331
FXUS63 KDTX 301757
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1257 PM EST Sun Nov 30 2025

.KEY MESSAGES...

- A Winter Storm Warning and Winter Weather Advisory are in effect
thru 10 am. Additional accumulation of up to 2 inches through the
morning hours.

- Below normal temperatures continue through next week. Highs in the
20s and overnight lows in the teens will be prevalent from Monday
onward.

- Light accumulating snow is forecast Monday night and Tuesday
morning with 1 to 2 inches possible for Metro Detroit and areas
south.

- Dusting of snowfall or light snow accumulation will possible late
Wednesday ahead of an approaching cold front.

&&

.AVIATION...

MVFR ceilings will prevail through today as a cold front moves
through the area this afternoon. Southwest winds gusting to around
30 knots are being observed across the southern metro terminals ahead
of this front. Winds will be veering to west and eventually
northwest this evening as winds settle to around 10 knots. A few
isolated light snow showers/flurries will be possible this afternoon
as the front carries some lake moisture with it. Best chance across
MBS and FNT with TEMPO groups and PROB30 groups for remainder of the
terminals. Dry air behind the front will bring higher chance to see
VFR conditions for tonight as the gradient weakens bringing light
winds towards 12Z tomorrow morning.

For DTW...Gusty SW wind veers to W towards 23Z, presenting a low
probability to exceed crosswind threshold. Ceilings likely below
5,000 feet through the remainder of the day before trying to scatter
out tonight.

DTW THRESHOLD PROBABILITIES...

* High for ceiling at or below 5000 ft through this afternoon, then
  medium this evening.

* Medium for lake effect snow flurries the rest of the day.

* Low for crosswind exceedence this afternoon.

&&

.PREV DISCUSSION...
Issued at 911 AM EST Sun Nov 30 2025

UPDATE...

Based on the incoming snow reports, looks like 4-7 inches of snow
fell across the bulk of southeast Michigan, with the highest reports
across the Tri-Cities region where the low tracked and snow to liquid
ratios were better. The low is now exiting Central Lake Huron with
the trailing cold front slowly sweeping through southeast Michigan,
triggering additional snow showers the rest of the morning. Even so,
will allow the headlines to expire at 10 AM as additional snowfall
amounts should be a dusting to 1 inch. Temperatures are also
borderline freezing, and main roads appear to be in pretty good
shape.

Cold advection for the afternoon into early evening hours will
steepen the low level lapse rates and generate some modest cape.
However, the cape is under the dgz, thus would expect any scattered
snow showers that develop to produce a dusting to half an inch at
best. The exception would be across the northern Thumb region, where
another inch or two will be possible. This is due to being
underneath/close to the mid level circulation/cold pool and where
some enhanced low level convergence sweeps through.

PREV DISCUSSION...
Issued at 337 AM EST Sun Nov 30 2025

DISCUSSION...

Early morning surface analysis shows a 1007 mb low centered over
southern lake Michigan, accelerating to the northeast in response to
the arrival of the main height fall center associated with
broadening longwave troughing. Ongoing widespread area of light
intensity accumulating snow featured along the eastern flank and
within a broad region of ascent will maintain residence for several
more hours. Noted brief uptick in forcing also materializes invof of
the sfc low and trailing frontal zone mid-late morning. This will
yield a longer duration window for additional accumulation mainly
from Flint to the thumb and points northwestward. An additional one
to two inches of accumulation thru the morning, higher totals north
of metro Detroit. Ongoing winter headlines will remain in place
through the duration to capture the backend response.

Brief period of drying offers some reduction in moisture depth
within the immediate wake of the lead cold front for midday.
Limited cold air advection with this feature will sustain a
temperature near freezing. Secondary stronger cold front forecast to
track north to south between 19z and 23z. Narrow axis of greater
moisture quality along the advancing convergence zone will bring a
brief increase in snow shower potential during this time. Best
ascent focused east of I-75 and north of Detroit, with additional
accumulation of an inch or less mainly focused across the thumb
region. Firm west-northwest gradient in the wake of the low, with
modest improvement in mixing depth within the backdrop of ongoing
weak caa affording daylight gustiness into the 30 mph range.

Turning notably colder and drier tonight as northwest flow increases
depth along the downstream flank of inbound high pressure. Model
guidance consensus lends support toward greater nocturnal clearing.
Forecast tentatively highlights this potential, while acknowledging
the possibility for some degree of ongoing lake moisture flux to
allow some lake cloud to drift into portions of the area overnight.
Assuming a meaningful window of clear sky to capitalize on the fresh
snow cover, then Monday morning lows will arrive a solid 10+ degrees
below normal with values well in teens. This means a cold start to
the work week with highs again below average Monday. Benign wx
throughout the Monday period with conditions governed by weak low
and mid level ridging.

Next chance of light accumulating snow arrives Monday night. A
stronger mid level wave noted on water vapor entering the Pacific
Northwest and additional minor shortwave energy still over British
Columbia will progressively track across the Conus in tandem over
the next 48 hours. Fairly strong consensus still that these features
will maintain just enough separation through at least the SE MI
latitude. This favors a more muted overall response locally, as
favorable upper jet positioning and associated deeper forced ascent
target the Ohio valley. Gradual moistening process through sustained
yet weak isentropic ascent will work against a very dry ambient
profile. Assuming sufficient column saturation /most questionable
north/, then supportive environment exists for a light qpf event to
materialize overnight. Highest probability outcome for a range in
accumulation from .5 to 2 inches, with highest amounts focused south
of I-94.

Stretch of seasonably cold temperatures firmly entrenched heading
into the midweek period. Arctic cold front tied to a vort max
sweeping across the northern great lakes will effectively reinforce
this early December cold. Coldest conditions noted Thursday and
Friday, as highs hold in the 20s while overnight minimum wind chill
dips below zero Friday morning. The late day frontal passage
Wednesday offers potential for snow shower production, albeit again
working with a generally lean moisture profile. Closed low churning
over the southwest conus will eventually eject downstream and may
offer a greater opportunity for accumulating snow Friday night, but
still plenty of variance within the ensemble solution space with the
treatment of the governing dynamics.

MARINE...

Mature low pressure lifts northeast across Lake Huron into the
Georgian Bay/Ontario over the course of the morning. This results in
veering winds across the southern Great Lakes from south-southeast
early this morning to the west-southwest by late morning. While a
few gusts to around gales are possible over these waters through the
morning, particularly Lake Erie, shift to offshore flow keeps better
gale potential out over the open waters. Wind shift does however
lead to a rapid drop in water across the western Erie basin with low
water advisories in effect through the bulk of today. As the low
departs for Ontario, a secondary arctic cold front is drawn over the
central Great Lakes resulting in a sharp rise in northwesterly winds
by afternoon. 35-40kt gales remain likely across the central and
southern waters of Lake Huron into early this evening. A sporadic
gust to near gales is possible over far northern Lake Huron and the
Saginaw Bay however potential duration is too marginal to include in
the current gale warnings. For the remainder of the region, gusts
peak around 30kts.

Sprawling ridge of high pressure aggressively builds in tonight
supporting diminishing winds. High center is set to swing across the
Ohio Valley Monday maintaining light flow for the southern half of
the central lakes. As for the northern, broad low pressure over the
Hudson Bay compresses the gradient across the northern Great Lakes
preventing a true relaxation of the wind field resulting in
persistent southwest gusts up near 20kts Monday/Monday night. A
system trailing the high crosses the Ohio Valley late Monday-Tuesday
offering light snow chances but otherwise brings minimal local
marine impacts. Next significant system arrives Wednesday as a
strong arctic cold front drops out of northern Ontario resulting in
both strong preceding southwest winds and trailing northwesterly
winds as the coldest air of the season thus far moves over the Great
Lakes.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory until 10 PM EST this evening for LHZ422.

     Gale Warning until 10 PM EST this evening for LHZ362-363-441-
     462>464.

     Small Craft Advisory until 7 AM EST Monday for LHZ421-442-443.

     Small Craft Advisory until 2 PM EST this afternoon for LHZ441.

Lake St Clair...Small Craft Advisory until 10 PM EST this evening for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 10 PM EST this evening for LEZ444.

     Low Water Advisory until 10 PM EST this evening for LEZ444.

&&

$$

AVIATION.....AA
UPDATE.......SF
DISCUSSION...MR
MARINE.......KDK


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