931
FXUS63 KDTX 230403
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1203 AM EDT Thu Jul 23 2026

.KEY MESSAGES...

- Dry conditions with below normal temperatures expected through the
  rest of the week.

- Next chance for showers/storms arrives late Saturday night into
  Sunday while temperatures climb into the mid-upper 80s.

&&

.AVIATION...

Ideal VFR aviation weather is provided by a broad area of Midwest
high pressure as it builds into southern Lower Mi and the Ohio
valley late tonight and Thursday. After clear sky and light wind
during the night, a fair weather cumulus field returns in the
afternoon but with less coverage compared to Wednesday. These clouds
dissipate in favor of clear sky again Thursday night.

D21/DTW Convection...No thunderstorms forecast.

.DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 354 PM EDT Wed Jul 22 2026

DISCUSSION...

Dissipating right jet exit region over southern Lower Michigan is
still facilitating upper level convergence, leading to a weak
subsidence tendency. This occurs as longwave troughing remains
entrenched across most of the Great Lakes region for the next 24
hours, with a VortMax sweeping across northeast Lower and northern
Lake Huron. Forecast soundings indicate a seasonably dry column with
the 22.18Z KDTX RAOB measuring a PWAT near 0.55 inches, below the
climatological 10th percentile. Diurnal cumulus positioned just
below a 5 kft inversion layer wanes this evening, after the boundary
layer decouples. Expect mostly clear skies overnight as surface high
pressure builds southeastward. Winds trend toward calm after
midnight as the gradient relaxes.

The surface ridge centers over Chicago on Thursday with the longwave
axis departing east. This results in mid level flow turning zonal
amidst geopotential height rises. 850 mb temperatures are forecast
to moderate, given the anticyclonic orientation to the lower column
flow. Warm advection setup lifts values to around 11C by Thursday
afternoon, marking a steady warming trend that should progress
through the weekend. Favorable insolation conditions arise given a
low cloud fraction and weak winds, lifting highs into the upper 70s.

The current stretch of dry weather persists Friday as the center of
the anticyclone drifts east, settling over the Ohio Valley. This
causes surface flow to back toward the south-southeast, initiating
the gradual rise in dewpoints over the weekend. Winds aloft begin to
strengthen Friday night and into Saturday as the synoptic pattern
becomes more active. A large ridge over the western half of CONUS
amplifies with stronger embedded flow rounding the apex. This
interfaces with a deep upper low over Hudson Bay. Expect the
resident dry air to delay saturation until late Saturday or early
Sunday, ahead of an ejecting ridge-running shortwave targeting
Southeast Michigan. Showers and storms are possible with this wave
as moisture/instability increase. Sunday or Monday appears to be the
warmest day of the forecast period, with highs briefly breaking
above normal, into the upper 80s.

MARINE...

Northwest winds peaked late this afternoon in the 20 to 30 knot
range as low-level cold advection has largely exhausted itself.
However, elevated waves over the southern Lake Huron basin will take
time to subside below 4 feet; Small Craft Advisories remain in
effect into the evening hours.

850 MB temperatures, currently at or slightly below 7 C, will
gradually warm over the next couple of days, reaching around 12 C on
Friday. With the center of the surface ridge over the southern Great
Lakes Thursday into Friday, the lightest winds will be over Lake St.
Clair and Lake Erie. Even over Lake Huron, wind speeds should remain
predominately under 20 knots. A surface trough slowly passing
through during the weekend will bring a good chance of showers and
isolated thunderstorms, though winds are expected to remain light.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.

&&

$$

AVIATION.....BT
DISCUSSION...KGK
MARINE.......SF


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