017
FXUS63 KDTX 270930
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
430 AM EST Thu Nov 27 2025

.KEY MESSAGES...

- Wind chills in the teens this morning expected to rise into the
20s by this afternoon.

- Snow showers and gusty winds (30 to 35 mph) continue today. Most
areas will see a dusting up to an inch of snow, although locally
higher amounts are possible mainly in the Thumb region.

- Quieter pattern Friday and Saturday with highs in the mid 30s.

- Increasing confidence in accumulating snowfall Saturday night into
Sunday.

&&

.DISCUSSION...

Broad cyclonic flow has become firmly established across the Great
Lakes overnight, with a notable Lake Superior-Lake Michigan
connection generating multiple bands of lake effect snow across the
state. Two notable areas of lake effect snow are reaching SE
Michigan: one plume that is focused south of I-94, and the more
organized linear banding over northern Lower Mi that is just now
reaching into the Thumb. Both areas are starting to exhibit a more
organized presentation on radar, likely as the diurnal minimum
provides a brief window of decoupling. For most of the night,
however, the cold and turbulent boundary layer has been quite
disruptive to any linear organization. The southern stream LES lacks
the Lake Superior connection, and exhibits a more cellular, broad
plume of light-moderate snow that is likely to result in just minor
accumulations (dusting to highly localized 1 inch) for areas south
of I-94 through the first half of the day. The northern stream band
affords a bit less confidence considering the lake aggregate effects
and possible (albeit small) influence of Saginaw Bay. The latest
short-term models have backed off of accumulations in the Thumb, now
in the 1 to 3 inch range although will still keep a close eye on the
region for any achievement. Gusty winds and reduced visibility in
snow showers will again produce variable travel conditions across SE
Michigan for the holiday.

For the rest of SE Michigan: west winds of 30 to 35 mph will
continue throughout the day, with wind chills this morning in the
teens and only forecast to rise into the low 20s this afternoon.
Occasional flurries and/or light snow showers remain possible
outside of the main lake effect bands, amidst a healthy coverage of
lake stratocu.

High pressure begins to build into the region Friday, with broad
subsidence stripping away column moisture. Lingering lake effect
snow showers will gradually taper toward flurries with the
increasing reliance on Lake Michigan moisture flux. High pressure
influence also aids in relaxing gradient winds for a less windy end
to the holiday week. Flow eventually shifts to the southwest Friday
night, fully shutting off the lake response for a mainly dry daytime
period Saturday. Highs both days in the low to mid 30s.

Trends are becoming more favorable for accumulating synoptic
snowfall Saturday night-Sunday. Origins of this system begin with a
cluster of Pacific shortwaves that move into the lee of the Rockies
late Friday, just as return flow is ramping up into the Plains.
Surface low development and a blossoming precipitation shield are
expected across the central Plains by Saturday morning as the lead
shortwave connects with the moisture transport. The low is forecast
to eject out of the TX Panhandle and lift toward the Great Lakes by
Saturday evening, with the broader trough taking on a neutral-
negative tilt as it arrives. This helps draw left exit region
dynamics into SE Michigan, along with a period of strong mid-level
warm advection that will be a primary source of broad synoptic
forcing throughout the event. Direct influence of the sfc-700mb
circulation may introduce banding potential as well, but not placing
much confidence in this yet as synoptic details are still being
sorted out.

Variance in the model guidance so far has been tied mostly to the
phasing (or lack thereof) of the embedded waves, with the latest
trends increasing the separation between them. This has favored a
weaker/more progressive overall synoptic system and a more southerly
track to the low, nudging the forecast toward a colder solution that
favors snow as the main p-type. There is still some question as to
how far north the system`s warm sector gets, which is one of the
main sources of uncertainty with this forecast especially toward the
Detroit suburbs and points south. These locations are more likely to
see temperatures near or even above freezing for a portion of the
event. Overall though, operational model output and the
interquartile range of LREF members increase confidence that winter
headlines may be needed this weekend.

The Great Lakes will reside on the cold side of the baroclinic zone
through the early half of next week. Temperatures Monday and Tuesday
struggle to break out of the mid 20s, while the sharp thermal
gradient over the TN Valley is a prime track for additional waves to
follow, keeping an active pattern in play through the rest of the
forecast period.

&&

.MARINE...

Low pressure is in the process of pushing away from the Great Lakes
over northern Ontario early this morning. This shifts winds to the
northwest across the region with widespread 35-40kt gales finally
becoming established over the northern portions of Lake Huron. For
the southern waters, overnight peak gusts of 40-45kts linger through
the early morning hours, though with the gradual departure of the
low, gusts weaken slightly favoring speeds more in the 35-40kt
range. Northwesterly gales hold throughout the day today as does
lake effect snow showers as arctic air settles over the Great Lakes.
Influence of the remnant trough doesn`t begin to wane until tonight
keeping entry level gales possible into early Friday morning,
particularly across the southern half of Lake Huron. Eventually the
northern edge of high pressure sliding across the Ohio Valley
gradually builds into the central Great Lakes over the course of
Friday supporting a slow, but steady decrease in winds with sub 30kt
flow developing by the latter half of the day.

High maintains light winds to start the weekend however southerly
winds strengthen toward 20-25kts by Saturday night in advance of a
new low ejecting out of the southern Plains and into the southern
Great Lakes. This system looks to roughly track along northern Lake
Erie toward the St Lawrence Seaway late Saturday night-Sunday
bringing widespread snow (with some rain potentially mixed in the
south). Winds turn to the northwest on the backside of the system
second half of the day Sunday setting up a renewed push of arctic
air over the region. Weaker low, compared to Wednesday`s low, and a
faster progression into northeastern Canada lends to a less
favorable gale setup. That said, there is still some potential
(~30%) for a period of entry level gales across northern Lake Huron
Sunday evening/early night.

&&

.PREV DISCUSSION...
Issued at 1220 AM EST Thu Nov 27 2025

AVIATION...

Lake effect snow activity is still underway with ceilings settling
between low VFR and elevated MVFR stratocumulus. Radar and model
trends suggest mainly light/flurry activity for most terminals
overnight, with higher likelihood for visibility reductions due to
snow showers specifically at the southern terminals. Did TEMPO in
some IFR for DTW and YIP. Winds have held from a WSW direction past
prior expectations, and elevated sustained winds/gusts persist into
Thursday as the low-levels remain well-mixed. Lake effect snow
showers also continue into Thursday, albeit with somewhat lower
coverage. Adjusted PROB30s to TEMPOs for the midday hours for light
snow and MVFR ceilings, then prevailing for the afternoon and
evening hours given low confidence in which banded structures
intersect any TAF site. Daytime gusts hold in the upper 20 to lower
30 knot range Thursday, eventually trending westerly with borderline
VFR/MVFR ceilings.

For DTW..Light snow shower activity continues tonight with some IFR
visibilities and gusty WSW winds. MVFR/VFR conditions expected with
some improvement on Thursday, plus additional lake effect snow
showers.

DTW THRESHOLD PROBABILITIES...

* High for ceiling 5000 feet or less tonight, and medium Thursday.

* Low for westerly crosswind threshold being met tonight, then
  medium Thursday afternoon.

* High for precipitation type as snow tonight and Thursday.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Gale Warning until 7 AM EST Friday for LHZ361-362.

     Gale Warning until 10 AM EST Friday for LHZ363-421-422-441>443-
     462>464.

Lake St Clair...Gale Warning until 4 AM EST Friday for LCZ460.

Michigan waters of Lake Erie...Gale Warning until 4 AM EST Friday for LEZ444.

     Low Water Advisory until 4 AM EST Friday for LEZ444.

&&

$$

DISCUSSION...MV
MARINE.......KDK
AVIATION.....KGK


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