412
FXUS63 KDTX 010614
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
114 AM EST Mon Dec 1 2025

.KEY MESSAGES...

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

- Light accumulating snow tonight, with 1 to 2 inches expected for
  Metro Detroit and areas south.

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

&&

.AVIATION...

NW low-level flow (2-6 kft AGL) backs W overnight which supports
decreased lake stratocumulus. In the absence of cloud aloft, a
period of SKC will occupy portions of the airspace into Monday
morning as lower column ridging moves in. VFR conditions extend
through most of Monday while high cloud streams in and descends
throughout the daylight hours. This saturation process occurs in
response to an approaching upper level wave tracking south of the
state. Light winds organize out of the SE ahead of inbound
precipitation. Expect another round of snowfall Monday night into
Tuesday with lower visibilities and longer duration for the southern
terminals. Very light winds could back easterly as snowfall gets
underway. IFR ceilings and visibilities are likely to the south with
MVFR over PTK, and possibly FNT. MVFR ceilings/visibilities are most
uncertain for MBS, at least through 06Z.

For DTW...Clearer skies overnight and a decrease in winds,
eventually backing southerly. Weak low pressure system approaches
Monday evening bringing snowfall and ceiling/visibility impacts
amidst light ESE winds.

DTW THRESHOLD PROBABILITIES...

* High for ceiling at or below 5000 ft Monday evening and overnight.

* High for precipitation type as snow Monday evening and overnight.

&&

.PREV DISCUSSION...
Issued at 245 PM EST Sun Nov 30 2025

DISCUSSION...

Radar returns have been diminishing with the snow/trough rotating
through Saginaw Bay and now advancing through the northern Thumb
region with a little light snow (dusting to 1 inch). Subsidence,
drying, and clearing follows for tonight under northwest winds, but
some transient clouds downwind off Lake Michigan and even flurries
can`t be rule out with this cold airmass (negative low to mid teens
at 850 MB).  Otherwise, with the fresh snow cover and winds going
calm, mins in the teens look to be an easy call (assuming skies go
mostly clear), with single numbers likely across the normally
colder/better radiating locations. See MAV guidance and regional GEM
2 M temps.

The deep and large upper level low over Hudson Bay will continue to
support a progressive pattern this week, directing a series of waves
coming out of the Gulf of Alaska and diving southeast into the
Rockies. The current upper level energy over the Rockies/500 MB
trough will be arriving late Monday. The issue is there is two
distinct upper level waves embedded in the large scale trough, with
the southern wave and surface low tracking through
Tennessee/Kentucky taking with it the bulk of the moisture. Specific
humidity in the 850-700 MB layer struggles to get to 1.75 g/kg along
the southern Michigan border. None-the-less, the mid level jet does
look to clip southern Lower Michigan, providing sufficient elevated
forcing with saturation with respect to ice. Do think we can grind
out a half an inch to 2 inches in the Monday evening/night time
frame, supported by our local probabilistic guidance, with the I-94
corridor and points south seeing the highest totals.

Shortwave ridging on Tuesday with the next cold front on track to
move through late Wednesday. Little in the way of height falls and
moisture argues for just a chance of snow showers/dusting of snow.
Good cold advection behind the front, with 850 MB temps forecasted
to drop into the negative mid teens on Thursday, per 12z Euro. This
will set the stage for highs only in the 20s and mins Friday morning
in the single numbers. Strengthening southwest flow to end the work
week will allow for moderation, but temps still below normal into
the weekend. Will have to watch a Gulf Coast system passing to our
south on Friday as it heads into the Mid Atlantic States Friday
night. Phasing with the northern Stream appears to be too late at
this point.

MARINE...

Secondary cold front is pushing south of Lake Huron around time of
discussion before eventually clearing the southern Great Lakes this
evening. Strong northwest flow follows in the immediate wake of the
front supporting a 4-6hr period of 35-40kts across the central and
southern portions of Lake Huron. Outside of the Gale Warned zones,
some brief gales are likely over the Saginaw Bay (with Sag Bay Light
already reporting some) as well as over western Lake Erie in
preceding SW/WSW flow. For Erie however, window direction favors the
bulk of gales occuring over the open waters. Small Craft Advisories
are in effect for through late evening for the remaining
nearshore waters due to potential gusts to 30ks.

Sprawling ridge of high pressure aggressively builds in tonight
supporting a fairly rapid diminishing trend in winds across the
region. 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. Currently,
greatest chances (~50%) at seeing gusts to gales occur during the
preceding southwest aided by longer fetch over the central portions
Huron.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory until 7 AM EST this morning for LHZ421-441>443.

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

$$

AVIATION.....KGK
DISCUSSION...SF
MARINE.......KDK


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