217
FXUS63 KDTX 160741
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
341 AM EDT Thu Jul 16 2026

.KEY MESSAGES...

- EGLE has declared an Air Quality Alert today due to Canadian
  wildfire smoke reaching the surface and the resultant rise in
  PM2.5.

- Increasing chances for showers and thunderstorms Friday through
the weekend.

&&

.DISCUSSION...

Surface air quality observations and reduced METAR visibilities
confirm the substantial wildfire smoke plume is fully entrenched
across SE MI. Persistent northwest flow with flow trajectories
extending to the Ontario wildfires will maintain a steady supply of
smoke and provide little opportunity for meaningful improvement per
HRRR-smoke model. Persistent smoke cover will introduce considerable
uncertainty into the high-temperature forecast given attenuation of
shortwave radiation through scattering and absorption leading to
suppressed boundary layer growth. As such, have tempered temperature
values down relative to statistical guidance, attempting to align
where modeled vertically integrated smoke is maximized. But overall
there is little precedence and limited guidance for smoke of this
density and persistence. Highs have therefore been capped to 90
closer to the MI/OH border and urban metro region and hold in the
80s for locations north. Outside of smoke/haze, dry weather prevails
under diffuse high pressure.

Lingering haze/smoke holds into Friday but wind direction will flip
to the south as high pressure washes out across the continental
northeast. This will attempt to work some of the haze/smoke out of
the region but overall gradient flow will be weak so this initially
will not be very efficient. This will usher in better moisture and
will bring the chance for showers and storms late Friday into
Saturday morning along the moisture/theta-e gradient as it initially
expands across SW michigan. A low pressure system that will move
across southern Ontario/Quebec and associated cold front that in
turn pushes across the Great Lakes will then bring likely chances
for showers and thunderstorms on Saturday. Projected favorable
afternoon or evening alignment of frontal passage could bring the
possibility for strong or severe storms noting ensemble mean values
of CAPE around 2000 J/kg and bulk shear values around 30 knots.
Passage of the front will bring relief from the hotter than normal
and humid conditions. Forecasted highs hold in the low to mid 80s
in the wake of the front through the midweek period.

&&

.MARINE...

Dense smoke due to Canadian wildfires has spread southward across
the entire central Great Lakes, in the wake of a backdoor cold front
last evening. The Dense Smoke Advisory has been expanded to all
waterways until 10 AM but an extension to later times will be likely. High
pressure builds back across the central Great Lakes today as north-
northwest winds hold this afternoon at or below 20 knots. The higher
values should be focused over the northern half of Lake Huron where
the pressure gradient is more constricted. Weak low pressures systems
emerge over the northern Plains and Mid- Mississippi Valley tonight,
eventually converging over the Great Lakes with time on Friday. This
leads to a more active period of showers and thunderstorms.
Prevailing winds should generally remain below headline criteria
through the forecast period, with one exception being marginal Small
Craft Advisory gusts over Saginaw Bay and/or The Thumb nearshores
Saturday afternoon. This arises within the wake of a cold front from
a secondary, and more robust, low pressure system passing through The
Straits.

&&

.PREV DISCUSSION...
Issued at 1140 PM EDT Wed Jul 15 2026

AVIATION...

Dense near surface smoke infiltrated the TAF sites this evening
immediately following the passage of the surface front. Visibilities
within the smoke have ranged from a half mile to two miles. Given
the strong boundary layer stability during the night, the TAFs will
maintain IFR prevailing conditions. Diurnal heating on Thursday
will offer the potential for more mixing and will thus warrant
prevailing MVFR during the daytime.

D21/DTW Convection...The risk of convection has ended as more stable
air slowly expands across the area.

DTW THRESHOLD PROBABILITIES...

* Medium for ceiling/vertical visibility at or below 5000 feet
  tonight and Thursday.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Dense Smoke Advisory until 10 AM EDT this morning for LHZ361>363-
     421-422-441>443-462>464.

Lake St Clair...Dense Smoke Advisory until 10 AM EDT this morning for LCZ460.

Michigan waters of Lake Erie...Dense Smoke Advisory until 10 AM EDT this morning for LEZ444.

&&

$$

DISCUSSION...AM
MARINE.......KGK
AVIATION.....SC


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