895
FXUS63 KDTX 011657
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1257 PM EDT Mon Sep 1 2025

.KEY MESSAGES...

- Dry with seasonal temperatures into Wednesday.

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

&&

.AVIATION...

Resident high pressure supplies another day of ideal aviation
conditions while holding in place from the upper Midwest across the
Great Lakes. A near repeat performance of Sunday is in progress as
VFR consists of shallow cumulus expanding to generous scattered or
briefly broken coverage with light east wind. These clouds dissipate
with sunset this evening followed by another round of clear sky over
Lower Mi late tonight into Tuesday morning. High pressure is in a
better position to maintain light easterly wind across Lake Huron
and Erie for a weak marine influence on surface/boundary layer
moisture. Wind speed has lower predictability due to a weak pressure
gradient at night, so the forecast will carry a few hours of MVFR
fog restriction while monitoring trends for lower thresholds into
Tuesday morning.

For DTW/D21 Convection...No thunderstorms today through Tuesday.

THRESHOLD PROBABILITIES...

* None

&&

.PREV DISCUSSION...
Issued at 303 AM EDT Mon Sep 1 2025

DISCUSSION...

Weak mid level low pressure over the Mid Atlantic will lift across
the eastern Great Lakes tonight into Tuesday. This system will not
be able to dislodge the mid level ridge axis over Lower Mi or make
much impact on the expansive sfc high pressure that stretches across
the eastern and southern Lakes region. Deep columnar subsidence will
therefore persist today and Tuesday and will remain supportive of
dry conditions. While light easterly winds will persist at the
surface today, model soundings show mixing depths that are a bit
higher than yesterday by at least 1500 feet. This will support a
little warmer afternoon highs; upper 70s to around 80. The low level
flow will will veer more southerly on Tuesday, driving slightly
warmer air into Se Mi and warranting highs around 80. The overall
dry ambient airmass, light winds and clear skies will still promote
optimal radiational cooling conditions, allowing nighttime mins to
drop back into the 50s.

The 00Z model suite remain consistent in showcasing a potent short
wave dropping into nrn Minnesota from northern Canada on Wednesday,
transitioning to a deep closed mid level low which meanders across
nrn Ontario into the weekend. Southwest flow will increase across
srn Mi on Wednesday as this wave and associated cold front advance
into the northern and western Great Lakes. Although there are some
model indications of prefrontal troughing over Se Mi Wednesday
afternoon, mid level capping and weak forcing will inhibit
convective initiation ahead of the main cold front. 15 to 20 knots
of flow within the deep daytime mixed layer will push Wed highs into
the low 80s. Strong mid level positive PV advection along a deep
layer theta e axis will then bring widespread showers along/behind
the cold front associated with the aforementioned upper low. Model
solutions and probabilistic guidance generally suggests a 5 to 7 hour
window of strong ascent. Timing uncertainty at this stage will
spread forecast pops out from Wednesday afternoon through early
Thursday morning. The strength of the ascent may compensate to a
degree for weak instability, thus support a chance for thunderstorms.

The airmass in the wake of the front will be quite cool for early
September as 850mb temps drop into the single digits. This will
result in temperatures being a solid 10 to 20 degrees below normal
late week into next weekend. Cool air aloft combined with potential
short wave impulses will support additional chances for showers,
especially on Friday.

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.....BT
DISCUSSION...SC
MARINE.......SF


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