490
FXUS63 KDTX 271700
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1200 PM EST Thu Nov 27 2025

.KEY MESSAGES...

- Flurries/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 evening
into Sunday.

&&

.AVIATION...

Westerly winds still gusting aoa 30 knots this afternoon, but
predominately low VFR cloud cigs with the daytime boundary layer
depths increased. Streamers/flurries from Lake Michigan around as
well. More significant band up around Saginaw Bay, and is expected to
remain east of MBS this afternoon. However, as low level winds veer
a bit more to the northwest this evening, its possible a few snow
showers impact the Tri-Cities region. Otherwise, bulk of the Lake
generated stratocu shrinks back toward Lake Michigan as subsidence
and some dry air takes hold this evening/tonight. This will support
periods of ceiling free skies over the taf sites, as streamer MVFR
clouds remain transient. Low confidence on timing of the breaks
however, and mostly erred on the cloudier side for the tafs.

For DTW.. Just some passing flurries possible this afternoon with
cigs holding under 5000 feet.

DTW THRESHOLD PROBABILITIES...

* High for ceiling 5000 feet this afternoon, medium tonight and
  Friday.

* Low for crosswind threshold exceedence today.

&&

.PREV DISCUSSION...
Issued at 913 AM EST Thu Nov 27 2025

UPDATE...

The 12Z DTX sounding showed some degree of limitation with potential
convective depths this morning with some stability in the mid
levels. Colder mid level temps upstream will boost the equilibrium
levels this afternoon. However, ongoing low level dry air advection
will place a substantial amount of dry air in the sub cloud layer.
Persistent west-northwest winds will remain supportive of a moisture
feed off Lake Michigan. The dry air suggests mainly scattered snow
showers and/or flurries through the rest of the day, but with
nothing more than a dusting expected. A dominate lake band
originating from Lake Superior impacted northern Huron County earlier
this morning. Recent radar data indicate the band has broken apart
over the thumb, with some redevelopment offshore. Can not rule out
some additional extensions of the dominate banding over northern
Lower Mi extending into the thumb region today. For this reason,
minor additional snow accums (around an inch) will be carried in the
thumb today. Otherwise, gusty winds will maintain a brisk holiday
with afternoon wind chill readings holding in the 20s.

PREV DISCUSSION...
Issued at 430 AM EST Thu Nov 27 2025

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.

&&

.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.

&&

$$

AVIATION.....SF
UPDATE.......SC
DISCUSSION...MV
MARINE.......KDK


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