271
FXUS63 KDTX 031355
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
855 AM EST Wed Dec 3 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 near or below zero.

- Arctic front will bring scattered snow showers this afternoon and
evening, with accumulations from a dusting to under an inch.

&&

.UPDATE...

The lower tropospheric frontal boundary is scheduled to move across
Se Mi late this afternoon and evening. There is ongoing low level
moisture advection off Lake Mi into the Saginaw Valley. RAP soundings
suggest it will take into the afternoon for the depth of the
moisture to reach ice nuclei and thus produce snow showers. Model
soundings and cross sectional analysis do at least indicate moisture
depth supporting light snow showers late in the day as the shallow
frontal circulation moves across the area. Although the lake moisture
feed may wane farther south, the region of mid/upper level moisture
over Iowa and nrn IL will move across the southern half of the
forecast area late this afternoon and evening, allowing the rather
weak ascent to at least produce some snow showers, with possibly a
little better flake size than what may be observed across the north.
In short, this is expected to be a high likelihood event for snow
showers but with minimal accumulations (dusting to half inch).

&&

.PREV DISCUSSION...
Issued at 603 AM EST Wed Dec 3 2025

AVIATION...

Expansive area of stratus featuring a cloud base at IFR to lower
MVFR will persist throughout the daylight period. This exists as
prevailing southwest flow turns modestly gusty ahead of an
approaching arctic front. Several hour window at any one location
for possible light snow shower development this evening along the
advancing cold front. Post-frontal wind shift to northwesterly with
some lingering gustiness overnight. Some degree of low level drying
with modest mixing will favor a trend toward VFR cloud as arctic air
funnels into the region during the early morning hours Thursday.
possible late tonight.

For DTW...Low stratus entrenched through the day. Window for
brief snow shower development 23z-02z.

DTW THRESHOLD PROBABILITIES...

* High for ceiling at or below 5000 ft through tonight.

PREV DISCUSSION...
Issued at 414 AM EST Wed Dec 3 2025

DISCUSSION...

Persistent anomalous upper troughing over Hudson Bay will maintain
influence over the Great Lakes this forecast period, with prolonged
well below normal temperatures expected through the rest of the week
and into next week. A lobe of vorticity will swing around the upper
low tonight, sending a reinforcing shot of arctic air across the
region behind a strong cold front. Ahead of the front, brisk
southwest flow will develop today as a LLJ passes overhead. The warm
air advection associated with this jet will remain elevated and the
resultant 15-25mph breeze will hold wind chills in the teens and
lower 20s today even as temperatures peak in the lower 30s.

The front will reach the Saginaw Valley in the afternoon and track
southeast through the evening hours. Model guidance continues to be
very lean on QPF as there will be a lot of mid-level dry air to
overcome before deeper saturation occurs, and most of the inbound
sfc-700mb moisture will be pooling out ahead of the front where
ascent is disorganized and shallow. A few light pre-frontal snow
showers or flurries will be possible, then a quick round of trailing
post-frontal snow showers follows later this evening as a brief
intersection of steepening low-level lapse rates, boundary layer
moisture, and frontal forcing occurs. A few hi-res runs produce
around 30-50 J/KG of SBCAPE in the Saginaw Valley which would
support a brief heavier burst of snow as a higher end scenario, but
the overwhelming model signal is for a muted response with these
showers. A dusting to a half inch of accumulation will be the most
likely outcome through tonight. Additional flurries may continue
overnight as the inbound cold air mass sends the DGZ down into the
boundary layer with any lingering clouds capable of producing a few
flakes.

Strong cold advection will keep the boundary layer well mixed
tonight with northwest wind of 10-15mph sending wind chill below
zero Thursday morning as temps plummet into the teens. High pressure
spreading across the southern lakes will ease the wind and bring
some sunshine on Thursday, but 925mb temps bottoming out near -14C
will maintain biting cold conditions with highs topping out near 20.
This is some 20 degrees below average highs and actually lower than
our average lows for early December. The degree of dry air will hold
any lake effect close to Lake Michigan and out of the local area.

The next lobe of arctic PV is slated to pivot across northern
Ontario Friday night, sending a cold front across the northern lakes
on Saturday. Ahead of this front, flow emerges once again out of the
southwest which will force the thermal trough away and offer a
warming trend from Friday into Saturday. A weak shortwave passing
across the Great Lakes Friday night will bring a slight chance of
snow, but the deeper moisture and ascent with this wave will be
focused north of the local area. The trailing portion of the front
will pass through later this weekend keeping below normal temps
around well into next week. The upper pattern holds a stronger jet
across the SE CONUS which leaves the Great Lakes in a relative lull
pattern void of stronger systems. Ensemble guidance breaks down this
pattern and brings in a more active storm track during the middle of
next week.

MARINE...

High pressure will finish sliding to the east coast today with the
next system set to move through today. Strong southwesterly winds
ahead of a cold front will have gusts reaching 25 to 30 knots into
the afternoon across central Lake Huron. A Small Craft Advisory is
in effect for Saginaw Bay and around to Harbor Beach for these
winds. A strong low pressure system over Hudson Bay will send the
cold front through this afternoon into the evening 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.

     Small Craft Advisory from 10 PM this evening to 4 PM EST Thursday
     for LHZ442-443.

Lake St Clair...None.
Michigan waters of Lake Erie...Low Water Advisory until 10 PM EST this evening for LEZ444.

&&

$$

UPDATE.......SC
AVIATION.....MR
DISCUSSION...TF
MARINE.......DRK


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