734
FXUS63 KDTX 040845
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
445 AM EDT Sun Oct 4 2026

.KEY MESSAGES...

- Narrow band of light showers possible this morning mainly north of
I-69.

- Seasonable highs today near 70 degrees.

- Below normal temperatures arrive Monday with highs only near 60
and lows falling into the 30s. Chance for frost is possible Monday
night particularly over the Saginaw Valley/Thumb.

&&

.AVIATION...

Mainly mid level clouds are present this morning, with some higher
based light showers working through areas mainly north of M-59.
Southerly winds will shift to the west this afternoon, increasing at
or above 10 knots. A SCT-BKN VFR Cu deck is expected, which may
linger into the evening as cold advection kicks in. Winds will veer
around to the northwest tonight, staying somewhat elevated in the
5-10 knot range. There could even be some transient, narrow lower
clouds as a Lake Superior to Lake Michigan moisture connection sets
up.

D21/DTW Convection... Thunderstorms are not forecast this period.

.DTW THRESHOLD PROBABILITIES...

* Low for ceiling 5000 ft this afternoon and evening.

&&

.PREV DISCUSSION...
Issued at 309 AM EDT Sun Oct 4 2026

DISCUSSION...

Deep potential vorticity troughing with phased upper level jet
dynamics will push across Southeast Michigan early today. Forecasted
height fields support negative tilting of the axis as it arrives but
with the strongest 1000-500mb height falls passing to the north and
east of the Upper Peninsula. A late timing of the deepening,
relative to Southeast Michigan, results in an extremely narrow
ribbon of moisture with shallow midlevel saturation.  Forecast
soundings support very dry air in the lowest 10.0 kft agl. Modestly
better lapse rates above 12.0 kft agl resides over the northern cwa
between 9-13z. The better potential to measure is north of the I 69
corridor with much of the area at less than 40% to exceed a 6 hourly
rate of 0.05 inches of liquid. Forecasted PoPs may be a little low
for the Tri Cities and Thumb but given the amount of dry air in the
low levels will maintain the inherited. Gradient flow with mixing
will result in a bump for surface winds this afternoon. West to
northwest this afternoon of 15 to 25 mph. Highs today will be in the
upper 60s to lower 70s, the true cold front not pushing through the
area until this evening.

Sharp geopotential height rises over the Great Lakes region will
support surface high pressure Monday and Tuesday. Much cooler
weather is expected Monday with highs in the upper 50s to around 60
despite full sunshine. Heart of the anticyclone will be overhead
Monday night with dewpoints forecasted to drop into the middle 30s.
With a calm wind environment the likelihood is high that a Frost
Advisory will be needed Tuesday morning for at least a portion of
the forecast area.

The next upper level jet packet with a cyclonically curved exit
region will push into the Great Lakes late Tuesday and Wednesday.
Will need to monitor the southward extent to the absolute vorticity
advection as it relates to the PoP forecast. The current forecast for
the probability of precipitation is low for the midweek period. The
forecast area looks to be perilously close to troughing which offers
uncertainty for PoPs heading into next weekend. Temperatures look to
be around normal next weekend.

MARINE...

High pressure over the central and eastern Great Lakes region will
gradually move over the Northeast through the end of the weekend as
low pressure tracks east across southern Ontario, remaining north of
Lake Superior. While this low is progged to remain well north of the
area, it is expected to intensify as it moves east towards the James
Bay area. This will result in a large-scale uptick in winds over the
region and a window for low-end gales over northern Lake Huron
Sunday night and Monday morning as cold air advection ushers in a
higher potential for destabilizing the boundary layer over the open
waters and mixing down stronger winds.

Further south on Lake St. Clair and the nearshore waters of Lake
Erie, similar south winds to start the day will become west and
eventually northwesterly by the end of the day. Winds will also
increase Sunday night into Monday; however, they will not be as
strong that far south and currently look to remain below small craft
advisory levels. Winds gradually weaken late Monday into Tuesday as
a transient area of high pressure briefly moves through the region.
We then see another system track north of the area, but will bring
another uptick in winds for mid-week.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Gale Watch from this evening through Monday morning for LHZ361-362.

     Small Craft Advisory from 11 AM this morning to 8 AM EDT Monday for
     LHZ421.

     Small Craft Advisory from 11 AM this morning to 2 PM EDT Monday for
     LHZ441.

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

$$

AVIATION.....SF
DISCUSSION...CB
MARINE.......CB


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at www.weather.gov/detroit.