191
FXUS63 KDTX 171017
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
517 AM EST Tue Feb 17 2026

.KEY MESSAGES...

- Dense fog this morning from northern Detroit suburbs to Flint,
  Port Huron, and Thumb.

- The next round of precipitation is on schedule for tonight and
Wednesday. All rain is expected with a chance of freezing rain north
of M 46.

- Mild temperatures persist through Thursday.

- A rain/snow mix moves in by Friday followed by a temperature drop
back toward mid/late February normals this weekend.

&&

.AVIATION...

Calm winds with early morning clear skies allowed areas of dense fog
to develop across a greater portion of SE MI, with the later arrival
of mid-level clouds doing little to hamper fog development. LIFR to
IFR visibility restrictions are expected through the morning hours
with visibilities ranging between a quarter-mile up to 1 mile.
Expansion of a robust stratus deck with fog now across the northern
Thumb will continue to be monitored for expansion through KMBS. The
latest hi-res model highlight veering winds this morning which would
allow it to continue to expand south, which is highlighted in the
prevailing forecast. Given the overachievement of fog this morning,
lingering dense fog will be likely after daybreak, with eventual
lifting of the fog to stratus, before better scouring out occurs
through the afternoon. The exception will be across KMBS, where the
aforementioned stratus may linger over the terminal through the
afternoon and evening.

DTW THRESHOLD PROBABILITIES...

*  Moderate for cig/vsby below 200ft and/or 1/2SM this morning.

* Low for cig at or below 5000 feet this afternoon. High overnight
  Wednesday.

&&

.PREV DISCUSSION...
Issued at 353 AM EST Tue Feb 17 2026

DISCUSSION...

A unique fog scenario is unfolding within a weak cold front/trough
that was initially low cloud-free for much of the night. This
allowed radiational cooling in and near the surface trough where mid
to upper 30s Td pooled resulting in a large area of dense fog from
the northern Thumb to Port Huron, Flint, and the northern suburbs of
Detroit. A Dense Fog Advisory is in effect until 10 AM for this
area. Some of the fog could leak south toward the I-94 corridor,
however the effect of mid and high clouds is holding surface T up in
the lower to mid 40s. Plan to monitor trends there and also
northward toward the Tri Cities.

The cold front settles and stalls just south of the Ohio border this
afternoon, and remains precipitation-free as the 500 mb ridge axis
moves overhead and stabilizes the frontal zone. It will be dry but
there will be a substantial cloud component within the low to mid
levels of the frontal zone all across southern Lower Mi. Increasing
easterly surface and boundary layer wind builds the fog into a
stratus layer, especially north of I-69, while mid and high clouds
continue to thicken over the entire region this afternoon. The
clouds and wind direction combine to knock temperatures down 5 to 10
degrees compared to Monday. Highs today range from the upper 30s
along the Lake Huron shoreline and Saginaw Bay to the upper 40s
interior west of I-75, a good representation of the wind direction
influence across the area.

The front awaits activation by the large low pressure system that is
on schedule to organize across the northern to central Plains this
afternoon. The Pacific Coast 500 mb low is well on the way through
the Rockies this morning accompanied by a 170 kt 250 mb jet, both of
which will induce strong lee side cyclogenesis across the Plains
this afternoon. Organization of the surface system includes a strong
low level jet spreading eastward along the front that has access to
Gulf modified air for transport into the low to mid levels of the
frontal zone over the Great Lakes. The strong moisture transport
quickly produces an expanding pattern of showers on the leading edge
and within the advancing theta-e ridge to near widespread coverage
by midnight. Given the limited temperature rebound today, readings
are expected to drift down slightly below freezing this evening in
the northern Thumb and northern reaches of Midland and Bay counties
making that area vulnerable to a few hours of freezing rain. This
forecast update increases the freezing rain footprint in the
northern Thumb where easterly wind brings in colder air unobstructed
from Ontario across a mostly frozen southern Lake Huron. There is
greater coverage potential but still a relatively short time window
for icing to occur as even there readings are projected to quickly
rise above freezing after about 3 AM tonight. The temperature trends
will be monitored closely for potential of anything more than
current the current light glaze of icing expectation.

The peak of the rain event occurs late tonight and early Wednesday
as the 850-700 mb frontal zone surges south to north across Lower
Mi. Interesting that elevated instability was adequate for a few
thunderstorms in northern Lower Mi yesterday afternoon which points
to even greater potential as model data takes 850 mb LI negative
during peak moisture transport and on the leading edge of the mid
level dry slot. This dry slot brings a quick end to the rain by
early Wednesday afternoon while the warm front/occlusion stalls in
the vicinity of the I-69 corridor. The frontal position allows the
warm sector to build north of the Ohio border up through metro
Detroit where highs in the lower 60s remain in reach while readings
could be limited to the upper 30s again in the northern Thumb.

The Midwest to Great Lakes system stalls and begins to fill
Wednesday night and Thursday as the next larger scale wave breaks
away from the Pacific Coast long wave trough. This system moves
inland and into the central Plains Thursday on a track into the
western Great Lakes Thursday night and Friday where it merges with
the leftover frontal zone from the Wednesday system. Longer range
model runs indicate a strong occlusion over Lower Mi that favors
rain at onset changing to a rain/snow mix as the system pivots
through the area Friday and exits Friday night. Temperatures then
drop back toward normal mid/late February readings for next weekend.

MARINE...

The Great Lakes reside within a deformation zone this morning,
leading to split flow with northwest winds across Lake Huron and
southwest winds across Lake Erie. Low pressure is already well
organized and moving into the Plains at issuance, which will
organize winds out of the east through the day as it moves closer.
Elevated portions of the system`s warm front expand north across the
Great Lakes Wednesday, drawing the low level jet northward but
leaving enough depth to the cold air to mix a few thousand feet off
the deck. Guidance continues to support a threat for gale force wind
gusts daytime Wednesday across northern Lake Huron where the cold
air is deepest. There is enough confidence in the setup for a Gale
Warning upgrade with the early morning forecast issuance. Marine
areas south of Sturgeon Point likely see rain with this system, with
increasing chances for wintry mix to the north. Next round of
elevated wind potential comes Friday as another low pressure system
impacts the Great Lakes region.

HYDROLOGY...

Widespread rain moves in ahead of a strong low pressure system and
warm front tonight and Wednesday. Moderate probabilities for 0.25"
to 0.5" of rain are expected south of I-94 and low to moderate
probabilities for 0.5" to 0.75" to the north across the rest of SE
Michigan. The rain will occur on top of a melting snowpack that had
a Snow Water Equivalent analysis ranging between 0.5" to 1". The
combination of rain and snow melt on frozen ground may lead to rises
on area streams and rivers. Ponding of water on roads is also
possible, especially where drains could be blocked by snow and/or
winter debris.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Dense Fog Advisory until 10 AM EST this morning for MIZ049-054-055-
     060>063-068>070.

Lake Huron...Gale Warning from 4 AM to 4 PM EST Wednesday for LHZ361-362.

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

$$

AVIATION.....AM
DISCUSSION...BT
MARINE.......MV/BT
HYDROLOGY....BT


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at www.weather.gov/detroit.