007
FXUS63 KDTX 111849
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
249 PM EDT Mon Aug 11 2025

.KEY MESSAGES...

- Hot and muggy conditions continue through Tuesday with highs in
the low 90s and heating indices in the mid-90s.

- Potential for showers and non-severe thunderstorms from mid
afternoon into the evening hours today.

- Wider spread showers and thunderstorms again possible Tuesday,
with the potential for heavy rainfall.

- High pressure brings near normal temperatures and less humid
conditions to close out the work week.

&&

.DISCUSSION...

Highly broken line of scattered showers has begun to develop early
this afternoon marking the lead edge of a richer theta-e plume being
advected into lower MI. With this line crossing during peak heating
and MLCAPE`s nearing 1000J/kg, expectation is for continuing
blossoming coverage as satellite and radar indicate multiple weak
convergence axises within this plume. While scattered thunderstorms
are likely, forecast soundings depict fairly skinny CAPE profiles
and weaker column wind fields greatly hampering more
robust/organized convection. Main hazard with any thunderstorm that
manages to form will be locally heavy rainfall given PW values
between 1.5-1.75" and slower storm motion.

Lingering showers taper off late this evening with the loss of
diurnal heating. The region remains under deep layer southwest flow
through the night however with CAM guidance keying in on a nocturnal
low level jet development late tonight. This jet brings a renewed
push of moisture transport and subsequent elevated instability into
SE MI supporting scattered elevated shower/storm redevelopment after
midnight into early morning. As for rain chances/coverage Tuesday,
lack of defined forcing leads to a more nebulous forecast,
particularly first half of the day. Forecast soundings still
advertise an uncapped environment atop surface dewpoints in the
lower 70s allowing SBCAPE values to reach or exceed 1000 J/kg by
roughly noon. Given this setup, it would seem probable for scattered
convective development to occur by late morning-early afternoon. As
for location given the free release, anywhere in SE MI would have a
shot. That said, with the parent trough sitting over Lake Superior,
Saginaw Valley-Thumb would be slightly more favored for wider spread
convection. Coverage expected to increase through the day both due
to diurnal destabilization and increasing mid-upper height falls as
the trough slides towards the Soo. Severe potential with any storm
Tuesday is low as winds hold aob 25kts through the column, though an
isolated water-loaded downburst can`t be ruled out. This weaker wind
field does however support slow storm motion, which in combination
with warm cloud depths >10kft and PWATs between 1.5-2", results in
localized heavy rain-flood threat. Shower and storm chances persist
through the night as the attendant cold front sags through southern
lower MI. This front eventually clears south by mid Wednesday
morning tapering off any lingering activity.

Thermal troughing follows for Thursday and Friday as 850mb temps
hold closer to 13-14C resulting in a brief return to normal mid-
August highs in the lower 80s. Additionally, dewpoints fall to
around 60F making it a more comfortable feel. Broad mid-level high
pressure centered over the Southeast then draws the hotter, humid
airmass over the Plains back into the central Great Lakes this
weekend. Heat indexes return to the mid 90s as highs return the
lower 90s and dewpoints approach 70F again.

&&

.MARINE...

Showers and thunderstorms have developed in the presence of a
surface trough that is draped across lower Michigan. These storms
are moving east at ~20 knots, and will track across the marine zones
this afternoon-early evening before waning with sunset. These storms
will be slow-moving and disorganized, but could produce isolated
gusts over 30 knots. Southwest flow ensures persistent warm and
unstable conditions with several waves of showers/storms possible
Tuesday afternoon-evening ahead of a cold front that tracks through
Tuesday night. The environment initially favors pulse/multicellular
storm mode that becomes more linear in nature as the cold front
approaches in the evening. Gusts over 34 knots and heavy rainfall
are the primary threats. Precipitation chances linger through
Wednesday morning before high pressure and upper level troughing
move overhead to establish a quieter and cooler pattern for the back
half of the week.

&&

.HYDROLOGY...

Multiple rounds of showers and thunderstorms are possible this
afternoon through Tuesday ahead of a cold front that tracks through
the area Tuesday night. Moisture rich conditions are characterized
by PWAT values up to 2 inches and dewpoints in the low 70s.
Scattered thunderstorm activity will be capable of producing heavy
rainfall with rates over an inch per hour this afternoon and
evening. This will be followed by multiple potential waves of
thunderstorms Tuesday through Wednesday morning, in which slow-
moving and/or training thunderstorms will be possible. Flash
flooding will be possible in urban and low-lying areas along with
rises in areas rivers.

&&

.PREV DISCUSSION...
Issued at 141 PM EDT Mon Aug 11 2025

AVIATION...

Relatively deep moisture between 850-500mb will wash back into
Southeast Michigan this afternoon as a mid-upper level ridge
structure builds from northern Ohio to Quebec. Difficulty exists in
forecasting precipitation/showers/thunder because of some lingering
dry air in the 2.5 to 4.5 kft agl layer and fractured/multiple
convergence axes. There is enough vertical continuity in thetae this
afternoon to include a TEMPO for -TSRA at all taf sites. Most
favorable timing is between 19-24Z. Cloud development at taf time
has been relatively shallow, limited to diurnal heating.

For DTW/D21 Convection... The potential exists for non severe
thunderstorms between 21-24Z. Very little confidence in any
lingering activity between 00-09z.

 THRESHOLD PROBABILITIES...

* Moderate for thundestorms this afternoon.


&&

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

$$

DISCUSSION...KDK
MARINE.......MV
HYDROLOGY....MR
AVIATION.....CB


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at www.weather.gov/detroit.