297
FXUS63 KDTX 272000
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
300 PM EST Thu Nov 27 2025

.KEY MESSAGES...

- Cold weather will persist into the weekend. Winds will decrease
tonight. Wind chills will be in the teens tonight and Friday
morning.

- Accumulating snow is forecast late Saturday afternoon into Sunday
morning, preliminary forecast totals are in the 3 to 6 inch range.

&&

.DISCUSSION...

There will be a gradual departure of the upper low northeast of Lake
Huron tonight into Friday. Moist cyclonic flow will however persist
across much of Lower Mi through the night. This will at least
sustain a low chance for some light snow showers/flurries. The low
level flow will veer from WNW to NW during the night, which will
largely focus the better lake effect activity outside of Se Mi.
Despite some lingering gradient winds tonight, the airmass will be
quite cold with 850mb temps down around -12C. This will warrant min
temps into the 20s tonight and limit Friday highs to the lower 30s.
Strengthening mid level subsidence on Friday will lower the
inversion height. BUFKIT soundings suggest super saturation wrt ice
within the -15 to -17 C layer, suggesting some flurries out of the
diurnal strato cu field.

The mid level wave now over the Pacific Northwest will be the main
focus for the weekend as it emerges in the lee of the Rockies early
Saturday and lifts across the Ohio Valley/Great Lakes region
Saturday night. The 12Z model suite agree that the wave will drive a
region of strong mid level positive vorticity advection across Se
Mi. Upper jet coupling is also shown to support a broad region of
upper level divergence. Enhanced low level flow is also shown to
transport a decent low level theta e axis/moist plume into the Lower
Ohio Valley. System relative ascent in the mid levels is forecast to
be quite good across Lower Mi late Saturday/Saturday night. These
factors point to high probabilities for accumulation snow across all
of Se Mi as the column has trended a little colder the last few
model runs. Model cross sections indicate decreasing static
stability, although it is quite elevated. While this all suggests
some decent snow accumulation potential, there a few potential
limiting factors. The strongest push of mid level isentropic ascent
is forecast to be rather progressive. While moisture looks good for
widespread snow, specific humidities in the 800-700mb layer are only
forecast to rise to 2 g/kg (which raises some concerns that several
model solutions may be high on QPF). Forecast thermal profiles
indicate that dendrites may only be favored for a brief period,
which would cut down on snow to liquid ratios. Both the GFS and
ECMWF also have some indication that mid level drying may occur
later in the period (especially across the eastern portions of the
forecast area) which may also cut down on snow accums.

Among the array of probabilistic guidance, overall there is high
probabilities for total snowfall in the range of 3 to 6 inches by
Sunday morning, with at or below 50% for over 6 inches. Probabilistic
data for 3-hour snowfall during the peak of the event is high for 1
to 2 inches, generally low for 3 inches or more. These factors and
in coordination with WPC and surrounding offices will support
holding off on a winter storm watch for this issuance and will allow
for another model run to determine trends with this system. Aside
from the typical uncertainty in snowfall amounts, there remains some
spread in onset. Trends in probabilities are suggestive of snow
expanding across the area between 2 and 6 PM Saturday, then
persisting to some degree into Sunday morning.

&&

.MARINE...

Wednesday`s low pressure system continues to push deeper into
northeastern Canada allowing for a modest slackening in the pressure
gradient particularly across western and southern Great Lakes. This
trend has already been observed in Lake Clair with US ob sites no
longer reporting gales and western Lake Erie trending toward
consistent sub-gales. As a result, Gale Warnings for these waters
have been dropped in favor of Small Craft Advisories. Weakening
trend in gusts around the Thumb lag however favored to fall below
gales late this evening which offers some potential for these
warnings to be dropped early with the 10pm forecast update. Gradient
maintains better strength over the open waters of Lake Huron given
its closer proximity to the low supporting lower end gale potential
(34-38kt) through tonight into early Friday morning. Eventually the
northern edge of high pressure sliding across the Ohio Valley builds
into the central Great Lakes over the course of Friday supporting a
slow, but steady decrease in winds with sub 30kt flow developing by
the latter half of the day.

High maintains light winds to start the weekend however southerly
winds strengthen toward 20-25kts by Saturday night in advance of a
new low ejecting out of the southern Plains and into the southern
Great Lakes. Trends in the low track have shifted north, now
favoring the low center moving northeasterly over the Saginaw Bay
and central Lake Huron. Shift northward brings more chances for rain
to mix in with snow for all but the northern areas. Winds turn to
the northwest on the backside of the system second half of the day
Sunday setting up a renewed push of arctic air over the region.
Weaker low, compared to Wednesday`s low, and a faster progression
into northeastern Canada still lends to a less favorable gale setup.
That said, there is remains modest potential (~30-40%) for a few
hour period of entry level gales across northern/central Lake Huron
Sunday evening/early night.

&&

.PREV DISCUSSION...
Issued at 1200 PM EST Thu Nov 27 2025

AVIATION...

Westerly winds still gusting aoa 30 knots this afternoon, but
predominately low VFR cloud cigs with the daytime boundary layer
depths increased. Streamers/flurries from Lake Michigan around as
well. More significant band up around Saginaw Bay, and is expected to
remain east of MBS this afternoon. However, as low level winds veer
a bit more to the northwest this evening, its possible a few snow
showers impact the Tri-Cities region. Otherwise, bulk of the Lake
generated stratocu shrinks back toward Lake Michigan as subsidence
and some dry air takes hold this evening/tonight. This will support
periods of ceiling free skies over the taf sites, as streamer MVFR
clouds remain transient. Low confidence on timing of the breaks
however, and mostly erred on the cloudier side for the tafs.

For DTW.. Just some passing flurries possible this afternoon with
cigs holding under 5000 feet.

DTW THRESHOLD PROBABILITIES...

* High for ceiling 5000 feet this afternoon, medium tonight and
  Friday.

* Low for crosswind threshold exceedence today.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Gale Warning until 7 AM EST Friday for LHZ361-362.

     Gale Warning until 10 AM EST Friday for LHZ363-421-422-441>443-
     462>464.

Lake St Clair...Gale Warning until 4 PM EST this afternoon for LCZ460.

     Small Craft Advisory until 4 PM EST Friday for LCZ460.

Michigan waters of Lake Erie...Gale Warning until 4 PM EST this afternoon for LEZ444.

     Small Craft Advisory until 4 PM EST Friday for LEZ444.

     Low Water Advisory until 4 AM EST Friday for LEZ444.

&&

$$

DISCUSSION...SC
MARINE.......KDK
AVIATION.....SF


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