742 
FXUS63 KDTX 122030
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
330 PM EST Fri Dec 12 2025

.KEY MESSAGES...

- Bitter cold temperatures for the weekend into Monday. The coldest
  period will be Saturday night and Sunday morning. Expect wind
  chills to range between -15F to -10F by Sunday morning.

- Higher-end chances (50-60%) for light snow overnight. Snow
  accumulations will range from trace amounts up to a half-inch. A
  second chance (30-50%) for snow returns tomorrow afternoon and
  evening from I-94 south. Up to an additional half-inch will be 
  possible. 

- A dramatic warmup is then forecasted Tuesday-Thursday next week, 
as temps likely push aoa 40 degrees, setting the stage for potential 
rain.

&&

.DISCUSSION...

For the remainder of the afternoon and evening... A stratus deck has 
filled back in across SE MI which will sustain into the overnight 
hours under an established low-level inversion. Overnight, a strong 
PV anomaly now extending into northern Minnesota will continue to 
drive south into the northern Great Lakes. This will push a cold 
front over Michigan through the morning hours and will bring the 
chance for light accumulating snow. Both the shallow moist 
isentropic ascent up through 750mb ahead of the front and shallow 
convergence along the cold front itself will provide forcing for 
light snow chances overnight. Snowfall totals will range from trace 
amounts, up to a half-inch, with snow chances ending by 12Z. 

Strong cold air advection behind the front will bring decreasing 
temperatures through the day and will maintain a shallow but stark 
mixing layer which will produce wind gusts on the order of 20 to 30 
mph. Cold temperatures in conjunction with breezy conditions will 
produce wind chills around 0 degrees to the low single digits across 
SE MI by the afternoon hours. Flurries will remain possible given 
the shallow but strong lllr and sufficient 0-1km moisture, but 
moisture depths are too shallow to sustain accumulation. The one 
exception will be around I-94 and locations south in the afternoon 
and early evening as an upper-level wave rounds into the Ohio 
Valley. The northern precipitation shield of this feature has low-
end chances to clip southern Michigan which can bring light 
accumulations up to a half-inch. The updated forecast will hold Pop 
values to 20% up around the I-94, increasing to 50% near the border. 

The upper-level wave will continue to deepen across the Great Lakes 
through the weekend which will reinforce this significant cold air 
intrusion. While the magnitude of the wind speeds are not out of the 
normal, ensemble v-wind anomalies highlight the rarity of a 
sustained due-northerly fetch for mid-December, maximizing cold air 
transport. 850mb temperatures drop to near -20C and 700 mb 
temperatures to -26C by Sunday morning. Temperatures drop to around 
the 0 degree mark Sunday morning with wind chills ranging from -15F 
to -10F. A cold weather advisory will be under consideration for 
parts or all of the cwa for Sunday morning. Temperatures remain 
capped in the 20s for a high on Sunday, returning into the single 
digits overnight, with a return back into the 20s by Monday. 
Overall, expect temperatures to run roughly 20 to 25 degrees below 
normal through Monday. 

A Pacific wave will arrive onshore by the midweek which will deepen 
east of the Rockies before arriving across Michigan Thursday. Flow 
will back to the southwest in response to this wave, bringing 
temperatures back to near normal values Tuesday and likely above 
normal Wednesday-Thursday, with Thursday having the best chance to 
see temperatures peak aoa 40 degrees. While near the end of the 
forecast package, ensembles are showing moderate convergence 
highlighting moderate ivt ahead of a cold front on Thursday, 
bringing increasing confidence for rain showers.

&&

.MARINE...

Southwesterly winds will be slowly increasing through the rest of 
the day and overnight ahead of an approaching arctic front tied to a 
low pressure system that will track across Ontario tonight. Winds 
will turn westerly overnight behind the front and will increase with 
gusts up to 30 knots possible across parts of central and southern 
Lake Huron. Winds will remain elevated in the upper 20 knot range 
through Saturday with the coldest of the arctic air arriving late 
Saturday and overnight which will cause a boost to the winds to 
around 30 knots across the southern basin. At this time, guidance 
suggests we'll stay below 35 knot gales but that will be something 
to watch in the coming days. A long duration Small Craft Advisory is 
in effect this evening through Monday morning to account for this 
cold unstable airmass and period of wind and waves. The cold airmass 
and elevated winds will also lead to potential snow squalls and 
freezing spray as well.

&&

.PREV DISCUSSION...
Issued at 1148 AM EST Fri Dec 12 2025

AVIATION...

Sfc high pressure over Se Mi and dry ambient airmass has caused a 
general erosion of the stratus across much of Se Mi. Developing 
southwest flow in advance of an approaching cold front will focus 
the stratus deck across the MBS and FNT region this afternoon. 
Forecast expansion of the low clouds late this afternoon evening will
increase chances for low cloud re expansion across the remainder of 
the terminals later in the day. The cold front is forecast to track 
across Se Mi between 06Z and 12Z Saturday morning. Frontal 
convergence and enhancement off Lake Mi will support an area of light
snow showers along/in advance of the front. The overall brief period
of stronger forcing will keep snow accums less than an inch. 

For DTW...The window of opportunity for snow showers will be between 
06Z and 10Z. A forecast weakening of the forcing as the front moves 
across Se Mi suggests just a potential for a dusting of accumulation 
overnight

DTW THRESHOLD PROBABILITIES... 

*   Low in ceilings below 5000 feet this afternoon. Moderate tonight 
    and low Sunday.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory from 10 PM this evening to 4 AM EST Monday for 
     LHZ421-441.

     Small Craft Advisory from 10 PM this evening to 4 PM EST Saturday 
     for LHZ422.

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

$$

DISCUSSION...AM
MARINE.......DRK
AVIATION.....SC


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