598
FXUS63 KDTX 291958
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
358 PM EDT Sat Aug 29 2026

.KEY MESSAGES...

- Pockets of light rain toward the Tri Cities this evening become
  scattered to numerous showers and thunderstorms late tonight and
  Sunday morning. Additional rounds of showers and thunderstorms
  continue Sunday afternoon into Monday.

- Severe storm intensity is not expected, however there is a chance
  for locally heavy rainfall mainly along and north of I-69 from late
  tonight through early Monday.

- The weather pattern supports warmer temperatures and increased
  humidity during the early to mid portion of next week, however with
  high temperatures strongly dependent on coverage and duration of
  lingering showers and thunderstorms.

&&

.DISCUSSION...

Another pleasant late August day under quickly thickening high clouds
is in progress for SE Mi as high pressure centered on the Atlantic
coast extends back into the Great Lakes. The high pressure air mass
has carried temperatures on the mild side with low humidity over the
last few days. This begins to change tonight as a broad area of low
pressure developing across the Plains increasingly becomes the
forecast concentration for the Great Lakes Sunday through the early
week period.

First up is the MCS decaying nearby upstream this afternoon and the
potential for remnants surviving into Lower Mi this evening,
followed by a new round of nocturnal convection later tonight.
Afternoon satellite and radar trends offer convincing evidence of
MCS dissipation, but also of a robust MCV produced as a result. This
wave is captured well by the range of deterministic models and is
projected to move into the area with a chance of carrying remnants
this far east or producing new scattered showers overhead this
evening. Model depictions of the mid level theta-e ridge indicate
slightly improved potential toward the Tri Cities and northern Thumb
followed by a period of subsidence trailing the MCV heading into the
post midnight hours. The Tri Cities and Thumb, down toward the I-69
corridor, is also the area favored for another round of
showers/storms that move in from the Midwest late tonight and Sunday
morning. This is convection forced by the low level jet more nearby
to the west compared to this morning, from WI into western Lower Mi,
which then follows the 850 mb theta-e ridge inbound ahead of the
system warm front into central and SE Mi. The convective signal is
convincing in both HREF/REFS ensemble mean QPF and in that from
deterministic runs as well due to the involvement of the larger
scale low pressure system. NBM rain probabilities are much improved
in this model cycle offering chance POPs this evening trending to
likely/numerous late tonight and categorical/widespread Sunday
morning north of metro Detroit. No concerns for severe intensity
given the considerable west to east instability gradient, however
there is a low chance of localized heavy rainfall in the west to
east alignment of convective development and downstream propagation.

The same is true for Sunday as low pressure moves toward the
SD/IA/MN border and the warm front extends eastward into southern
Lower Mi by Sunday afternoon. The position of the warm front
maintains cloudy conditions all areas and showers again having
greater coverage with northward extent from metro Detroit toward the
Tri Cities and northern Thumb. HREF and REFS mean SB and MU CAPE are
below 500 J/kg while mean PW approaches 2 inches through peak
heating, limiting convective potential to an additional chance for
locally heavy rain (see Hydro below) Sunday afternoon and Sunday
night.

There was a slight edge toward model solutions moving the warm front
into the northern Great Lakes for a lengthy period of time Monday
afternoon and Tuesday, allowing a new round of heat and humidity to
build into the region. Trends in today`s model cycle are less
favorable for full development of a warm sector into SE Mi during
this time. Instead, model solutions suggest a flatter mid/upper level
ridge and faster westerly flow aloft over the Great Lakes leading to
quick progression of surface low pressure and arrival of the
trailing cold front. This scenario both shortens the residence time
of any potential heat and humidity while increasing the chance for
clouds and additional showers/storms as the front stalls until
perhaps Wednesday.

&&

.MARINE...

High pressure has drifted eastward over much of the eastern seaboard
today as we now look west as the developing low pressure system and
associated fronts that will slowly move into the area. Leading warm
front will lift toward Lake Michigan today with increasing clouds
and rain chances tonight through Sunday. In addition, a cold front
will be drifting southward toward the northern Great Lakes adding to
the forcing which will drive precipitation chances. Winds will
largely be from the south today and Sunday with max gusts around 20
knots. Winds turn more southeasterly on Monday while remaining
mostly below 20 knots before turning westerly on Tuesday.

&&

.HYDROLOGY...

Forecast confidence is increasing on an active pattern of showers
and thunderstorms developing across central and southern Lower
Michigan from late tonight through the early week. The system
incorporates deep Gulf moisture into clusters of thunderstorms that
generally have greater coverage along and north of the I-69 corridor
where rainfall totals are expected to average 0.5 to 1 inch from
Sunday morning through Monday morning. There is a chance for locally
higher totals where thunderstorms occur repeatedly over a shorter
time period, however these location and time details are unclear at
this point in the forecast. This general pattern raises the chance
for localized flooding of roads and poor drainage areas from early
Sunday through early Monday. The chance for additional showers and
thunderstorms also lingers later Monday into Tuesday.

&&

.PREV DISCUSSION...
Issued at 1239 PM EDT Sat Aug 29 2026

AVIATION...

VFR conditions hold through the remainder of the daylight period, as
high based cloud thickens with time downstream of an area of
convection now lifting across Wisconsin. This moisture will lift
into lower Michigan this evening while gradually diminishing in
coverage and intensity. Expectation remains for simply a limited
probability for a few showers to survive, mainly at MBS, with little
consequence. Additional light shower development will remain
possible overnight, then with higher probability Sunday morning
again with higher probability at MBS/FNT. Warm front sets up over
the region Sunday, which may introduce the potential for a few
thunderstorms during the latter half of the day as instability
increases with daytime heating.

D21/DTW Convection...No convection is forecast through tonight.

DTW THRESHOLD PROBABILITIES...

* None.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.

&&

$$

DISCUSSION...BT
MARINE.......DRK
HYDROLOGY....BT
AVIATION.....MR


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