970
FXUS63 KDTX 131040
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
640 AM EDT Thu Aug 13 2026

.KEY MESSAGES...

- Mainly dry weather expected through Saturday with seasonably warm,
but humid, conditions.

- Showers and thunderstorms return late Saturday into Sunday.

&&

.AVIATION...

Moist near surface conditions again contributing to some areas of
very low stratus and fog development early this morning. Expectation
again for those areas witnessing LIFR to IFR conditions to see
steady improvement within the 13z-15z window as daytime heating
increases influence. Otherwise, generally drier and more stable
conditions will exist today and tonight, as the focus for convective
development holds to the south and west. Steady increase in high
based cloud expected with time today, with some degree of scattered
to broken diurnal VFR cu development. Winds will remain light with
some variability as weak high pressure drifts through.

D21/DTW Convection...No thunderstorms anticipated at DTW during the
forecast period.

.DTW THRESHOLD PROBABILITIES...

* High for ceiling 5000 feet or less this morning, then low this
  afternoon through tonight.

&&

.PREV DISCUSSION...
Issued at 400 AM EDT Thu Aug 13 2026

DISCUSSION...

Minimal adjustments to note regarding the synoptic pattern today as
broad ridging persists with quick northwest flow aloft. Geopotential
heights rise slightly over Southeast Michigan as the longwave axis
becomes reestablished further west, closer to The Rockies.
Positioned downstream of the apex, mid-level geopotential heights
over Lower Michigan appear largely unchanged, if not slightly
higher, while lower column subsidence offer confidence in mainly dry
conditions. As has been the case for most of the week, near surface
moisture remains pervasive, marked by dewpoints in 60s. Surface-
based instability faces a challenging unlock process warmer mid-
levels translate into poor lapse rates of less than 6 C/km. Latest
NWP solutions indicate meager MUCAPE on the order of 250-500 J/kg.
Weak CVA activated by perturbed flow aloft is not expected to
suffice in triggering any meaningful convection, although a few
isolated narrow-diameter showers cannot completely be ruled out,
especially with any favorable lake breeze interactions. As for the
fate of upstream MCS activity moving from The Plains into portions
of the Midwest, low-end potential exists for a glancing pass at the
southern portion of the CWA this evening or early tonight. Should
this materialize, it would mainly affect locations south of I-94 as
evidenced by the slower and more eastward trajectory of the 13.05Z
HRRR, compared to the 00Z run.

Low convective potential again Friday as flow weakens aloft and the
ridge gets flattened by a digging Canadian shortwave. Similar
temperature trend as 850 mb temperatures linger in the mid teens,
resulting in highs around the mid 80s. Surface high pressure over
Ontario will have a weak hold on gradient flow locally, becoming
northerly composed. Precipitation chances will be dictated by
upstream convective evolution, mainly along the same Ohio border
vicinity zone. A moist low-level jet approaches Saturday night along
a warm front leading to a sharp Theta-E surge as low pressure lifts
in from the southwest. Potential exists for organized convection
with the initial front, and again with a trailing cold front through
Sunday. Winds shift from south to northwest behind the front with a
brief reprieve in temperatures and dewpoints for Monday and Tuesday.

MARINE...

A stalled front near the southern Michigan border will continue to
be a focus for showers and thunderstorms as systems ripple along the
boundary. The next chance coming later tonight for Lake St Clair and
Lake Erie being closer to the stalled front.  Could see some storms
go up around the Thumb later this evening too as lake breeze
boundaries activate. Outside of any convection, high pressure to the
north of the front will provide generally light northwesterly winds
through tonight at 10 knots or less. With the lighter winds, there
are some weak signals for patchy dense fog over Lake Huron at times,
through confidence remains low. On Friday, the high pushes eastward
across the central and eastern Great Lakes which will favor an
uptick in northeast winds. Winds then turn southerly late Saturday
and increase to around 20 knots ahead of a cold front Saturday night.

&&

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

$$

AVIATION.....MR
DISCUSSION...KGK
MARINE.......DRK


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