850
FXUS63 KDTX 312309
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
709 PM EDT Sun Aug 31 2025

.KEY MESSAGES...

- Near normal high temperatures and dry conditions prevail through
Tuesday. Cool overnight lows continue however.

- Showers Wednesday night will give way to much cooler temperatures
late week through the weekend. Additional shower chances late week.

&&

.AVIATION...

The center of surface high pressure will slowly inch eastward away
from Southeast Michigan towards Quebec tonight and Monday. A light
easterly wind direction will be preferred with time, bringing some
prospects of moisture fluxing off the adjacent Great Lakes. Latest
surface pressure deficit guidance does suggest some potential for
radiational fog after 09Z particularly in the Thumb. Will maintain
MVFR mention of br at all taf sites, but any dense fog is expected
to be brief and very localized. A persistence forecast supports
FEW-SCT boundary layer cloud by late morning Monday.

For DTW/D21 Convection...No thunderstorms during the period.

THRESHOLD PROBABILITIES...

* None

&&

.PREV DISCUSSION...
Issued at 308 PM EDT Sun Aug 31 2025

DISCUSSION...

Surface high pressure remains centered over lower MI/central Great
Lakes today resulting in another pleasant day of mostly sunny skies
and light winds. With thermal troughing beginning to shift to the
eastern Great Lakes, highs have been able to moderate a bit closer
to normal in the mid 70s. Another clear or mostly clear night in
store as diurnal cumulus fades with the sun keeping lows on the
chiller side in the mid-upper 40s. Still some signal that very weak
easterly flow off Lake Huron could support enough moisture flux to
allow areas of fog to develop in the Thumb, particularly the eastern
portions.

Surface ridge axis shifts to our east by early Monday allowing for
continuing moderation in daily highs, further aided by mostly sunny
skies. High temps both Labor Day and Tuesday reach right around
early September average in the upper 70s to 80. However with mostly
clear overnight skies and a dry resident airmass (dewpoints in the
low 50s), cool nights (lows mid 50s to near 50) will continue.

Winds organize out southwest Wednesday as respectable mid-upper
trough swings out of the Canadian Prairie toward the far northern
Great Lakes. Low pressure rapidly deepens as the mid-level
circulation closes off resulting in strengthening winds locally
latter half of the day. Associated showers currently are favored to
reach SE MI Wednesday night-Thursday morning which will greatly
limit any embedded thunder chances. Attendant cold front then sweeps
across southern lower MI late Thursday morning-afternoon as strong
CAA follows. 850mb temps fall from 14-15C Wednesday night to 4-6C by
Thursday evening keeping afternoon highs well below average in the
lower 60s. Upper trough then settles over the Great Lakes through
the coming weekend maintaining well below average temperatures.
Periodic rain chances are expected during this timeframe as the
cooler airmass and upper divergence will be conducive for lake
effect shower development. Additionally, longer range model
solutions advertise a secondary shortwave rounding the trough Friday-
early Saturday offering better organized shower coverage.

MARINE...

Sprawling high pressure over the Great Lakes region providing light
and variable winds, which looks to continue through Tuesday with dry
conditions. There is a low chance for some fog to develop late at
night into the early morning hours due to the warm waters.  A
pattern shift mid week will be characterized by strengthening low
pressure across the northern Great Lakes resulting in the passage of
a strong cold front late Wednesday. This will drive much colder air
across the lakes for Thursday, ushered in by strong northwest winds.
The forecast for Friday is a bit in flux, as there have been varied
model solutions with the strength and location of the next low
pressure system diving southeast from Central Canada. Outgoing
forecast for Friday suggests strong southwest winds ahead of the low
before winds swing to the west-northwest for Friday evening/night.
Enough cold air in behind this system for the weekend to bring the
potential for waterspouts.

&&

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

$$

AVIATION.....CB
DISCUSSION...KDK
MARINE.......SF


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at www.weather.gov/detroit.