Expert Forecast Opinion

023
FXUS63 KDTX 210344
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1144 PM EDT Wed Aug 20 2025

.KEY MESSAGES...

- Seasonable temperatures and dry weather expected today through
Friday.

- Rain chances return this weekend as low pressure drags a cold
front through the area.

&&

.AVIATION...

The 00Z DTX sounding showed a couple deep inversions in the low
levels. While there has been fluctuations in cloud coverage and
ceiling heights during the late evening, the low level flow will
veer more easterly through early Thurs morning. Given the extent of
low clouds to the east, this is expected to result in a re-expansion
of clouds across Se Mi during the course of the early morning hours.
Model soundings and upstream trends suggest continued fluctuations
between VFR and MVFR ceiling heights. A more notable push of
subsidence/dry air will offer higher probabilities for clearing mid
to late afternoon on Thursday.

For DTW/D21 Convection... No thunderstorms through the TAF period.

THRESHOLD PROBABILITIES...

* High in ceilings aob 5000 feet tonight. Moderate on Thursday.

&&

.PREV DISCUSSION...
Issued at 300 PM EDT Wed Aug 20 2025

DISCUSSION...

Active subsidence with strong static stability between 4.0 and 10.0
kft agl is in place across Southeast Michigan this afternoon.
Differential cold advection in the low levels combined with moist
flow off of the lakes has led to trapped moisture under the base of
the midlevel inversion. Latest model data lends some support for a
continuation of clouds tonight. May observe some thinning during the
evening hours with loss of daytime heating, but preference was to
lean into stratus/stratocu tonight. Did increase the sky cover grids.

Deep mid-upper level ridge will then build across the Great Lakes
for the end of the week. Strong signal in anticyclone building
overhead late Thursday and Friday. Pleasant late August weather with
dry conditions, high temperatures around 80 degrees and dewpoints
the 60s.

Strong model consensus in a deep, large area of upper level low
pressure digging into and then stalling over the Great Lakes region
Saturday through Tuesday of next week. Main prefrontal trough/cold
front feature look to pass through Saturday afternoon/Saturday night
bringing the best chance of showers and thunderstorms. Diurnal,
spotty afternoon shower and thunderstorm chances will be possible
each of the afternoons Sunday-Tuesday. Difficult to get too excited
as model data usually over resolves the coverage or broadbrushes PoP
chances. Highs Sunday - Tuesday are expected to be in the lower 70s
some 8 to 10 degrees below normal.

MARINE...

Northeasterly winds begin to weaken this evening, continuing through
the night, as high pressure expands across the central Great Lakes.
Said high drifts over the region through Friday maintaining
generally lighter winds (aob 15kts) and dry conditions. Large low
pressure system tracking over northern Ontario drags a cold front
across the region late Friday night-Saturday bringing the next
chances for showers and thunderstorms. An upper trough then is
expected to settle over the Great Lakes for the rest of the weekend
into early next week allowing a much cooler, fall-like airmass to
sink south. Strengthening cold advection with this airmass brings
breezy conditions as west/northwest winds reach 15-25kts. Some
periods where gusts approach or exceed 30kts are likely as well.
Cooler weather also brings lake effect shower and waterspout chances
through that timeframe.

&&

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

$$

AVIATION.....SC
DISCUSSION...CB
MARINE.......KDK


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