370
FXUS63 KDTX 180800
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
300 AM EST Thu Dec 18 2025

.KEY MESSAGES...

- Mild with late day/early evening temps in the mid 40s to lower 50s
  toward the southern Michigan border.

- Increasing rain coverage today, with widespread rainfall late in
  the day/early this evening, along with gusty winds of 30-40 mph,
  especially on Friday.

- There is the potential for any moisture on roadways to flash freeze
  Thursday night as arctic air moves back into the region.

- Scattered-numerous light snow showers late tonight-Friday morning,
  with isolated embedded snow squalls possible into the afternoon.
  Snowfall accumulations of a dusting to perhaps an inch in the heaviest
  activity. Expect the Friday morning commute to be impacted and
  allow for extra time.

&&

.DISCUSSION...

Tight circulation and strong upper level wave tracking through North
Dakota this morning with additional upper level energy/jet dropping
southeast on the backside into the Central Plains. Massive area of
aggressive 500 MB height falls this evening, with -140 M from Lower
Michigan to Kentucky. Subsequently, a very strong south-southwest
low level jet (70 knots) will track through southeast Michigan early
this evening, transporting near record moisture for Mid December
standards, as NAM/HRRR indicating 850 MB dew pts of 7 C. 00z
Regional Gem/HRRR were also very aggressive with surface dew pts,
reaching near 50 degrees, which seems a bit aggressive. However, do
think it is prudent to carry max temps around 50 degrees across
Detroit Metro area and points south. For reference, the record high
at Detroit for today is 54 degrees set in 1939.

Although there will be occasional light rain showers increasing in
coverage during the day, the main show is in the 22-04z window as
the very impressive cold front tracks through. The wind shift from
south to west will be dramatic, and will be conducive for a rope
like feature/thin line of higher reflective/heavier rain embedded
within a larger swath of rain. These narrow lines bring concern for
high winds (> 45 MPH) as they attempt to tap into the departing
strong low level jet. Can`t even rule out thunder with the strong
forcing, but showalter indices do look to stay positive. Banking on
enough near surface stability with the frozen ground over southern
Michigan to keep wind gusts in check, but this is something that will
have to be watched closely, and can be better handled with a short
fused product. Higher confidence in 40+ mph wind gusts with the stout
low level cold advection behind the front, as 850 MB temps crash
to -16 C around 12z Friday. 700 MB cold pool reaches Lake Huron by
15z Friday already, thus subsidence and lowering inversion heights
should attempt to limit snow shower intensity from the westerly bands
off Lake Michigan. Will continue to advertise high scattered- low
numerous coverage of snow showers with accumulations of a dusting up
to 1 inch in the strongest activity. Sfc-925-850 mb temp/dew pt
gradient really tightens up 9-12z time frame and is positioned to
provide the focus in the I-69/M-59 corridors. There still looks to be
a low chance/isolated snow squall with modest cape briefly
intersecting the DGZ late morning/midday with surface temps in low to
mid 20s.

The fast tracking Pacific storms look to continue to track along the
Canadian/United States border through the weekend into early next
week. One cold front to roll through Saturday, with large area of
high pressure tracking through Sunday-Monday morning, underneath
some good upper level confluent flow. Warm advection/elevated warm
front looks to be arriving late Monday/Monday night, but best
moisture/forcing looks to be over the Western Great Lakes region.
The next cold front then progged for Tuesday already. Bottom line,
precip chances look low for the extended, and any amounts will be
light. Temperatures are also borderline/marginally cold, thus
rain/snow lines will have to be worked out if precip does in-fact
occur. Outgoing NBM pops are slight chance at best.

&&

.MARINE...

Southerly flow will continue to strengthen through the day, peaking
late this afternoon as the low level wind max arrives just ahead of
a cold front. Strongest winds (70+ knot low level jet) stay
elevated, but shallow mixing will still be sufficient to bring gale
force gusts (35-40 knots) to the surface across the open waters.
Colder water temps and ice cover maintain more stability toward the
shoreline and cap gusts around 30 knots. Gale Warnings are thus in
effect for the open waters with Small Craft Advisories along the
nearshore, unless observations warrant an upgrade. The front will be
defined by a band of rain that transitions to snow on its back edge,
as well as a quick pop in wind gusts this evening. This will be
followed by a brief lull in winds late tonight, but a quick return
to gale force gusts by Friday morning amidst strong cold advection.
The colder airmass is more favorable for gales to extend into the
nearshore zones Friday, with a Gale Watch in effect late Thu night-
Fri for the Lake Huron nearshore. Winds Friday veer from SW to NW,
sustained around 30-35 knots, which will support lake effect snow
showers. Combination of lake effect snow and gusty winds will
generate snow squalls Friday before winds subside Friday night as
high pressure fills in. Another low arrives Saturday night, which
will be the next opportunity for headlines.

&&

.HYDROLOGY...

Yesterday`s afternoon sunshine and temperatures in the low to mid
40s lead to decent snow melt. Even more aggressive snow melt will
occur this afternoon and evening with rain and temps pushing 50
degrees. Even so, with expected basin average rainfall totals at or
slightly better than half an inch, no flooding is anticipated. There
will however, be ponding of water on low lying areas and roads.
Rises on area rivers will occur, but well below bankfull.

&&

.PREV DISCUSSION...
Issued at 1132 PM EST Wed Dec 17 2025

AVIATION...

Respectable boundary layer cooling around metro Detroit this evening
under clear skies and light winds has led to some MVFR fog. The fog
should remain shallow through the night as rapid strengthening of
the wind fields occur atop the shallow nighttime stable layer. These
increasing winds (40-50 knots at 1500 to 2000 feet) will continue to
warrant the mention of low level wind shear into the early morning
hours. Subtle daytime heating and warm air advection into the
boundary layer will transition the low level wind shear to gusty
winds at the surface, with peak gusts expected to top 25 knots Thurs
afternoon.

The increase in south wind fields will be preceding a strong sfc
cold front, forecast to pass across Se Mi late Thurs afternoon and
evening. Low level moisture across the Lower Ohio Valley will lift
into srn Mi during the course of the morning as a result of the
strengthening south flow. This will result in lowering ceiling
heights (MVFR to IFR) during the day Thursday. Broad large scale
ascent along/ahead of the cold front and associated upper level
trough will result in a widespread region of rain Thurs afternoon
and early evening, with the potential for some shallow convection
along the surface cold front.

For DTW...The trajectory of the moisture transport suggests the
lower clouds (MVFR and IFR) will hold west of metro into Thurs
afternoon. The cold front is forecast to pass across metro between
23Z and 02Z Thurs evening. There is a chance for some high intensity
showers embedded within the broader region of light rain during this
time period.

DTW THRESHOLD PROBABILITIES...

* High in ceilings aob 5000 feet Thursday and Thursday night.

* High in precipitation type being all rain Thursday and Thursday
  evening.

* Low in crosswinds thresholds being exceeded after 08Z Friday.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Gale Warning until 7 PM EST Friday for LHZ361>363-462.

     Small Craft Advisory until midnight EST tonight for LHZ421-441>443.

     Gale Watch from late tonight through Friday evening for LHZ421-422-
     441>443.

     Low Water Advisory from 7 AM this morning to 7 PM EST Friday for
     LHZ422.

     Small Craft Advisory from 7 AM this morning to midnight EST tonight
     for LHZ422.

     Gale Warning from 7 AM this morning to 7 PM EST Friday for LHZ463-
     464.

Lake St Clair...Small Craft Advisory from 7 AM this morning to 7 PM EST Friday for
     LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory from 7 AM this morning to 7 PM EST Friday for
     LEZ444.

     Low Water Advisory from 4 AM to 4 PM EST Friday for LEZ444.

&&

$$

DISCUSSION...SF
MARINE.......MV
HYDROLOGY....SF
AVIATION.....SC


You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.