582
FXUS63 KDTX 181100
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
600 AM EST Tue Nov 18 2025

.KEY MESSAGES...

- Snow and sleet, changing to rain and melting snow is forecast
today, mainly southwest of a Saginaw to Mount Clemens line. Some
patchy freezing rain is possible around Adrian, Onsted and Chelsea.

- Dry conditions with highs mainly in the 40s are forecast Wednesday
and Thursday.

&&

.AVIATION...

The elevated front is lifting into southern MI early this morning
and will bring a period of mix precipitation and rain to a portion
of SE MI (Detroit tafs and possibly PTK) before pealing away to the
east this evening. Attention during the early morning has been on
temperatures upstream and nearby already warming between 32-34F with
dewpoints climbing to 28-32F. Elevated dewpoints will limit wetbulb
cooling which will in turn limit the duration and impact from any
light snow this morning. Will lean more toward period of -RASN which
could switch to all snow at times during heavier showers. Heaviest
showers exit the area by 18Z with light rain or drizzle persisting
through the evening. MVFR CIGS and some reduced vsbys will accompany
the precip before conditions improve to VFR overnight. Winds will be
light out of the east early then northeast. One thing we are still
watching is a possible secondary frontal band of precip this evening
which could produce some rain at FNT and PTK. Models are just
starting to show this potential so will leave out of the tafs at
this time.

For DTW... Dry air remains a factor in slower onset timing of snow
or rain/snow mix in the morning. Mid to late morning onset improves
the chance of above freezing temperatures at temperatures around the
area are already reaching 32 and above, a few hours earlier than
anticipated. So could start off with -RASN instead of just snow for
a couple hours.

DTW THRESHOLD PROBABILITIES...

* High for ceiling 5000 feet or less after 14z today, low after 08Z
  tonight.

* High for precipitation type of rain snow mix today transitioning to
  rain this afternoon. Low for all snow at onset for a couple hours
  around 14Z.

&&

.PREV DISCUSSION...
Issued at 545 AM EST Tue Nov 18 2025

UPDATE...

Precipitation is now approaching the far southern portions of the
forecast area. Surface temperatures within the upstream precip shield
have risen above freezing and are a degree or two above the latest
HRRR. This supports removing the chance for freezing rain in
Lenawee/Washtenaw Counties. Recent ACARS sounding at Toledo has a
fairly respectable depth to the warm layer, suggesting precip type
will be mainly rain near the Ohio border. The ACARS sounding out of
Detroit is colder and certainly more supportive of a snow/snow
pellets/sleet mix farther north. Upstream radar is supportive of
some sleet within the broader region of light rain. Based on latest
radar and hi res guidance, precip will expand across locals south of
an Ann Arbor to Monroe line by 13Z, then expand into at least the
southern portions of metro Detroit between 13Z and 16Z. A forecast
update will be issued to make some minor adjustments to reflect
current conditions and to remove the early morning portion for the
ZFPDTX product.

PREV DISCUSSION...
Issued at 300 AM EST Tue Nov 18 2025

DISCUSSION...

A compact mid level low rotating into Iowa this morning will track
across the nrn Ohio Valley late this afternoon/evening and weaken
into an open wave. A swath of rain is ongoing upstream as the mid
level height falls in advance of the approaching low interact with a
lower to mid tropospheric frontal boundary. As this wave progresses
east, the mid level fgen region will advance into the southern
portions of the forecast area during the morning. Of note is the
area of convection along the nose of the low level jet over south-
central IL/ern MO. The strongest low-mid level theta e advection
will progress across the Ohio Valley today along the nose of the
better low level inflow, which will also sustain a good deal of
elevated instability in this region. This will likely force a more
active response along the lower portions of frontal boundary,
generally south of the forecast area. This suggests some degree of
weakening of the response farther up the frontal slope over srn
Lower Mi, mainly this afternoon. These factors suggest precip
expanding into the southern portions of the area this morning, with
an overall weakening trend during the course of the afternoon.

The 00Z DTX sounding showed a formidable mid level dry layer.
Overnight temps across Se Mi are in the 20s, with sfc dewpoints
around 20. While the precip upstream is in the form of rain,
substantial wet bulb cooling will result in precip change over to
snow as it expands across far srn Lower Mi this morning. Model
soundings remain supportive of some slight warming of the column which
suggest some snow pellets and/or sleet. Any freezing rain signal
looks limited, with a little more probability in nrn/cntl
Lenawee/wrn Washtenaw counties. Sfc temps are forecast to rise above
freezing toward late morning. This combined with forecast low QPF
amounts will limit any snow accums to grassy surfaces, primarily
south of a Flint-Owosso to Detroit line. Residual mid level frontal
forcing, albeit weak, will warrant lingering chances for rain and/or
wet/melting snow across the south this afternoon. There are several
high res solutions which show a secondary mid level fgen response
along/south of the I-69 corridor this evening as the mid level wave
tracks into Ohio. This will be worthy of a chance of rain/snow.

Mid level negative vorticity advection and associated sfc high
pressure will expand across Lower Mi from the northwest on
Wednesday. A notable drying trend is forecast overnight into
Wednesday morning. This may even limit the extent of any strato cu
on Wednesday. Despite shallow mixing depths, the expectation for
some sun will push afternoon highs into the low to mid 40s
Wednesday. An upper low forecast to move into northern Ontario from
north central Canada will force a sfc cold front across Lower Mi
Thursday night. A strong confluence in the mid/upper level flow
across the southern Great Lakes is forecast to suppress the deep
moisture pool across the Ohio Valley, limiting the available
moisture along the cold front as it works across Se Mi. The last
several model cycles have trended drier with this front, which is
now being better reflected in the model blends. So only a low chance
for rain is now forecast along the front. Prefrontal warm air
advection on Thursday will allow temps to make a run at 50 degrees.

MARINE...

Low pressure slides across the Ohio Valley today, with the northern
edge of its precipitation shield lifting as far north as Port Huron
by this afternoon. A wintry mix is possible this morning before
changing to rain during the daylight hours. The resident northwest
flow regime will be dislodged toward more of a north-northeast flow
pattern by tonight as the low departs in favor of a northern stream
high pressure center. This high will gradually drift over the Great
Lakes through mid-week, reinforcing light winds and calm waves.
Winds flip to the southwest Wednesday night as the high moves into
eastern Ontario, with a cold front projected to impact the Great
Lakes to end the work week. This brings the next chance for elevated
wind/wave action and precipitation chances.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

AVIATION.....DRK
UPDATE.......SC
DISCUSSION...SC
MARINE.......MV


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