701
FXUS63 KDTX 220401
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1101 PM EST Fri Nov 21 2025

.KEY MESSAGES...

- Mainly dry conditions this weekend with a warming trend by Sunday.

- Areas near the Michigan/Ohio border could see a few light showers
late this evening or early tonight.

- 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.

&&

.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.

&&

.PREV DISCUSSION...
Issued at 258 PM EST Fri Nov 21 2025

DISCUSSION...

Post-frontal airmass characterized by decreased low cloud fraction
and westerly winds gives way to drier evening conditions, for most.
21.18Z vicinity NUCAPS sounding revealed a 33C dewpoint depression
at 600 mb (13 kft AGL) with several ASOS/AWOS sites reporting SKC
for the 20Z observation time. Attention turns to the MI/OH border
this evening as a mid-level shortwave trough (visible on GOES water
vapor imagery over MO) tracks through the Ohio Valley tonight. A
sharp ThetaE gradient exists near the state line, and the most
favorable moisture profiles are located further south. Isentropic
perspectives show an area of broad moist ascent and resultant shower
activity, potentially clipping southern Lenawee and Monroe Counties.
Overall expectation of minimal coverage still hinges on the arrival
of shortwave ridging moving into the Upper Midwest. Isentropic
descent and the advection of dry continental air function as a
barrier, degrading the advancing moisture plume. Ultimately,
uncertainty persists regarding the the northern extent of nocturnal
shower activity. Nudged the sliver of 15 percent (Slight Chance)
PoPs a bit further north around 03Z, with a minor extension in
duration. The rest of the forecast area will remain dry heading into
Saturday with lows near seasonal normals (lower 30s).

Cold core Canadian upper low and associated thermal troughing
progress into Quebec on Saturday, while the 0C 850 mb isotherm
bisects Southeast Michigan. This affords a seasonably cooler day
across the local region with highs in the mid 40s. Weak north-
northwest flow gradually backs toward the southwest later in the
day. This occurs in response to Lower Michigan high pressure
becoming displaced by a clipper system digging into the Upper
Midwest. Accompanying uptick in cloud cover aloft precedes the
advance of the system`s cold front. Surface progs suggest the
frontal passage moving west to east from approximately 06Z and 12Z
Sunday. Plume of low-level moisture pooling ahead of the boundary
appears insufficient for the generation of precipitation (rain)
since mid-level drying will already be well underway.

Synoptic environment shifts to a more progressive pattern early next
week, featuring the release of a longer wavelength closed low. This
wave looks to phase with a land-falling Pacific northern stream
trough, resulting in rapid deepening over the northern Plains. The
system becomes occluded with a broad precipitation shield.
Uncertainty remains with regard to timing and intensity of warm
sector precipitation. Climatologically mild through the first half
of the week, before the system`s composite front facilitates a sharp
change in temperatures for the latter half of the week. Lake effect
showers (snow) are then possible amidst the influx of colder air and
persistent CVA.

MARINE...

Westerly post frontal winds late this afternoon have mostly peaked
out in the 15-25 knot range, strongest across the northern half of
Lake Huron. Winds will gradually weaken tonight and veer around to
the northwest, with winds under 15 knots on Saturday. Low pressure
tracking through Ontario Saturday night will send another cold front
through the Central Great Lakes. Northwest winds look to gust in the
20-30 knot range behind the front on Sunday, as 850 MB temps are
progged to bottom out around -6 C. However, a ridge of high pressure
quickly builds in Sunday evening, allowing for light winds Sunday
night, with light to moderate southerly return flow then developing
early next week.

&&

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

$$

AVIATION.....MR
DISCUSSION...KGK
MARINE.......sf


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