Ann Arbor, Michigan 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

993
FXUS63 KDTX 290018
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
718 PM EST Fri Nov 28 2025

.KEY MESSAGES...

- Winter Storm Warning and Winter Weather Advisory in effect for
  widespread 5 to 8 inches of snowfall starting Saturday afternoon
  into Sunday.

- Below normal temperatures expected early next week. Highs in the
  20s and overnight lows in the teens.

- Another chance for accumulating snow is possible Monday night and
  Tuesday morning.

&&

.AVIATION...

Evening trend of lake effect snow persists amidst light showers and
flurries per KDTX radar. Intensity remains inconsequential as the
terminals have predominantly maintained VFR visibilities and ceiling
heights. Upstream observational trends indicate a low likelihood for
prevailing MVFR conditions for the rest of the evening and overnight
period as low-level flow briefly turns northwesterly. This, in
addition to advancing high pressure, ensures a drier feed of air,
which helps keep ceilings elevated. This also limits cloud depths,
reducing the amount of snow that can form aloft, favoring flurries
at the surface. Gusts drop-off at all sites tonight as the lower
column wind field continues to weaken.

Confidence is rising in a prolonged accumulating snow event Saturday
evening through Sunday morning. Top-down saturation processes will
be underway Saturday with ceilings and/or visibilities digressing to
MVFR, IFR, and possibly LIFR restrictions. Potential exists for
visibilities AOB 1/2 SM late Saturday evening, during the
anticipated peak of the event. This should occur just beyond the 00Z
TAF window (excluding DTW).

For DTW...Scattered flurries remain possible tonight with minimal
impact to ceilings or visibility. Impactful snow arrives Saturday
evening, dropping from VFR to IFR within a few hours. Potential
exists for LIFR conditions and visibilities AOB 1/2 SM during the
peak of the event, most likely between 01Z and 04Z Sunday. A PROB30
was added this cycle.

DTW THRESHOLD PROBABILITIES...

* Medium for ceiling at or below 5000 feet through 08Z this evening.

* High for ceiling at or below 5000 feet after 20Z Saturday.

* Low for crosswind threshold exceedence tonight.

* Medium for visibility 1/2 SM or less after 00Z Sunday.

&&

.PREV DISCUSSION...
Issued at 400 PM EST Fri Nov 28 2025

DISCUSSION...

Isolated to scattered flurry/light snow activity will continue
through this afternoon with the persistent cold northwest flow keeps
the lakes activated, though to a much lesser degree. The elevated
winds through this afternoon continue to result in wind chills that
hold in the low-mid 20s. Temperatures cool quickly into the 20s this
evening with the loss of daytime heating sending wind chills back
down into the teens for the overnight hours.

All attention turns toward the impending winter system arriving
locally tomorrow afternoon as a Pacific wave and associated surface
low moves across the Great Lakes. The exact track of the surface is
mostly in agreement in the ensemble space with a track across
southern Lake Michigan Saturday night into central/southern Lake
Huron by late Sunday morning. There are subtle differences in track
and timing, but trends have lead to a slightly later start time for
the impactful snowfall. Could see some snowflakes begin to fall
along western portions of the CWA as early as 1 pm depending on now
quickly saturation occurs. The higher rate snowfall looks to arrive
more towards 4 pm and after with the peak of this event landing
between 6 pm and midnight across southeast Michigan. Snow should
continue through all of tonight, though intensity should gradually
wane in the 1 am to 7 am time frame. Then snow tapers off late Sunday
morning into the early afternoon.

The set up continues to point to a widespread several inches of snow
accumulation event within a 12 to 15 hour window. Deep layer moist
isentropic ascent ahead of this low pressure system with a coupled
upper level jet structure supports this extended period of lift.
Embedded areas of stronger forcing associated with FGEN which mark
the peak time frame of this event where likelihood of higher snowfall
rates will exist. Snow rates will reside in the quarter inch to
three quarters of an inch per hour through much of the event while
FGEN brings potential for 1 inch per hour rates or greater. Higher
rates will be supported by solid vertical motion through the DGZ at
times, but confidence in duration and exact location of these more
intense bands is on the lower end. However, latest HREF this morning
points towards areas along the I-94 corridor to the southern border
with highest chance to see 1 to 1.5 inch per hour snow rates.

Sounding profiles and BUFKIT analysis suggest a normal snow (11:1 to
13:1 ratios) to start the event with potential for a transition to a
wet snow or even a rain/snow mix across far southern eastern
portions of the CWA, including the Detroit Metro area, and
transition to larger flakes for northern portions of the CWA. Not
completely sold on any transition to a rain/snow mix based on the
look of forecast soundings. While surface temperatures will be in
the upper 20s to lower 30s, the thermal profiles on forecast
soundings showing more than enough cold air for snow to be
maintained if surface temperatures climb slightly above freezing
tomorrow morning. And not completely sold that the dry air will
strip moisture from the DGZ to remove ice from the cloud.

QPF with latest NBM guidance has come in on the high end for 24 hour
totals between 18Z Saturday to 18Z Sunday with QPF in the 0.50 to
0.60 inches which in turn has increased the snowfall forecast. There
is still some potential that these may be slightly too high and
could land more in the 0.4 to 0.5 range. Highest confidence to
achieve 7 inches of snowfall in this 24 hour period is across
western portions of the CWA: the Tri-Cities where high ratio snow
comes into play and down towards the southwest portions of the CWA
where higher snow rate potential resides. Have opted for the Winter
Storm Warning for these areas as confidence is just high enough to
move forth with a warning. The remainder of the area will be
borderline warning and have opted for a high end advisory with 5 to
7 inches of snow accumulation. The weakening trend in forcing, lower
ratio potential, and possibly lower QPF bring cause to hold off for
now as we are still out about 24 hours or slightly more from the
arrival of more intense snow. It certainly remains possible to see
an expansion of the warning as more data comes in tonight and
tomorrow morning.

Gusty conditions follow the back side of this system as lake effect
snow showers becomes the predominate drivers of light snow showers
that carry through Sunday afternoon. Any additional accumulations
beyond 18Z are expected to be light. Very cold temperatures settle
into the region for the early week as high temperatures top out in
the 20s and overnight lows in the teens. Active pattern continues in
the extended as the next chance for accumulating snowfall will come
Monday night.

MARINE...

Ohio Valley high pressure maintains influence through tonight
supporting continuing weakening of northwesterly winds. Pattern
shift occurs Saturday afternoon as the next low ejecting out of the
Midwest begins to encroach on the Great Lakes. Winds organize out of
the south-southeast during this time with a steady strengthening
through the evening hours as the low center reaches lower MI. While
this flow carries some warmer air north, magnitude is not enough to
set up a truly stable overlake thermal profile allowing a portion of
a 50kt low level jet to mix down to the surface over the southern
Great Lakes and southern third of Lake Huron (roughly south of Port
Austin). Gusts Saturday night for these waters likely top out around
30kts with a sporadic gust to gale force not completely out of the
question. For the rest of the central Great Lakes, winds peak closer
to the 20-25kt range. Low is forecast to track northeast directly
over Lake Huron Sunday morning and eventually into the Georgian
Bay/Ontario by Sunday afternoon. This allows a secondary arctic cold
front to drop across the Great Lakes late Sunday afternoon-evening
ushering in renewed cold air advection on NW flow. Model guidance
today has been consistently trending stronger with this
front/trailing cold advection resulting in solid potential (50-80%)
for a 4-6hr period of 35-40kt gusts over northern/central Lake Huron
late day Sunday. A Gale Watch has been issued for all open waters
north of Harbor Beach as a result. Some occasional gales are
possible over the open waters south of Harbor Beach however given
the northwesterly wind direction, confidence in 3+ hours of 34kt
gusts is too low at this time to include in the watch.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Winter Storm Warning from 3 PM Saturday to 10 AM EST Sunday for
     MIZ047-048-053-060-068-075-082.

     Winter Weather Advisory from 3 PM Saturday to 10 AM EST Sunday for
     MIZ049-054-055-061>063-069-070-076-083.

Lake Huron...Gale Watch from Sunday afternoon through Sunday evening for
     LHZ361>363-462.

     Small Craft Advisory until 4 AM EST Saturday for LHZ421-441.

     Small Craft Advisory until 10 PM EST this evening for LHZ422-442-
     443.

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

$$

AVIATION.....KGK
DISCUSSION...AA
MARINE.......KDK


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