420
FXUS63 KDTX 220858
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
358 AM EST Sat Nov 22 2025

.KEY MESSAGES...

- Mainly dry conditions this weekend aside from a slight chance for a
  shower in the Thumb region late tonight.

- Breezy conditions develop Sunday with northwest winds gusting 25 to
  35 mph.

- Chance for broader rainfall increases during the first half of next
  week.

- Colder air and lake effect snow showers are possible through the
  latter half of next week.

&&

.DISCUSSION...

Majority of observing sites are reporting clear skies this morning,
which is in line with nighttime satellite imagery that shows the
cloud shield contracting toward the Ohio Valley/East Coast. That
said, the impacts of this cloud deck linger toward daybreak as
temperatures in the Saginaw Valley/Thumb are running roughly 10-15
degrees cooler than southern locations where radiative cooling is
just now ramping up. Sub-zero 850mb temperatures exist across most
of the cwa, which combined with thickening mid/high cloud by this
afternoon keeps daytime highs capped in the low-mid 40s.

Quick transition back to an active pattern occurs this evening as a
clipper races across Ontario, drawing a cold front across the Great
Lakes overnight. Models have trended toward a stronger, closed
surface low with a more pronounced surface trough extending into
Lower Michigan. Still, this system struggles with moisture as column
saturation remains disjointed with the onslaught of a mid-level dry
slot and narrow low level moisture convergence along the front.
Model precipitation fields continue to generate most of the QPF
close to the surface low/over the lakes, although the stronger low
has spread the forecast precipitation shield a bit further south.
Did add in slight chance PoPs across the Thumb as a result of these
trends, but still think the depth of the dry air will be tough to
overcome to keep most of SE Michigan dry overnight.

Strong isentropic downglide begins immediately behind the front,
with the initial subsident layer trapping low cloud Sunday morning.
Should see this begin to mix out by mid-day, especially as the
inbound surface high provides a steady feed of drier Canadian air
overhead. Increasing mixing depths quickly intersect with the 35-40
knot low level wind field, resulting in breezy conditions Sunday
afternoon. Gusts up to 35 mph will be possible, with highest gusts
across the Thumb region (closer proximity to the low). Also of note
on Sunday is the onset of warm advection into the Great Lakes, in
which h8 temperatures gradually climb into the positive single
digits by Monday. High temperatures both Monday and Tuesday are
forecast to be in the 50s, well above normal for late November.

Dry conditions persist through early Tuesday, ahead of the next pair
of weather systems and a marked shift toward cooler conditions by
the end of the holiday week. Models continue to show two waves
ejecting out of the Pacific this weekend, remaining well out of
phase with the southern stream wave being the first to impact SE
Michigan Tuesday. Main impact from this will be widespread
precipitation, with a weakening trend to the system expected as it
tracks through. Above normal warmth ensures p-type is all rain. The
trailing northern stream wave shows more impact potential,
especially as it interacts with the existing surface low upstream.
This system draws a strong cold front across the Great Lakes
Wednesday, kickstarting the advertised cold temperatures for the
holiday weekend. The colder air flowing over the still warm lakes is
a standard setup for lake effect potential, although it is too far
out for additional details to be discerned.

&&

.MARINE...

High pressure in place today will support light northwest to west
winds under 15 knots.  Low pressure tracking through Ontario tonight
will send another cold front through the Central Great Lakes.
Guidance has trended toward a deeper low with a more southerly
track, generating gusty winds behind the front as 850 MB temps are
progged to bottom out around -6 C. Northern Lake Huron will see the
strongest gusts to around 35 knots, prompting the issuance of a Gale
Warning. Elsewhere, winds look to gust in the 20-30 knot range
behind the front on Sunday, with Small Craft Advisories issued for
all of the Lake Huron nearshore as a result. Ridge of high pressure
quickly builds in Sunday evening, allowing for winds to subside
Sunday night below headline thresholds. Light to moderate southerly
return flow then develops early next week.

&&

.PREV DISCUSSION...
Issued at 1101 PM EST Fri Nov 21 2025

AVIATION...

Dry and stable low level conditions will exist tonight and Saturday
as a ridge of high pressure tracks through the region. This will
maintain VFR conditions, within some lingering thicker high based
cloud overnight. Limited window for shallow fog formation late
tonight should skies clear prior to sunrise, but with a sufficient
gradient likely remaining a mitigating factor. Thickening mid level
cloud arrives Saturday evening as winds shift from northwest to
southwest in advance of a cold front. Cold front arrives Saturday
night bringing renewed lower cloud development by Sunday morning.

DTW THRESHOLD PROBABILITIES...

*  Low for cigs aob 5000 ft late Saturday night.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Gale Warning from 7 AM to 4 PM EST Sunday for LHZ361-362.

     Small Craft Advisory from 7 AM to 4 PM EST Sunday for LHZ421-422-
     441>443.

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

$$

DISCUSSION...MV
MARINE.......MV/SF
AVIATION.....MR


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