385
FXUS63 KDTX 271123
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
723 AM EDT Fri Jun 27 2025

.KEY MESSAGES...

- Thunderstorms are likely this afternoon and evening with a Slight
Risk of severe weather between 4 PM and 9 PM.

- The primary hazards are damaging wind gusts in excess of 60 mph
and torrential downpours.

- Temperatures cool into the mid 80s Saturday before climbing back
toward 90 degrees Sunday and Monday

- Another cold front brings chances for showers and thunderstorms on
Monday.

&&

.AVIATION...

Moist antecedent conditions this morning has resulted in LIFR to IFR
conditions in low ceilings and fog this morning for the Detroit taf
sites. Conditions are expected to improve the first hour of the
forecast period. Upper level jet forcing and a wave of surface low
pressure will then bring numerous showers and thunderstorms today.
Most likely timeframe for strong to severe thunderstorm activity is
between 21-01Z. Southwest winds of 20 to 25 knots this afternoon.
MVFR ceilings in stratus is expected to develop over the region this
evening.

For DTW/D21 Convection... Thunderstorm potential between 18z and 22z
Friday.

 THRESHOLD PROBABILITIES...

* Moderate for thunderstorms Friday afternoon.

* Moderate in ceilings aob 5000 feet this afternoon. High tonight.

&&

.PREV DISCUSSION...
Issued at 436 AM EDT Fri Jun 27 2025

DISCUSSION...

A line of decaying elevated thunderstorms is tracking across lower
Michigan this morning. Warming cloud top temperatures and decreased
lightning activity over the past several hours indicate the
weakening trend to this line, which will continue as it outpaces
existing MUCAPE. Considering it will take some time for hydrometeors
to completely evaporate, have increased PoPs substantially over the
western half of the CWA through mid-morning.

Humid conditions are already in place with most sites reporting
dewpoints in the low 70s. Nocturnal convection will only add to this
moisture to support primed boundary layer conditions for
destabilization early this afternoon ahead of a cold front. Nearly
all guidance brings high temperatures today to around 90 degrees,
fueling about 1500-2000 J/kg MLCAPE. While not overly impressed by
the hi-res models/HREF ensemble, there is a signal for a broken line
of storms to develop between roughly 4pm-9pm this evening. Although
shear profiles are modest (25-35 knots) and nearly parallel to storm
motion, do think the rich theta-e airmass and pockets of dry air
aloft will enhance downdrafts/cold pool development enough for
damaging wind gusts in excess of 60 mph on a more widespread basis
than what we have seen the past few days. Not expecting frequent rotation
with these storms provided mostly unidirectional shear profiles,
although a localized low end tornado risk does exist in the backed
flow regime of the marine layer. This is especially true around the
Thumb where 0-6km bulk shear is larger and in closer proximity to the
cyclonic circulation of the surface low. All of this is encompassed
within a Slight Risk for severe weather designated by SPC. The high
moisture airmass will also bring potential for flooding, as discussed
in the Hydrology section.

The cold front successfully clears out the 70+ degree dewpoints into
the Ohio Valley by Saturday morning, setting up a seasonable day
across SE Michigan with high temperatures holding in the mid-80s.
Strong subsidence takes hold and will maintain a capping inversion
throughout the weekend to limit surface-based thunderstorm chances.
The presence of a mid-level anticyclonic circulation in the 850-
700mb wind fields confirms the stable environment aloft. By Sunday,
temperatures warm back toward the low 90s as the strong SE CONUS
ridge makes its final push into lower Michigan. These warm
temperatures and eventual moisture transport on Monday briefly bring
warm and muggy conditions to SE Michigan. This airmass however will
be short-lived as another cold front tracks through the region
Monday night-Tuesday morning. The front itself will be the focus for
additional thunderstorm chances, while the post-frontal airmass
affords more seasonable conditions and a drier Canadian airmass. For
reference, all three LREF ensemble mean PWATs are below 1.0 inch
Tuesday-Wednesday of next week.

MARINE...

Another round of strong thunderstorms develops today as low
pressure, and associated cold front tracks through the Central Great
Lakes late in the day. Outside of thunderstorms, southwest winds
look to remain below 20 knots.  Light wind and favorable weather
follows the passage of the cold front, with weak high pressure
Saturday followed by another low pressure system entering the
northern Great Lakes during Sunday through Sunday night. This system
brings a stronger cold front into Lake Huron and Lower Michigan to
start next week.

HYDROLOGY...

A cold front tracks across SE Michigan this evening, bringing a
broken line of thunderstorms through the region between roughly 4 PM
and 9 PM. These storms will occur in a warm and moisture-rich
airmass which will be favorable for rainfall rates to exceed 1 inch
per hour. Localized flooding will be possible, especially
considering the several inches of rain that has already fallen in
some spots this week. Typical urban, small stream, and flood prone
areas are most at risk but also any location that has experienced
repeated rounds of showers and thunderstorms.

&&

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

$$

AVIATION.....CB
DISCUSSION...MV
MARINE.......MV/SF
HYDROLOGY....MV


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