938
fxus63 kdtx 210354
afddtx
area forecast discussion
national weather service detroit/pontiac mi
1154 pm edt sun sep 20 2026
.key messages...
- seasonably cool conditions will persist into the middle of week.
- areas of showers are possible again tuesday night into wednesday.
&&
.aviation...
low level moisture associated with the frontal zone has been pushed
south of the airspace, with cloud cover now focused above 10.0 kft.
localized pockets of low vfr/mvfr have been streaming off of saginaw
bay/lake huron, but are transient with low confidence in impacts to
the terminals. a similar pattern exists into the daytime hours, and
could see a brief period of broken 3.0-5.0 kft agl ceilings as
diurnal mixing ramps up in the morning. otherwise, northeast flow
persists with sustained flow around 10-15 knots and gusts up to 25
knots. wind direction stays locked in through the taf period.
d21/dtw convection...thunderstorms are not anticipated through the
forecast.
.dtw threshold probabilities...
* low for ceilings at or below 5000 feet.
&&
.prev discussion...
issued at 400 pm edt sun sep 20 2026
discussion...
showers continue to dissipate as expected from north to south as
drier air filters into the low levels. this process is the result of
split flow moving in aloft and 1028 mb surface high pressure
building out of central ontario. a wind shift/cold front is being
driven south by the strengthening anticyclone, and will eventually
steer gradient flow northeasterly. despite the influx of a drier
canadian air mass, stratocumulus clouds are expected to linger
overnight given the cold advection over lake huron. cooler again
tonight, with temperatures dipping into the 40s for some locations
farther north.
readings hold below seasonal averages through the first half of the
week, with mainly dry conditions prevailing as the ridge influence
takes command. the exception will be closer to the ohio border where
a shortwave moves from the plains into the ohio valley, before
closing off and stalling. expect vicinity showers at times monday
through tuesday, although the rest of southeast michigan ought to
stay dry and breezy, particularly during the afternoon hours as the
ridge/subsidence wins out. thermal troughing maximizes across the
midwest by wednesday with 850 mb temperatures dropping into the mid
(perhaps low) single digits (celsius). the nam shows that the
coldest air should filter across lake erie, setting up a north-to-
south thermal gradient over southeast lower, with portions of metro
detroit possibly seeing highs capped aob 60f.
the synoptic pattern should lock up midweek as the closed mid/upper
low orients in rex block formation, immediately south of the ontario
anticyclonic wave. a southern stream wave will fold into the ohio
valley and break the stationary waves late wednesday into thursday,
offering some potential for showers, more so for the southern half
of the forecast area. it will take some time before temperatures
begin to recover, as easterly lower column flow hangs on toward the
end of the workweek.
marine...
the central great lakes reside on the southern fringe of broad
northern ontario high pressure through the first half of this week.
the combination with a lingering stalled frontal boundary over the
ohio valley results in a respectable gradient across the region
maintaining moderate northeasterly winds through tuesday (gusting 20-
25kts with 30kts possible in the saginaw bay). waves rippling along
the frontal boundary could offer some sporadic shower chances over
the southern great lakes though influence of high pressure is
expected to keep most of the area dry. westward drift of high
pressure leads to a shift toward more easterly flow wednesday though
with little to no reduction in wind speeds. gales remain unlikely
though onshore flow warrants long duration small craft advisories
for all nearshore waters.
&&
.dtx watches/warnings/advisories...
mi...none.
lake huron...small craft advisory until 10 pm edt wednesday for lhz421-422-
441>443.
lake st clair...small craft advisory until 10 pm edt wednesday for lcz460.
michigan waters of lake erie...small craft advisory until 10 pm edt wednesday for lez444.
&&
$$
aviation.....mv
discussion...kgk
marine.......kdk
you can obtain your latest national weather service forecasts online
at www.weather.gov/detroit.