687
FXUS63 KDTX 230336
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1136 PM EDT Fri Aug 22 2025

.KEY MESSAGES...

- Scattered showers and thunderstorms are possible Saturday
afternoon. Severe weather is not likely.

- Below normal temperatures Sunday through Wednesday with highs in
the upper 60s to 70s.

&&

.AVIATION...

Low level south-southwest flow is now developing across Se Mi as
high pressure sinks south of the state and weakens. There are
indications that this flow may drive some remnant moisture at or
above 4000 ft into Se Mi late tonight, which will potentially
support some cloud cover into daybreak. A cold front will traverse
Se Mi during peak daytime heating Sat aftn/evng. This front will
support a chance for convection. Weak forcing and a capping
inversion will limit the coverage of showers/thunderstorms along/in
advance of the front, suggesting just low probabilities at this
time.

For DTW/D21 Convection...Isolated to possibly scattered line(s) of
convection are forecast to move across the D21 airspace, mainly
between 19Z and 01Z Saturday afternoon/evening.

THRESHOLD PROBABILITIES...

* Low in thunderstorms Saturday afternoon and evening.

&&

.PREV DISCUSSION...
Issued at 344 PM EDT Fri Aug 22 2025

DISCUSSION...

Strong upper low working across central Canada today will continue
to help flatten the existing ridge in place across the region. The
surface high thats been over the state the last couple days has been
pushed southward keeping us on the northwest portion of the high
tonight. Any diurnal cu should dissipate rapidly this evening
leaving clear skies heading into tonight. The time of year and
recency bias suggests taking a look into fog potential, but thinking
southwesterly flow ahead of an approaching cold front will keep
winds up enough combined with elevated clouds expanding across SE MI
which will mitigate any real concern. Could still see some shallow
fog in the typical areas as dewpoints bottom out around 60 tonight.

The low passing through Ontario tomorrow will pull a cold front
through lower MI in the afternoon/evening bringing the next chance
of showers and thunderstorms. Initial prefrontal band along a theta
e gradient and weakening axis of vorticity slides through in the
morning with most guidance suggesting it to be mostly dry, or light
showers as the area is capped around 850-700mb with no instability
in the morning. Front itself arrives later in the day during the
heat of the day presenting a chance for storms across a portion of
the area. Upper level forcing is not great, surface convergence is
weak, little in the way of low level jet support with 20-30 knots
overhead and SBCAPE maxes out around 700 J/kg with effective shear
around 20-25 knots briefly late in the evening in a short few hour
window where soundings look to break the cap. So overall not the
best looking setup across the area. CAMs have been decreasing
coverage of storms through the day so capped us off with a chance
pop for the north in the morning with the initial moisture surge,
and along the eastern counties in the evening generally 20-00Z.
Severe weather is not anticipated based issues noted above, SPC
having us in General Thunderstorms, and no support from machine
learning.

The upper level trough the parks over the Great Lakes Sunday Tuesday
night bringing a much cooler airmass to the region as 850mb temps
drop to around 5-7C and 500mb temps fall to around -15 to -20C.
Highs will struggle to break 70 Monday and Tuesday with lows down
into the 40s. With periodic mid level waves tracking through the
trough, there will be some periods of light rain or drizzle possible
with lake enhancement. The core of the trough looks to eject to the
northeast Wednesday allowing the trough to start breaking down, but
will hold over the region to some degree through the end of the
week.

MARINE...

Ridge of high pressure starts to breakdown/dislodge tonight into
Saturday as low pressure systems track across west-central Ontario
and Lake Superior. This drags a cold front through the central Great
Lakes through the second half of Saturday, perhaps into the early
overnight hours. Expect some shower/storm development ahead of the
boundary, but models still differ on the degree of coverage. Cannot
rule out a couple strong to severe thunderstorms which may generate
locally higher winds/waves. Cooler conditions settle in behind the
front for Sunday and the first half of next week. This leads to
better mixing potential with gusts approaching Small Craft Advisory
wind conditions at times. Chances exist for shower and waterspout
development over portions of Lake Huron Monday and Tuesday.

&&

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

$$

AVIATION.....SC
DISCUSSION...DRK
MARINE.......KGK


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