419
FXUS63 KDTX 020456
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1156 PM EST Mon Dec 1 2025

.KEY MESSAGES...

- Light accumulating snow tonight. South of M-59, 1 to 3 inches of
  accumulation expected, with Monroe County seeing the highest total.
  North of M-59, just a dusting to maybe a half an inch.

- Temperatures will remain well below normal throughout the week. The
  coldest conditions arrive Thursday and Friday with wind chill
  values bottoming out at or below zero.

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

&&

.AVIATION...

Light snowfall persists over the terminals tonight. Ceilings have
had to contend with formidable low-level dry air, therefore VFR
ceilings have held on longer than expected, for the southern TAF
sites. Visibilities have been more variable, fluctuating between VFR
and IFR, even heading into the peak of the event. Did trend more
optimistic with the 06Z TAF cycle, favoring MVFR conditions (instead
of IFR) into Tuesday morning. Snow concludes from west to east
between 09Z and 12Z. Gradient flow remains light and variable into
the morning hours, becoming westerly.

For DTW...Conditions settle into MVFR for the rest of tonight and
Tuesday morning. Still some opportunities for additional IFR
visibilities with any enhanced snowfall rates. Snow ends around 12Z
with ceilings eventually lifting to VFR, then scattering out.

DTW THRESHOLD PROBABILITIES...

* High for ceiling at or below 5000 ft through midday Tuesday then
  low Tuesday evening.

* High for precipitation type as snow tonight and Tuesday morning.

&&

.PREV DISCUSSION...
Issued at 242 PM EST Mon Dec 1 2025

DISCUSSION...

Extremely dry airmass in place over southeast Michigan this morning,
as 12z DTX sounding indicated a PW Value of 0.11 inches, right
around the daily min record.

Thick canopy of high clouds today, coupled with the cold start, has
resulted in temps holding around 30 degrees for the afternoon, a
good 10 degrees below normal.

Still looking a light snow developing this evening/tonight with
decent moisture advection, height falls/upper level PV advection,
and mid level frontal circulation. Top down saturation process may
take much of the evening to saturate the low levels however.
Specific humidity in the 850-700 MB layer still on track to rise to
1.3 g/kg north to 1.75 g/kg along the southern Michigan border.
Despite some of the weak forcing(9-12 hr)/moisture being used up to
saturate the low levels, snowfall accumulations of 1-3 inches are
expected south of M-59. Areas which look to reach 3 inches is Monroe
county and possibly southern Wayne county, as the flow at the sfc to
925 MB is light southeast off of Lake Erie, which should help
accelerate the moistening of the low levels and enhance the qpf a
bit. North of M-59, pronounced surface ridging holding on through
the night, and would expect accumulations a half an inch or less.

Shortwave ridging on Tuesday with the next arctic front still on
track to move through late Wednesday as a strong shortwave/spoke of
energy around the strong polar low near/over Hudson Bay rotates
through the northern Great Lakes Wednesday night. With a little
moisture flux off Lake Michigan and good low level convergence with
the front, do think a line of snow showers will develop. Low level
lapse rates steepen up and some modest cape is generated, which will
flirt with the DGZ. As such, could become a borderline scenario for
snow squalls, as there does look to be 40 knots of flow at 850 MB.
Exact timing of front and magnitude of the cold air sweeping in will
determine. Right now, 850 MB temps progged to drop into the
-15 to -20 C range over the Central Great Lakes Thursday morning,
per 12z Euro. Temps likely hold in the lower 20s during Thursday,
setting us up for mins of zero to 10 above Thursday night. Short
lived warming (but still below normal) ahead of another arctic front
on track to move through for the first half of the weekend, but
uncertainty with the southward push and how fast it washes out.

MARINE...

High pressure will continue to push off towards the east and away
from the Great Lakes this afternoon, while maintaining light winds
across the southern half of the region.  Over the northern Great
Lakes, persistent southwest flow will continue through tonight as
the broad low pressure system continues to reside over the Hudson
Bay region. A system trailing the high crosses the Ohio Valley late
this afternoon into 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.....KGK
DISCUSSION...SF
MARINE.......KDK/SS


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