632
FXUS63 KDTX 041824
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
224 PM EDT Fri Sep 4 2026

.KEY MESSAGES...

- There remains a chance of showers and thunderstorms through
tonight. While widespread severe weather is not expected, an
isolated stronger storm will be possible.

- More seasonable temperatures and lower humidity are slated to
return this weekend.

&&

.DISCUSSION...

Ongoing elevated convective activity fixated along a lingering
baroclinic zone and within the background of continued sufficient
mid level instability will settle to the south over the next couple
hours. Lack of meaningful daytime heating within the immediate wake
of the earlier activity offering a more notable reduction in
available instability moving forward. This occurs within an
environment seemingly lacking in greater tangible forced ascent as
more pronounced shortwave energy embedded within the mean mid level
northwest flow traverses south and west the area. Little evidence
within short range model guidance to suggest additional larger scale
redevelopment will occur at least through the back half of the peak
heating cycle. A more localized response remains plausible,
particularly near the Ohio border, given closer proximity to the
deeper instability reservoir. It would be within this environment
that s secondary, isolated opportunity remains for more organized
cells to emerge locally or track in from southern WI late this
evening into early tonight /22z-04z/ across that corridor. Forecast
maintains a lower end chance mention most locations through the
night, accounting for the presence of some elevated instability
/highest with westward extent/ and sufficiently moist boundary layer
conditions to support an early morning flare-up of showers.

The surface frontal zone sags south of the Michigan/Ohio border
through Saturday morning. Isentropic upglide and lingering low-level
convergence along the stalling frontal boundary will keep a low-end
chance for scattered showers or an isolated rumble of thunder
focused primarily across the southern tier of counties (M-59
southward to the Ohio border) early Saturday. Otherwise,
significantly less supportive airmass as available instability lacks
as surface dew points scour out into the upper 50s to lower 60s.
Expect decreasing cloud cover from north to south through the
afternoon as surface high pressure expands over the upper Great
Lakes. Onshore lake-breeze components off Lake Huron will keep
eastern and coastal areas cooler. High temperatures more comfortably
top out in the mid-to-upper 70s Saturday. High confidence then
exists in dry and benign conditions holding through the remainder of
the weekend as expansive high pressure centers directly over Lower
Michigan. The deep layer stability held with this environment
ensures limited cloud production, while temperatures hover near-
normal for early September.

Low to mid level ridging will continue to mark conditions during the
early week period. Associated deep layer stability with a very dry
profile ensures benign weather, with the incremental increase in the
mid level height field netting a very modest warming trend but with
temps still seasonable. Low-level return flow around the backside of
the departing surface high pushes 850 mb temperatures back into the
+16 to +18C range by Wednesday afternoon. An associated increase in
low level moisture quality likely to commence at the same time ahead
of an inbound cold front tied to a northern stream shortwave moving
across Ontario. This will bring the next chance for meaningful
rainfall, followed by a more notable cooling trend directed for the
end of next week.

&&

.MARINE...

Greatest thunderstorm potential will generally remain south of the
waterways through tonight, although an isolated storm cannot be
ruled out. Otherwise, high pressure anchored over Ontario will
increase influence heading into the weekend. This will bring drier
and more stable conditions. Prevailing wind from the northeast may
bring a modest increase in wave action along portions of the lake
Huron nearshore waters, but are expected to remain below advisory
levels at this time.

&&

.PREV DISCUSSION...
Issued at 151 PM EDT Fri Sep 4 2026

AVIATION...

The frontal boundary and associated instability responsible for
convection yesterday/this morning have started to settle south
toward the Ohio border. This pushes the main corridor of
thunderstorms chances south of the terminals through the afternoon-
evening, with just a low chance for redevelopment in the local
airspace. As the front drops south, moisture pooling and weak
gradient flow will afford another opportunity for low stratus/fog
development overnight. Daytime mixing attempts to scatter this out
Saturday afternoon, although the NE flow component off the lake
could cause stratus to linger in some spots.

D21/DTW Convection... the main instability pool has shifted south of
DTW/D21 leaving just a low chance for thunderstorm redevelopment
this afternoon-evening.

DTW THRESHOLD PROBABILITIES...

* High for ceiling 5000 ft or less tonight and Saturday morning.

* Low for thunderstorms this afternoon and evening.


&&

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

$$

DISCUSSION...MR
MARINE.......MR
AVIATION.....MV

You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.