076
FXUS63 KDTX 251032
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
632 AM EDT Fri Jul 25 2025

.KEY MESSAGES...

- Still on the warm, muggy side today with lingering chances for
showers and non-severe thunderstorms towards the southern Michigan
border.

- Additional rounds of showers and thunderstorms are likely for
Saturday and Saturday night. A few storms could be strong to severe.
Torrential rainfall and localized flooding possible under any storm.

- Hot, humid weather redevelops Sunday into the first part of next
work week.

&&

.AVIATION...

Satellite and radar suggest an ongoing decrease in the intensity and
coverage of the convection across far northern Indiana. A subtle mid
level short wave along the instability gradient is supporting this
convective response. While the bulk of lingering thunderstorms is
expected to pass south of metro Detroit early this morning, some
residual showers may continue to affect portions of metro Detroit.
Farther north, shallow and weak cold air advection along a
stationary front has allowed some MVFR based clouds and a few
patches of fog/IFR clouds to develop, mainly from FNT to MBS.
Diurnal mixing will lift the cloud based by afternoon in this
region. Building afternoon instability generally south of FNT will
support a another chance for late afternoon/evening convection.

For DTW/D21 Convection... Although some degree of weakening is
expected, radar trends suggest ongoing northern Indiana convection
will impact the southern portions of the airspace early this
morning.

THRESHOLD PROBABILITIES...

* Moderate in ceilings aob 5000 today. Low tonight.

* Low in thunderstorms today and tonight.

&&

.PREV DISCUSSION...
Issued at 305 AM EDT Fri Jul 25 2025

DISCUSSION...

A weak cold front is in the process of gradually sinking south early
this morning, however with the parent low racing east over Quebec,
driving mid-level flow turns parallel to the boundary. This allows
the front to stall out over the southernmost portions of the area by
mid to late morning. Some disagreement in CAMs in the exact position
but roughly between I-94 and the OH border is favored. With
additional ribbons of vorticity riding out of the Midwest along this
boundary, isolated to scattered shower/non-severe storm chances
linger through the day for areas along/south of M-59. While the
front shunts the hottest/humidest air to our south, the airmass is
only minimally changed as highs still top out in the mid 80s with
dewpoints slowly falling below 70F for the northern half of the
region. Southern areas look to keep the lower 70s/around 70
dewpoints through the day owing to the nearby lingering front.

Said front lifts back north daytime Saturday in response a weak
shortwave ejecting out of the central Plains. Increasing cloud cover
(and rain chances) aid in keeping highs confined in the 80s behind
the warm front though >70F dewpoints also make their return as an
anomalously moist airmass advects into the Great Lakes. PWAT`s
increase over 2" with the more bullish models suggesting up to
around 2.25" by afternoon (well over the daily climatological maxima
of just over 2"). Forecast soundings show warm cloud layers around
13kft further supporting a heavy rain/flooding threat with any
convection. Nearly all CAM solutions advertise decaying convective
remnants reaching the southern Great Lakes by morning though how
this activity then progresses for the rest of Saturday is unclear at
this point. Solutions like the HRRR and NAM 3km suggest it all but
dies before diurnal heating builds enough instability to generate
afternoon-evening convection. Conversely, solutions like the ARW and
HRDPS maintain these remnants with diurnal re-invigoration latter
half of the day. Regardless of outcome camp, sounding wind profiles
are dominated by largely unidirectional speed shear with greatest
values (30-35kts) focused over the southern half of the CWA- lesser
values (20-30kts) for the northern half, favoring multicellular
storm modes. As such, a few strong to severe storms (both wind and
hail hazards) can`t be ruled out with greatest potential the further
south you are. Areas south of I-69 remain under a Day 2 marginal
risk from SPC.

Weak surface high pressure establishes itself Sunday as broad
mid/upper ridging develops across the CONUS east of the Rockies.
This ridge governs the pattern for most of next week with SE MI
residing on its northern edge. While a multi-day period of hot,
humid weather is favored under the ridge, our positioning on the
edge offers chances for ridge-riding shortwaves and subsequent
convection to clip the area lowering overall confidence in the long
range forecast.

MARINE...

Cold front currently draped across central Lake Huron sinks south
through the morning before stalling between roughly Lake St Clair
and Erie setting up northerly flow for the bulk of the region. This
confines lingering storm chances to the southern Great Lakes today-
severe storms are not expected. Low pressure ejecting out of the
central Plains towards the Great Lakes causes this front to lift
back north as a warm front re-establishing southerly flow Saturday,
though still on the lighter side (less than 15kts). This draws
hotter, humid air back over the region fueling shower and storm
chances particularly Sat afternoon-evening. A few severe storms
(both wind and hail hazards) are possible towards the southern Great
Lakes. Weak surface high pressure than becomes established Sunday.

HYDROLOGY...

Isolated to scattered showers and storms linger towards the Ohio
border today where a cold front is expected to stall out. While
coverage is limited, locally heavy rainfall is likely under any
storm given the still humid airmass south of the front where PW
values hover just under 2". This front lifts back north Saturday as
warm front ushering in hot, humid conditions again. Anomalously
moist airmass overspreads the region with PWAT`s over 2" in addition
to warm cloud depths supporting efficient rainfall rates. A system
ejecting out of the Plains over the Great Lakes generates at least
scattered showers and storms focused in the afternoon-evening
Saturday (uncertainty still exists in the exact coverage of
storms). Rainfall rates in excess of 2"/hr would be possible under
any of these storms leading to areas of minor flooding especially in
low lying/flood prone areas. More impactful flooding is possible
should storms train over the same locations.

&&

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

$$

AVIATION.....SC
DISCUSSION...KDK
MARINE.......KDK
HYDROLOGY....KDK


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