textproduct: Detroit/Pontiac

KEY MESSAGES

- Much cooler temperatures will prevail for the rest of the work week.

- Rain chances today and tonight will be greatest across Metro Detroit and points south.

DTW THRESHOLD PROBABILITIES

* Low for thunderstorms from 18Z-02Z today/tonight.

* Medium for ceiling at or below 5000 feet today, then low tonight.

PREV DISCUSSION

Issued at 300 AM EDT Tue May 5 2026

DISCUSSION...

Mid level height falls across the northern Great Lakes this morning resulting from short wave energy pivoting around the northern Ontario upper low will drive a surface cold front across Se Mi. While somewhat ill-defined due to overnight convection and a weak surface low which developed off the thumb region, the main surface front will be east of the forecast area by early afternoon. Some residual boundary layer convergence, elevated frontal forcing and a weak short wave lifting into the area from Iowa will sustain a chance of lingering showers during the day. Shallow post frontal cold air advection will drop temperatures into the 50s. The earlier fropa across the Saginaw Valley and expectation for a thinner afternoon cloud deck in this area will offer the potential for daytime heating to boost late afternoon highs back around 60 in the north.

The 00Z model suite and their respective ensembles continue to show variance as to the strength and position of a mid level short wave impulse and corresponding enhancement in elevated frontogenesis across Se Mi late this afternoon into early Wed morning. The main impact this will have on the forecast is how far into Se Mi a secondary wave of rain expands on the cool side of the low level baroclinic zone that will be draped across the eastern Great Lakes. The ongoing upscale growth of the convective complex across central Illinois and Indiana has not been handled well by much of the 00Z model suite. Those hi res solutions which have a better handle on this convection indicate a more easterly track to the forcing later today , which would limit the better rain chances to along and southeast of a downtown Detroit to Adrian line. Cloud cover and a lingering gradient flow will hold nighttime mins mainly in the 40s, with some 30s possible north of the I-69 corridor where some intervals of clearing are possible.

A secondary push of cold air is forecast on Wednesday as long wave troughing extends into the northern and western Great Lakes. While drier air will advect into the boundary layer, model soundings indicate enough moisture with the cold air aloft present to result in an expanding diurnal cu field. Cloud depth may enough to support a few sprinkles or light showers by late afternoon. Despite the seasonally cold air aloft, steep daytime lapse rates and mixing depths projected to reach 8k feet will support forecast highs in the upper 50s to around 60, with cooler readings in the thumb and Port Huron do to onshore winds. The persistence of the Hudson Bay upper low and long wave troughing over the Great Lakes will sustain seasonally cool conditions into the weekend. Numerous short wave impulses rotating across the region within the base of the longer wavelength trough will support periodic chances for showers during the latter half of the forecast period (Friday thru Monday).

MARINE...

A cold front will work across the Great Lakes this morning which will briefly reorient winds north-northwest in the wake of the front. Winds to lessen in speed and become more variable during the day today. Tonight through Thursday, winds will back from the northeast to north and eventually from the west, as another area of low pressure organizes south of the region and moves over the Continental Northeast.

DTX WATCHES/WARNINGS/ADVISORIES

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