021
FXUS63 KDTX 040849
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
449 AM EDT Mon Aug 4 2025

.KEY MESSAGES...

- Temperatures gradually moderate to above normal throughout
mid week. By late week, very warm and humid conditions return.

- Hazy skies remain likely today due to Canadian wildfire smoke.

- Mostly dry weather anticipated through the end of the week. More
uncertainty of rain chance timing next weekend.

&&

.AVIATION...

Canadian wildfire smoke continues to result in intermittent
reduction of visibility into the 3 to 6 mile range this morning.
Some improvement in visibility will be likely through the daylight
hours with some return chances for mvfr visibilities later this
evening and overnight. Otherwise, dry conditions continue under high
pressure.

For DTW/D21 Convection...No thunderstorms will occur
through the duration of the TAF period.

THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 324 AM EDT Mon Aug 4 2025

DISCUSSION...

Little change in the synoptic pattern is anticipated over Lower
Michigan today as both weak surface and H5 ridging stalls over the
region. Largely a persistence forecast for today across the cwa with
perhaps temperatures a couple of degrees warmer due to another day
of airmass modification. Plan view of thermal progs largely support
little warm air/thetae advection with a continued easterly fetch.
Stagnant pattern with HRRR-Smoke guidance supports continued smoke
haze today and tonight. The one item to monitor is the very low
potential for a shower to the north of Saginaw Bay. There is some
weak model signal/agreement in some grid scale convective
development. Given flow direction this appears to miss the forecast
area as it will require orographic effects and upsloping.

Weakness in the height field in a very weak Rex Block type feature
will allow deeper midlevel moisture to coalesce over the Ohio and
Tennessee River Valleys early this week. Models suggest that a very
weak cyclonic circulation and better 850-600mb thetae advection will
lift northward and clip portions of Southeast Michigan late Tuesday
and Tuesday night. Not a very strong signal, but there will be at
least a very low chance (less than 15%) for a pop-up shower after
20Z Tuesday. Very low confidence the preferred area for any shower
would be the I 69 corridor along a 700-500mb moisture gradient.

Arc of absolute vorticity is forecasted to push across Southeast
Michigan Wednesday. Interesting to note that while a period of
differential vorticity advection will occur, the model data shows a
quick regeneration of strong anticyclonic influence over the
forecast area for later Wednesday and Thursday. Forecast soundings
support restrengthening of subsidence and midlevel static stability in
the 7.0 to 15.0 kft agl layer. Southwesterlies and amplifying ridge
overhead brings a solid uptick in temperatures Thursday and Friday.
Highs in the upper 80s to 90 degrees some 5 to 10 degrees above
normal.

Question for next weekend will be the evolution of the ridge and
exactly when geopotential heights within the ridge are suppressed.
The going forecast is hot with heat indices near 90 and dry
conditions.

MARINE...

Quiet weather continues through mid week as a new area of high
pressure starts to build into the region out of the north. The
center of the high now positioned to the north will bring about
easterly flow today but still below 10 knots. Could see a slight
increase in northeasterly winds Tuesday with gusts into the teens,
mainly along the Lake Huron shoreline.

&&

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

$$

AVIATION.....AM
DISCUSSION...CB
MARINE.......DRK


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