Expert Forecast Opinion

109
FXUS63 KDTX 022336
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
636 PM EST Tue Dec 2 2025

.KEY MESSAGES...

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

- Arctic front will bring the potential for snow showers late
Wednesday, with a dusting to just under an inch of accumulation.

&&

.AVIATION...

Large scale forcing supports shortwave ridging aloft and high
pressure at the surface tonight across Southeast Michigan. First
glance of forecast soundings suggest a substantial lowering of the
inversion with time tonight which would usually help to dry the
lower troposphere out. However, difficult forecast as extensive MVFR
stratus deck is in place immediately to the south and west of the taf
sites this evening. Flow will eventually emerge out of the southwest
which will help advect moisture below the inversion and cloud to the
northeast into the taf sites. Developing pseudo warm sector ahead of
the cold front should aid in a lifting ceiling and breaks Wednesday.
The potential does exist for scattered snow showers along the cold
front 20z-00Z Wednesday. Included a TEMPO for snow showers at DTW
this issuance.

For DTW... Some breaks in the clouds exist in vicinity of DTW with
extensive stratus immediately to the south and west. Expecting
prevailing MVFR ceilings developing and holding for much of tonight.
Warm sector development will support VFR ceilings Wednesday. Did
time out some MVFR snow shower potential after 23z Wednesday.

DTW THRESHOLD PROBABILITIES...

* High for ceiling at or below 5000 ft again this evening and
Wednesday.

&&

.PREV DISCUSSION...
Issued at 306 PM EST Tue Dec 2 2025

DISCUSSION...

A sfc to 850mb mid level ridge axis will slide east of the forecast
area this evening. Increasing southwest flow in the wake of the
ridge and in advance of an arctic front will force warm air
advection atop the shallow cold layer, causing a lowering the
inversion during the night. In light of upstream observations, this
should hold a good deal of stratus overhead through much of the
night, which will limit nocturnal cooling and support lows in the
20s.

Mid level height falls within the base of a Hudson Bay upper low
will help drive the arctic front across Se Mi Wednesday afternoon
and evening. The prefrontal southwest flow will advect some added
low level moisture off Lake Michigan into the frontal system. Model
cross sectional analyses indicates the ascent along the front to be
fairly shallow with a limited duration of deep layer moisture
present. While post frontal low level lapse are steep, equilibrium
levels on model soundings are less than 6k ft. By the time the
column gets cold enough to support dendrites, aggressive drying will
occur. These factors will likely keep the coverage of any lingering
post frontal snow showers minimal. Model derived QPF is therefore
only a few hundreds, equating to generally a dusting to less than an
inch of total snowfall. Even the 90 percentile 24-hour snow accums on
the model blend has an inch or less.

The main impact associated with the front will be the cold airmass
which gets advected into Se Mi as 925mb temps are forecast between
minus 14 and minus 15 Thurs morning, warranting forecast highs in
the upper teens/low 20s on Thursday. This is a good 20 degrees below
early December averages. Model soundings suggest 20 to 25 knots in
the mixed layer Thurs morning, leading to gusty winds which will
force wind chill readings near or a few degrees below zero. The cold
air depth will be greater across the northern lakes, where lake
effect activity will be confined. Even with the low level flow
backing southwest during the afternoon, low inversion heights and
very dry air associated with sfc high pressure across the Ohio Valley
will inhibit lake effect activity off southern Lake Michigan.
Progressive flow shown by model solution indicate the high pressure
departing east by Friday as a short wave impulse traverses the
northern lakes. Continued limited moisture and forcing across Se Mi
will remain supportive of a dry forecast through the end of the work
week.

MARINE...

High pressure over the region today will slide eastward overnight
but remain in control of the eastern lakes. Southwesterly winds will
be increasing tonight as the gradient tightens from an approaching
trough that will send a cold front through the region Wednesday
afternoon. Wind gusts will reach 25 to 30 knots across Lake Huron by
morning which will necessitate the Small Craft Advisory that begins
tonight. A strong low pressure system over Hudson Bay will send the
cold front through in the afternoon with very cold arctic air
entering the region in the wake of the front. The front will flip
the winds around to the northwest while the arctic air increases the
winds gusts of 30 to 35 knots possible Thursday morning. Most
guidance still offers little support for wind gusts to reach gales
for any notable amount of time during this period so will continue
to hold off on any gale headlines and mention the potential for a
few gusts to gales instead.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory until 4 PM EST Thursday for LHZ421-422-441.

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

$$

AVIATION.....CB
DISCUSSION...SC
MARINE.......DRK


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