data shows a few scattered light showers along a trough axis over central Huron, well ahead of the boundary. Broader coverage of showers exists along the boundary, near The Straits. The front will take the course of the night to advance across the central waterways, featuring decreasing chances for additional rainfall. Post-frontal northerly flow ensues resulting in rising winds and waves. Depending on when flow turns more northeasterly, there could be a brief period of max waves heights above 5 feet for portions of Saginaw Bay and southern Lake Huron where fetch is maximized. Therefore, a short-fused Small Craft Advisory may be needed Monday evening. High pressure then translates southeastward across Ontario on Tuesday, before settling over New England by Wednesday. Winds will slowly veer easterly during this time. Several additional waves of low pressure are expected to track northeastward from The Plains through the Upper Midwest during the the mid-late week time-fram, with winds and waves largely holding below headline criteria.

PREV DISCUSSION

Issued at 138 PM EDT Sun Oct 25 2026

AVIATION...

Surface high pressure will slowly edge out of the forecast area as a zonal upper level jet axis progressively builds southward over the northern Great Lakes. A weak frontal boundary within a corridor of broader deformation will push due southward tonight clearing through Southeast Michigan by 18z Monday. Forecast data has been very consistent in showing strong anticyclonic curvature to flow trajectories through the lower level front thus limiting synoptic scale ascent. Pooled moisture in advance of the front leads to a fog potential tonight despite more potential for higher clouds to dissuade near surface saturation. Will err with the NAM that cloud will be transparent enough and prefer a persistence forecast (LIFR) at the lower elevation Detroit terminals at daybreak.

D21/DTW Convection... Thunderstorms are not forecast through the TAF period.

DTW THRESHOLD PROBABILITIES...

* Moderate for cigs/vsby below 200 ft and/or 1/2SM this morning.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None.