215
FXUS63 KDTX 252340
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
740 PM EDT Fri Sep 25 2026

.KEY MESSAGES...

- Dry and pleasant weekend.

- Next rain opportunity midweek.

&&

.AVIATION...

Axis of midlevel moisture tracking into the area from the northwest
will cutoff over Southeast Michigan tonight as it becomes influenced
by the strong Nor`easter off the Atlantic coast. VFR midlevel
altostratus-altocumulus ceilings are expected to hold on longer into
the overnight. Calm winds brings the potential for fog late tonight
as longer nighttime period yields a stronger near surface inversion.
MOS guidance is not nearly as bullish and low confidence exists
particularly within the urban heat island of the Detroit terminals.
Daytime mixing with a very dry air mass below 6.0 kft agl is
expected to bring VFR conditions with low sky fraction Saturday
afternoon.

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

.DTW THRESHOLD PROBABILITIES...

* Low in ceilings aob 5000 feet through the TAF period.

&&

.PREV DISCUSSION...
Issued at 245 PM EDT Fri Sep 25 2026

DISCUSSION...

An extremely dry airmass is in place over southeast Michigan today,
as the 12z DTX sounding indicated a dew pt depression of 49 C at 850
MB, 47 C at 700 MB, and a PW value of 0.21 inches. The PW value
appears to set a new daily record low based on the SPC climatology
page. With this dry air and an upper level ridge expected to hold
over the northern Great Lakes this weekend, it comes as no surprise
that dry weather remains in store. Expect mild days and cool nights
this weekend into early next week. Shallow ground fog is not out of
the question with the longer nights, but uncertain if the
surface/near surface moisture is sufficient. Nam surface
condensation pressure deficits stay mainly above 5 MB.

A slow evolving upper level pattern will feature deep, stacked lows
near the Mid-Atlantic coastline into early week. So although heights
lower modestly Monday/Tuesday over the central Great Lakes, the
ridge axis remains mostly entrenched.

The next chance of rain arrives on Wednesday as a shortwave trough
tracks through. Medium range models then significantly diverge, as
the strength and interaction between the upper level low/trough over
central Canada and the closed low coming out of the Four Corners
region needs to be sorted out.

MARINE...

The expansion of a strong Canadian high pressure system from Quebec
and Ontario into the Great Lakes will provide an extended period of
light winds and dry weather through early next week. Some periodic
wind gust potential around 20 knots will be possible across southern
Lake Huron this weekend, but otherwise, wind gust potential at or
below 15 knots is expected. Wind direction will mainly hold from the
north to northeast as high pressure fills in across Michigan.

&&

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

$$

AVIATION.....CB
DISCUSSION...SF
MARINE.......AM


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