059
FXUS63 KDTX 072307
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
707 PM EDT Tue Oct 7 2025

.KEY MESSAGES...

- Lingering showers over the southernmost areas taper off early this
  evening.

- Cool and dry conditions last through the end of the week.

- Frost is possible Wednesday night and Thursday night.

&&

.AVIATION...

A cooler and drier environment will expand across the region tonight
within a post-frontal northerly gradient. Any lingering low cloud
across the Detroit airspace vacates late this evening, leaving
simply some pockets of mid level cloud for the overnight period.
High pressure anchored to the north will maintain control Wednesday
and Wednesday night. Modest moisture flux off lake Huron in ongoing
northerly flow will attempt to counter the existing dry airmass,
affording a scattered to perhaps briefly broken coverage of VFR
diurnal cu during the afternoon. Northerly winds peaking near 10
knots Wednesday.

For DTW/D21 Convection...Thunderstorms are not expected through the
forecast period.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling 5000 ft or less Wednesday afternoon.

&&

.PREV DISCUSSION...
Issued at 310 PM EDT Tue Oct 7 2025

DISCUSSION...

Surface cold front is beginning to push south and east of the area
this afternoon with elevated portions of the frontal slope still
lingering south of a Port Huron-Howell line. This supports lingering
scattered light showers/drizzle through the first half of the
evening before the slope fully vacates SE MI. In its wake, strong
high pressure dropping out of northern Canada expands across the
Midwest and Great Lakes. Northerly low level flow along the eastern
flank of the high combined with upper troughing sliding over the
central Great Lakes sets up respectable CAA with local 850mb temps
falling to around 0C (plus or minus a degree) for Wednesday.
Resultant highs only top out in the mid 50s to lower 60s- coolest in
the Thumb, falling short of the mid 60s early October averages.
Cooler airmass will be supportive of moisture flux off Lake Huron
however forecast soundings still suggest only a shallow saturated
layer below the subsidence inversion capping convective depths at
only a few thousand feet, which likely allows stratocu development
over the eastern half of the CWA but should preclude any light
rain/drizzle.

Favorable radiative cooling setup develops overnight Wednesday as
the high center drifts over the lower peninsula promoting clearer
skies and light, if any, winds. With surface dewpoints ranging
between 32-34F, low temps will fall into the mid to lower 30s
(outside of Detroit/immediate lakeshore areas) offering the season`s
first frost chances. Surface ridge axis shifts to the eastern Great
Lakes by Thursday re-establsihing southwest lower level flow and
gradual WAA through the rest of the week. That said, some areas of
frost are possible again overnight Thursday, particularly in the
Thumb, due to another clear, calm night under departing thermal
troughing.

MARINE...

Post frontal cold air advection brings an uptick in northwest winds
across the area through the afternoon into tonight. Gusts generally
peak around 25 kt over Lake Huron, though some gusts to 30 kt will
be possible across the northern part of the lake this evening. A
Small Craft Advisory remains in effect for the Lake Huron nearshore
waters starting tonight as waves build across the southern basin.
Wind direction veers to north-northeast on Wednesday as a secondary
cold front moves through, maintaining wind speeds in the 10 to 20 kt
range and producing onshore wave activity through the day. High
pressure builds directly into the area Wednesday night and offers
lighter winds and waves through Thursday. Modest southwest wind then
emerges on Friday ahead of the next cold front arriving into the
western Great Lakes.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory from 10 PM this evening to 10 PM EDT Wednesday
     for LHZ421-441>443.

     Small Craft Advisory from 10 PM this evening to 10 AM EDT Wednesday
     for LHZ422.

Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

AVIATION.....MR
DISCUSSION...KDK
MARINE.......TF


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at www.weather.gov/detroit.