099
FXUS63 KDTX 090645
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
245 AM EDT Sun Aug 9 2026

.KEY MESSAGES...

- Dry and seasonable conditions today.

- Chance of showers and thunderstorms this evening and overnight.
Isolated storms will be capable of producing damaging wind gusts and
hail. In addition, heavy rainfall will be possible.

- Seasonable temperatures with periodic chances for thunderstorms
throughout the early week period

&&

.DISCUSSION...

Ridge of high pressure anchored over the region early this morning
will maintain influence heading into Sunday as it slowly vacates to
the east. This provides a brief window for deeper layer stability to
exist within the background of prevailing lower amplitude mid level
west-northwest flow. This will support dry conditions with a high
degree of insolation potential through the afternoon hours. Emerging
low level southerly flow will initiate a modest period of warm air
advection through the daylight period. This will bring highs into
the middle and upper 80s, but with a more manageable humidity level
noted with a dewpoint generally hovering near 60 degrees.

Attention for the evening period turns to behavior of convective
activity now organizing over the upper Miss valley within a zone of
deeper moist/warm air advection and along one of several mid level
impulses embedded within the mean flow. Model guidance offers a
general consensus for this activity to maintain some form of
integrity as translates downstream today, reaching the local area
during the evening hours. Higher likelihood for this activity to
arrive in a weakening state as instability really diminishes with
eastward extent, perhaps even falling apart or becoming focused over
a smaller footprint. Forecast will scale precipitation chances down
into the chance to lower likely category for the 22z-04z window and
allow near term trends to dictate further revision. Greater moisture
advection occurs within the wake of this wave overnight, initiating
a secondary opportunity for convective expansion along the existing
frontal boundary/outflow extending across southern lower MI. While
there may be a tendency for greater expansion to build southward
into the deeper instability residing south of the state line, the
potential certainly exists for some clusters of marginally surface
based cells to work eastward into mainly areas south of I-96 during
the overnight hours. SPC continues to highlight this corridor for an
isolated risk of damaging winds and hail. In addition, potential for
some training of cells along the boundary will offer the possibility
for areas of heavier rainfall and a localized flash flooding threat.

Forecast for Monday carries strong dependence on behavior of the
overnight activity both locally and upstream. There is currently
strong evidence across the model spectrum that the more meaningful
forced ascent and deeper instability will generally remain to the
south and west during the day. There remains at least a lower
probability for mainly southern sections to be vulnerable for
renewed diurnal development should more tangible forced ascent
materialize. Latest NBM corroborates this noted trend with a sizable
downward revision in forecast precip chances for the Monday period.
This casts considerable doubt on prospective severe convective
chances. There perhaps is greater potential for another round of
convective expansion Monday night into Tuesday over the northern
Ohio valley, which could spill into southern lower Mi as bouts of
greater moist/warm air advection occur along the oscillating
boundary and within any passing shortwave. In a nutshell, the early
week precip forecast carries very low predictability and likely will
require additional revision. Temperatures during this period will
remain seasonable for mid August.

&&

.MARINE...

High pressure slides east across the region tonight into Sunday,
with west-northwest winds becoming south and southwest by Sunday
morning. South winds increase Sunday across northern Lake Huron, to
around 20-25 knots. The uptick in winds on Sunday over the Saginaw
Bay will bring 2-3 feet waves, but conditions look to fall just
short of small craft advisory criteria at this time. Much of Sunday
remains dry, but Sunday evening through early next week an active
pattern will bring back chances for organized thunderstorms as a
slow moving frontal boundary sets up across the southern Great Lakes
region and lingers through mid week. By the end of the week, high
pressure builds south from central Canada.

&&

.HYDROLOGY...

One or more rounds of thunderstorms will track toward the region
this evening and overnight. Low confidence exists on possible
trajectory, duration and coverage of any activity, with greater
overall potential perhaps developing mainly south and west of the
area. If thunderstorms do impact SE Michigan, there will be
potential for training thunderstorms capable of rainfall rates in
excess of an inch per hour. Localized flash flooding will be
possible, especially if heavy rainfall impacts urban areas.

&&

.PREV DISCUSSION...
Issued at 1140 PM EDT Sat Aug 8 2026

AVIATION...

High pressure promotes clearing skies and weakening winds through
tonight. Influence of said high lingers through Sunday morning
before upstream convection over the western Great Lakes approaches
the area in the evening. Exactly how well this complex survives into
SE MI, or the degree of redevelopment overnight behind it, carries a
good amount of uncertainty at this stage so continue to hold Prob30
mentions.

D21/DTW Convection... No convection forecast through Sunday
afternoon. Upstream storms over the western Great Lakes are expected
to track near/over SE MI Sunday evening/night though this carries a
high amount of uncertainty this far out.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling aob 5000 ft through Sunday afternoon.

* Low for thunderstorms Sunday evening.


&&

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

$$

DISCUSSION...MR
MARINE.......JA
HYDROLOGY....MR
AVIATION.....KDK

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at www.weather.gov/detroit.