405
FXUS63 KDTX 302239
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
639 PM EDT Thu Jul 30 2026

.KEY MESSAGES...

- Multiple rounds of showers and a few embedded thunderstorms are
forecast Saturday and Sunday. There is considerable uncertainty in
the rainfall forecast, especially Saturday night and Sunday. There
is a low chance (10-20% chance) that a narrow axis of heavy rain
could develop and bring flooding concerns, especially over urban
areas.

- Dry weather returns early next week with warming temperatures
approaching 90 degrees by mid week.

&&

.AVIATION...

Dry and stable low level conditions held within the backdrop of low
to mid level ridging will maintain VFR conditions through Friday.
Some pockets of higher based cloud within the 6-9k ft layer will
tend to develop at times tonight. Winds turning light and generally
variable through the overnight period. Standard VFR diurnal cumulus
development expected with daytime heating Friday. Cirrus thickens
with time Friday afternoon and evening ahead of a low pressure
system forecast to enter the region this weekend.

D21/DTW Convection...No thunderstorms forecast through Friday
evening.

.DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 311 PM EDT Thu Jul 30 2026

DISCUSSION...

The rest of this evening is expected to remain mostly dry. Current
satellite and observational trends show the lake breeze boundary
make its way inland from the Saginaw Bay and southern half of Lake
Huron. There is a low chance (<15%) for a rogue shower to develop
along the lake breeze boundary through the evening hours.

The area of high pressure which has brought a bout of nice weather
over these last few days will gradually weaken and move over the Mid-
Atlantic region Friday through Saturday, in response to an
approaching and deepening longwave trough moving in from the
west. This change from large scale subsidence to what looks to
be multiple rounds of ascent moving into the region will transition
our weather pattern to a more active one for this weekend. Friday
will be a transition day where we will see an uptick in cloud cover,
but most of the day should remain dry.

The forecast for Friday night through Sunday will hinge heavily on
how a slow-moving upper level trough, the parent surface low
track across the Midwest, and whether or not this upper level wave
phases with another lobe of energy digging south into the region on
Sunday. Chances for precipitation for Saturday and now Sunday have
increased with this forecast package update, but this is still
considerable uncertainty in the weekend forecast.

Most ensemble members show a considerable increase in PWATs ahead of
the main upper level wave as moisture and warm air advection track
into the region and wrap back around the surface low, progged to
track across Illinois and Indiana. If this track holds true, then we
will be in a moisture-rich environment supportive of heavy rain, with
multiple rounds of large-scale ascent and an increased risk for
episodes of training convection. The drier solutions feature a
more open trough and a surface low that is considerably further
south. This uncertainty leaves a wide range of possible outcomes for
rain and possible impacts across southeast Michigan. If the higher
end rainfall solutions come to fruition, flooding may become a
concern in urban areas, especially Saturday night and possibly
Sunday.

By Monday, high pressure should settle back into the region as large-
scale subsidence takes over and a narrow, yet amplified upper level
ridge moves into the region. This will favor a warming and drying
trend into early next week.

MARINE...

Light and variable winds across the central Great Lakes this
afternoon as high pressure tracks through the region passing just to
the south across the Ohio River Valley into tomorrow. Wind fields
will respond accordingly and become southerly to westerly. A low
pressure system will then follows and also tracks across the Ohio
Valley over the weekend. Winds turn northeasterly across Lake Huron
Saturday night, which will bring favorable flow that will lead to
increased winds and waves through Saginaw Bay. This low and
associated frontal features will bring a chance of showers and
thunderstorms starting late Friday night and into Sunday.

&&

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

$$

AVIATION.....MR
DISCUSSION...JA
MARINE.......AA

You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.