622
FXUS63 KDTX 011740
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1240 PM EST Mon Dec 1 2025

.KEY MESSAGES...

- Light accumulating snow tonight. Highest accumulation from Metro
  Detroit southward, with 1 to 2 inches expected.

- Temperatures will remain below normal throughout the week. The
  coldest conditions arrive Thursday and Friday with wind chill of
  single digits to lower teens.

- Arctic front will bring the potential for light snow late
  Wednesday, with some minor accumulation possible.

&&

.AVIATION...

A VFR mix of mid and high clouds covers SE Mi this afternoon as weak
high pressure is nudged eastward by the next wave of low pressure
entering the Ohio valley by this evening. It brings an area of snow
that is on schedule to spread into Lower Mi this evening and then
last much of the night. The entire terminal corridor sees at least
MVFR restriction for a few hours, although coverage and intensity
will be greater south of FNT where both IFR visibility and ceiling
are expected along with a general 1 to 3 inch accumulation. A few
hours of LIFR visibility carries lower probability of occurrence
this far north but upstream observations will be monitored for later
updates. Accumulating snow ends after 12Z, however a fog component
lingers in the col region between pressure systems and ceiling is
also slow to improve during the morning.

For DTW... Sub 5000 ft VFR is nearby to the north and west and
remains there as cloud layer wind increases from the south this
afternoon. Conditions then decrease rapidly into IFR this evening
with a 02Z snow onset time on schedule and a 2 inch accumulation the
most likely number at DTW. Snow ends around 12Z Tuesday while MVFR
lingers through the morning.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling at or below 5000 ft this afternoon, then high this
  evening through Tuesday morning.

* High for precipitation type as snow tonight.

&&

.PREV DISCUSSION...
Issued at 313 AM EST Mon Dec 1 2025

DISCUSSION...

Energetic north Pacific jet undercutting broader upper level
troughing emanating south of a predominant central Canadian polar
low ensures an extended stretch of higher magnitude cold by early
December standards along with potential interludes of at least light
accumulating snowfall during this 7 day forecast period. Low and mid
level ridging entrenched locally early this morning, immediately
downstream of a broadening corridor of height falls lifting across
the plains. This maintains a window of dry and stable conditions for
the daylight period today. Entrenched 850 mb temperatures below
-10C, translating into highs mainly aob 30 degrees.

Light snowfall event arrives tonight. An increase in mid level
southwest flow ahead of the approaching height fall gradient
associated with a weak pv feature will establish a weak corridor of
moist isentropic ascent starting this evening. Inbound moisture
quality proves sufficient in establishing adequate saturation to
generate light snow for most locations, but some areas generally
north of I-69 will likely maintain a much drier profile and could
lack depth to allow light snow production to reach the surface.
Roughly a 6-9 hour event window centered between 03z and 12z
tonight. Distribution in accumulation potential from north to south
ranging from a dusting to 2 inches, highest amounts focused south of
I-94.

After transient high pressure yields seasonably cold but benign
conditions Tuesday, attention shifts to the arrival of an arctic
front late Wednesday into Wednesday night as a piece of the polar
low wobbles southward into the great lakes. Gusty pre-frontal
southwest gradient emerges for the daylight period, as weak thermal
ridging noses into the region. Peak gust potential into the 30 to 35
mph range with dependence of degree of mixing. Little opportunity
for greater moisture recovery given mid level flow from a westerly
trajectory, so expectation remains for a limited response in terms
of snowfall production with a frontal passage currently projected
for the late evening hours.

Significantly colder conditions Thursday and Friday. This arctic
intrusion will feature temperatures that are a solid 20 degrees
below average, leaving minimum wind chill Friday morning at or below
zero most locations. Series of shortwaves anchored with the active
Pacific jet will stream east/southeast with time Friday into next
weekend. Very difficult pattern evolution to offer any meaningful
definition to potential opportunities for accumulating snow, given
an unsettled solution space in terms of strength, positioning and
timing of governing features. It remains within the envelop of
outcomes for this period to remain mostly dry and simply cold or
become active with one or more chances for accumulation.

MARINE...

High pressure slides across the Ohio Valley/southern Great Lakes
today maintaining light winds for the southern half of the region.
As for the northern half, 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 into tonight. A system trailing the high crosses
the Ohio Valley late today-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
(~40-50%) 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...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

AVIATION.....BT
DISCUSSION...MR
MARINE.......KDK


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