Expert Forecast Opinion

201
FXUS63 KDTX 141720
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1220 PM EST Sat Nov 14 2026

.KEY MESSAGES...

- A narrow corridor of lake effect rain showers (briefly mixed with
melting snow) persists today and tonight, mainly along the southern
Lake Huron shoreline.

- Mostly cloudy skies expected elsewhere through the weekend.

- Brisk morning winds drop wind chills into the 20s (isolated upper
teens) Sunday morning.

- Dry weather expected area-wide Monday through Thursday with a
steady warming trend.

&&

.AVIATION...

Surface high pressure spans a broad area from northern Ontario to
the Gulf coast, along the MS river valley, but is slow to move
eastward this afternoon and tonight. This maintains NW flow that is
cold enough to support widespread activation of Great Lakes clouds
across Lower Mi through at least Sunday morning. Satellite and
surface observations leading into this afternoon report MVFR below
2000 ft across the region that grinds up above 2000 ft with a few
breaks at times during peak daytime heating. Model soundings
indicate an adequate subsidence inversion developing just in time to
trap broken MVFR tonight and Sunday morning. Another round of
diurnal enhancement fights against inbound high pressure for slow
improvement Sunday afternoon.

For DTW... Ceiling remains below 5000 ft during any breaks of MVFR
this afternoon. NW wind off the slightly higher terrain is also
capable of producing MVFR ceiling variability tonight through
Sunday.

.DTW THRESHOLD PROBABILITIES...

* High for ceiling at or below 5,000 feet this afternoon and
tonight.

&&

.PREV DISCUSSION...
Issued at 232 AM EST Sat Nov 14 2026

DISCUSSION...

The synoptic environment continues to evolve as expected given the
highly amplified omega block draped across CONUS. Southeast Michigan
remains positioned near the eastern longwave trough axis which will
undergo a restructuring during the course of the day. The primary
upper low is expected to become absorbed by a retrograding 528 dam
500 mb low tracking southwestward along the St. Lawrence River,
which then settles over the Northeast this evening. Meanwhile,
upstream longwave ridging drifts eastward, easing into the Upper
Midwest/Minnesota. This results in the local area becoming
positioned between the complementary waves while an embedded speed
max transits due south over the central Great Lakes. The CVA induces
subtle forcing aloft to maintain localized areas of lake effect
precipitation for most of the day. However, coverage will be limited
to the eastern Thumb and locations along the immediate southern Lake
Huron shoreline, after northerly flow backs north-northwesterly
later today.

Thermodynamically, deterministic solutions indicate slight
degradation of the existing thermal trough as weak warm advection
slips in from the encroaching ridge. 850 mb temperatures should lift
by 2 or 3 C today, but still anomalously cold, resulting in highs
only in the mid 40s. Regarding precipitation type within the narrow
corridor of lake effect showers, forecast soundings reveal eventual
drying through the DGZ as flow backs between 5 and 7 kft AGL. This
limits the likelihood for ice nuclei, therefore, rain is the
preferred hydrometeor form as the day progresses. Note that some
snowflakes could still mix in during the morning hours today given
deeper saturation depths. Not as chilly overnight thanks to
insulating lake stratocumulus, but still colder than normal.

The lower tropospheric anticyclone builds northeastward out of the
Mid-Mississippi Valley Sunday, weakening boundary layer flow. Lower
column winds now look to retain a northwesterly, if not north-
northwesterly trajectory well into the afternoon hours, but the lack
of shear should suffice in concluding residual lake effect
precipitation by mid afternoon. Likewise, lake induced clouds will
linger into Sunday evening, and likely into the overnight hours.
Significant column drying and subsidence ensue Sunday night as the
longwave ridge crosses overhead. 1030 mb surface high pressure
gradually builds into the Ohio Valley with time which flips weak
gradient flow southwesterly.

Temperatures moderate throughout next week as the ridge flattens but
lingers from southern Appalachia into the Southeast. This preserves
an increasingly confluent stream of milder Gulf-modified air from
the southwest. A progressive Pacific wave unblocks the pattern and
is what causes the ridge to de-amplify, but mid-range guidance
continues to delay the arrival of embedded shorter wavelength
cyclonic features until Thursday or Friday. Still, most of the QPF
associated with the passing surface reflection tracking across the
UP/Lake Superior also holds farther north. Solutions also differ in
the passage of the attendant cold front, with warm advection
possibly hanging on as the next wave`s deeper core preserves
southwesterly flow into the weekend. Global models suggests 850 mb
temperatures could make a run at 10C late next week, suggesting 2m
temperatures above 60F may be achievable. Some ensembles families
support this case, in addition to the lack of measurable
precipitation before the weekend.

MARINE...

Northwest flow holds today which will sustain breezy conditions
across Lake Huron. Gusts ranging between 20 to 25 knots are
expected. Ongoing lake effect rain bands will also continue across
the southern Lake Huron basin through the day. The Small Craft
Advisories remain in effect from the outer Saginaw Bay to Port
Huron, aligned where elevated wave heights reside. An isolated
waterspout cannot be ruled out with any stronger rain shower. High
pressure to then build in over the Great Lakes starting tomorrow.
This will end lake effect precipitation across southern Lake Huron
by the afternoon as wind speeds decrease. The influence of high
pressure will bring an extended period of dry weather through the
midweek period along with lighter winds.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...None.

Lake Huron...Small Craft Advisory until 10 AM EST Sunday for LHZ421-441>443.

Lake St Clair...None.

Michigan waters of Lake Erie...None.

&&

$$

AVIATION.....BT
DISCUSSION...KGK
MARINE.......AM


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