990
FXUS63 KDTX 310341
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1141 PM EDT Sun Aug 30 2026

.KEY MESSAGES...

- Periodic chances for showers and thunderstorms continue through
much of the week, with the highest coverage favored across northern
areas.

- Very warm and humid conditions are expected Monday through
Wednesday, though daily peak temperatures will depend on cloud cover
and precipitation.

&&

.AVIATION...

Regional observations and latest model guidance suggests low clouds
remaining north and west of MBS tonight, leaving higher based clouds
to prevail at the terminals. Boundary layer moisture may however be
sufficient to some fog development overnight, with the cloud canopy
limiting the coverage and duration. While probabilistic guidance
indicates a good chance for additional showers late tonight into
Monday morning, the array of deterministic solutions adds some doubt
as to the coverage and extent of any morning precip. Given the
ongoing moisture advection into the western Great Lakes, a mention
of light showers will be carried in the TAFs through Mon morning at
this time.

D21/DTW Convection...The presence of instability aloft tonight will
support a low chance (<30 percent) of convection across the airspace.

.DTW THRESHOLD PROBABILITIES...

* Low in thunderstorms tonight.

&&

.PREV DISCUSSION...
Issued at 307 PM EDT Sun Aug 30 2026

DISCUSSION...

A moist airmass is in place over Lower Michigan, as both 12z DTX/APX
RAOBS came in with a 5 C dew pt at 700 MB. Waves of isentropic
ascent have been supportive of widespread showers. Fortunately,
instability is limited, and rainfall amounts have been manageable,
generally in the range of a quarter of an inch (south) to one inch
(north).

An upper level ridge/heat dome over the central Plains will drift
northeast, reaching southern Illinois by Monday evening. The
extension of the ridge axis over the northern Mississippi River
Valley will subsequently move overhead into the central Great Lakes
on Monday as well. High temperatures will be dependent on how well
the warm front and tonight`s expected showers and thunderstorms
clear southeast Michigan Monday morning. The north half of the CWA
is favored location, as local probabilistic guidance suggests pops
aoa 70 percent north of M-46.

With 850 MB temps progged to rise into the 20-21 C range Monday-
Wednesday, max temp potential is certainly aoa 90. However, much
like today, any thick cloud cover and shower/thunder activity during
the day could short-circuit max temps. In addition, the outgoing NBM
surface dew pts appear to be too high (widespread lower 70s), so
advertised heat indices appear too high as well.

The upper-level ridge is already flattened on Tuesday over Lower
Michigan, with westerly flow in place as 500 MB low tracks through
northern Ontario. At least moderate instability building up in a
weakly capped environment suggests that there will be some diurnal
activity, especially with any enhanced low level convergence/lake
breeze/marine influence. Sufficient bulk shear to support a chance
of severe storms, if in fact storms do go up.

A slight drying out of the deeper moisture in place as we head into
Wednesday could support the warmest maxes of the week, per the NBM.
Still, confidence is not high, as height falls arrive by Wednesday
evening/night and a potentially active baroclinic/frontal zone
develops over southern Lower Michigan into Thursday.

MARINE...

Several days of unsettled weather as a primary low pressure system
over central Canada and secondary low over the northern Plains send
a series of fronts across the region. Periodic showers and
thunderstorms will accompany the fronts while the slightly cooler air
over the waters brings chances of waterspouts with the storms over
the lakes. Winds will largely be from the south today with max gusts
around 20 knots. Winds turn more southeasterly on Monday while
remaining mostly below 20 knots before turning westerly on Tuesday.

HYDROLOGY...

Renewed shower development and possible thunderstorms are expected
tonight into Monday morning, mainly north of the I-69 corridor. With
today`s heaviest rainfall falling along M-46 priming the ground,
even a low chance scenario of rainfall totals exceed 1 inch late
tonight into Monday morning could cause localized minor flooding of
roads, poor-drainage areas and rises in local rivers. The chance for
additional showers and thunderstorms lingers Monday into Tuesday.
Any isolated to scattered storms on Tuesday could become intense and
produce torrential rainfall, leading to localized flooding in poor
drainage areas as well.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

AVIATION.....SC
DISCUSSION...SF
MARINE.......DRK
HYDROLOGY....SF


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