textproduct: Detroit/Pontiac

KEY MESSAGES

- Dry conditions with cool to seasonable temperatures Thursday and Friday; chilly Thursday night with lows in the upper 30s to lower 40s.

- Much warmer Saturday with temperatures in the upper 70s to around 80 degrees.

- Next significant chance of rain arrives for the second half of the weekend.

DTW THRESHOLD PROBABILITIES

* None

PREV DISCUSSION

Issued at 336 PM EDT Wed Oct 7 2026

DISCUSSION...

Pretty quiet forecast heading through the end of the work week as the energetic jet stream resides mostly across Canada. Stacked low centered over Hudson Bay today will send a trough down through the Great Lakes on the nose of a mid level jet streak tonight. This opens the door for broad troughing to encompass a portion of the northern Great Lakes while high pressure slides through the Midwest into the Ohio Valley building a stable airmass across the southern Great Lakes. For tonight, northwesterly cool flow over the relatively warm lakes will provide a boost to instability and though moisture is weak, PWATs roughly 0.6 inches, there could be enough concentrated moisture in the region of steeper low/mid level lapse rates to allow some scattered showers or even a thunderstorm over the north half of Lake Huron. Further south into the Thumb, moisture is even thinner and forcing weaker, but the cool airmass and low level jet could be enough to touch off some scattered showers over the Thumb this evening into tonight. Current radar over the U.P. does have thunderstorms present adding to the confidence of weak storms over northern Huron later.

High pressure then expands back northward across the region ending any rain chances Thursday into Friday. Cool air within the trough will drop 850mb temps into the single digits above 0C leading to cool highs in the 60s to end the week. Clearing skies under the ridge with the cool airmass in place could allow some low temps to fall into the upper 30s Thursday night in some of the cooler spots, otherwise low 40s could be in store for most locations.

Brief but strong warm up on Saturday as strong ridging over the Plains advances eastward over the Great Lakes. ECMWF is a touch warmer (~18C at 850mb) than GFS (-16C) Saturday with strong southwesterly flow into the region. Current forecast is for temps to touch 80F in the Saginaw Valley with upper 70s for most other locations. The warm front leading the way could touch off a few showers after 00Z Saturday with the bubble of stronger theta e lifting through the area. Though model output is not strong in producing rain, we've see these leading theta e gradients on elevated warm fronts produce narrow brief areas of showers many times. For now, we'll note it and see if we need to add POPs later.

This warmup will be brief as attention the turns to TS Isaias which is set to make landfall over MS Friday evening then getting drawn northward into the Ohio Valley before getting caught in the westerlies and forced to the east coast. This brings the rain shield into Lower MI Saturday night and/or Sunday. Details will come together in the coming days, but for now expect a gradient of rain from south to north with the highest totals over southern lower MI. Abundant moisture with a tropical system will lead to efficient rain production for any areas that get clipped by the rain shield.

MARINE...

Moderate southwesterly winds gradually weaken this evening as a cold front extending from low pressure near James Bay crosses the central Great Lakes. The lighter gradient winds also veer west-northwesterly behind the front early tonight. However, an uptick in speeds returns late tonight or early Wednesday as the upper level jet deepens over the region. Stability trends lower with the slightly cooler airmass, and given the rejuvenated low-level jet winds, mixing likely delivers some elevated gusts. Potential exists for gusts to around 30 knots over portions of Lake Huron Thursday afternoon, with marginal gusts to gales possible for northern Huron. A Small Craft Advisory may be needed over The Thumb should confidence rise in the frequency of 25+ knot gusts, but any higher end gusts further north should be infrequent enough to preclude a Gale Warning. Mid/Upper Mississippi Valley high pressure then expands into the area Thursday night and Friday offering weaker winds with a southerly shift.

DTX WATCHES/WARNINGS/ADVISORIES

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