Expert Forecast Opinion

778
FXUS63 KDTX 210712
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
312 AM EDT Wed Oct 21 2026

.KEY MESSAGES...

- Areas of fog tonight.

- Mild and dry through the week.

&&

.DISCUSSION...

The combination of clear skies under light east to southeasterly
flow has resulted in the proliferation of dense fog through southern
and central Michigan, and to a lesser extent across the Thumb. The
favorable flow has brought about better moisture advection derived
from Lake Erie inland, where continued advection along with gentle
upsloping will see dense fog expand west and northwest through
central MI. This will continue to promote fog across Monroe and
Lenawee counties, where a dense fog advisory is in effect until 10
AM EDT. Portions of western Washtenaw, the Tri-Cities and Thumb will
likely see periodic fog, possibly dense at times, through daybreak,
with sunshine then works the lift and scour out fog through the
remaining morning hours.

The familiar persistence forecast will again take hold today as high
pressure sits over the Great Lakes, which will be reinforced through
Friday as a longwave ridge expands through the Plains and
Midwest/Great Lakes. Dry weather and above normal temperatures
continue as a result through the weekend. Daytime highs will return
into the upper 60s today and tomorrow and may make a push into the
70s by tomorrow afternoon. A very subtle decrease in highs (low to
mid 60s) will be likely Friday with northeast flow coming off the
lake, but as the aforementioned high pressure system starts to
depart into the western Atlantic, low-level flow re-orients south to
southwesterly, resulting in the gentle uptick in waa pushing highs
back in the mid to upper 60s. Fog, dense at times, remains highly
sensitive to wind direction as shallow lake moisture advection has
been the main driver of recent events. Tomorrow morning fog is a
possibility under clear skies, but the unfavorable flow lowers
confidence relative to today. Friday morning will be much more
conducive to advective fog given the light east to northeast flow
off of Lake Huron and Saginaw Bay. Patchy to areas of dense fog will
be possible through the Tri-Cities and Thumb with lowered confidence
for the degree of expansion inland. Outside of morning fog concerns,
dry and sunny weather continues through the weekend.

&&

.MARINE...

High pressure remains over the region through the end of the week
resulting in benign marine conditions. The current high now centered
over Quebec, will slowly shifts east through tonight with a dry cold
front then passing southward early Thursday. This front will quickly
be followed by another area of high pressure that will then hold
through most of the weekend. Wind gusts will stay below 20 knots
through the end of the week. Winds will be southerly today before
flipping around to the north for Thursday behind the cold front
early in the morning.

&&

.PREV DISCUSSION...
Issued at 1154 PM EDT Tue Oct 20 2026

AVIATION...

Conditions will become favorable for some degree of fog and/or very
low stratus development late tonight. Forecast will continue to
highlight a window for MVFR to IFR visibility restrictions with an
entry level mention for very low stratus. There remains potential
for one or more southeast Michigan terminals to witness a period of
LIFR in fog/stratus, although confidence in occurrence remains too
low to include attm. Any lingering fog/stratus will lift thru late
morning, affording another period of clear skies with light wind for
the remainder of the daylight period.

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

DTW THRESHOLD PROBABILITIES...

* Low for cigs/vsby to fall below 200ft and/or 1/2SM late tonight.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Dense Fog Advisory until 10 AM EDT this morning for MIZ082-083.

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

$$

DISCUSSION...AM
MARINE.......DRK
AVIATION.....MR


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