179
FXUS63 KDTX 261725
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
125 PM EDT Thu Jun 26 2025

.KEY MESSAGES...

- Scattered to numerous thunderstorms again this afternoon as warm
and humid air builds back into Lower Michigan.

- There is a Marginal Risk of severe weather as storms may produce
damaging down burst winds. Localized flooding will also be possible
due to very moist airmass and saturated soils from recent storms
this week.

- A chance of thunderstorms continues Friday into the weekend as an
active pattern holds across the Great Lakes.

- High temperatures increase back to the upper 80s to 90 degrees
today through the weekend with heat indices up into the mid to upper
90s at times.

&&

.AVIATION...

Moderately unstable, uncapped environment over southeast Michigan,
with frontal boundary/dew pt gradient near the I-69 corridor.
Disorganized strong thunderstorms should continue, but location is a
bit challenging as outflow boundaries serve to focus additional
redevelopment.  None-the-less, multiple rounds of showers/storms
across southern TAF sites looks reasonable, and will be maintaining
the tempo TS group through the afternoon, although concerned with
the latest drift to the south with the bulk of the activity.
As low pressure enters the Western Great Lakes this evening, the
surface boundary over Lower Michigan will attempt to lift north,
providing better focus over MBS/FNT for the evening hours. With the
elevated low level moisture/high surface dew pts over southeast
Michigan tonight, much better chance for low clouds and/or some fog,
depending on how thick mid/high clouds from upstream activity over
the Western Great Lakes advances east. However, with today`s
rainfall, enough confidence in MVFR stratus and/or fog development to
include in tafs, with very light southerly winds tonight, IFR not
out of the question, especially at MBS. Another round of showers and
thunderstorms appears likely tomorrow afternoon as cold front
arrives during peak heating. Southwest wind gusts ahead of the front
will likely reach into the 20-25 knot range in the afternoon, in
addition to the stronger/gustier winds in any thunderstorm.

For DTW/D21 Convection...Bulk of storms over southern Lower Michigan
are showing signs of prograging southeast, away from terminal. Thus
lower confidence for the rest of the afternoon. None-the-less, would
expect enough destablization to trigger addtional storms late this
afternoon, and will keep much of the inherited taf intact.

 THRESHOLD PROBABILITIES...

* Low to medium for thunderstorms this afternoon and evening.

* Low in ceilings aob 5000 feet through evening. Moderate overnight
  and tomorrow afternoon.

&&

.PREV DISCUSSION...
Issued at 331 AM EDT Thu Jun 26 2025

DISCUSSION...

We remain on the northwestern edge of the large ridge across much of
the SE conus today. The ridge is slowly weakening though still
remains around 590 dam. This ridge continues to steer a very moist
airmass up through the Plains and across lower MI with PWATs still
hovering around 1.75 to 2+ inches which will carry through the end
of the week. Surface dewpoints took a hit across much of the area
when the cold front dropped through Tuesday, but remain around 70
across the far south and 60s for the rest of the area. This has lead
to showers/storms being very efficient rain makers the last couple
days with the uncapped, high CAPE, low shear environment with a few
areas developing localized flooding. This will remain a main concern
through the end of the week until Friday when a stronger system
passes through the Great Lakes and pushes the moisture south. We
remain in a Marginal Risk of Excessive Rainfall for both days to end
the week.

Will be hard pressed to remove chances of showers/storms during any
period through Friday as the persistent frontal boundary will
continue to meander about the region with the slightest ripple in
along the elevated front producing showers. The main difference
between today/Friday vs the previous two days of convection though
will be that we`ll have some more notable synoptic waves tracking
through the region through this main moisture axis bringing a couple
periods of more targeted pops.

The first wave is ongoing at press time, traveling through northern
MI and pulling the 850mb front back up through the area with
convection already firing along it over GRR. The surface front will
also get drawn northward this morning building north and east with
time allowing more unstable air (MUCAPE >2000 J/kg) back into a
larger portion of the CWA. Will keep chance pops at least through
the day with another period of scattered to numerous storms expected
with peak heating and the main instability gradient in the vicinity
of I-69. Localized flood risk with these storms along with wind
threat from precip loaded downbursts. Some small hail will be
possible with some storms. The second wave will again track through
northern MI Friday pulling the warm frontal surface farther north
through the whole CWA early in the morning with a chance of
convection firing along it as we get a bit more of the 850mb low
level jet (25-30 knots) over the area helping provide a bit better
forcing locally. We`ll be warm sectored most of the day allowing for
another unstable day with CAPE >2000 J/kg, but the warm sector will
provide a little cap to deal with. The cold front will get pulled
into the area in the afternoon/evening bringing another round of
more widespread convection.

Temperatures will make a run at 90 for our southern portion of the
CWA the next two days and when combined with the low-mid 70
dewpoints may result in heat indices in the mid to upper 90s,
possible touching 100 for a short period. With the expected cloud
cover and scattered convection, we will hold off on any heat
advisories at this time.

MARINE...

Warm front has lifted north into northern Lower Michigan this
morning, leading to stronger (25+ knots) easterly winds over the
northern Lake Huron. A wave of low pressure coming out of the Midwest
will trigger numerous strong to possibly severe thunderstorms.
Another round of strong storms on Friday before the low exits east.
Light northwest flow follows the low for Friday night into Saturday
before winds become light southerly for the second half of the
weekend with mainly dry conditions.

HYDROLOGY...

A front wavering north and south across Lower Mi will be focus for
showers and thunderstorms today through Friday, and possibly through
the weekend. Showers and storms area ongoing this morning as the
front moves back northward. The front becomes the focus for yet
another round of storms in the afternoon which spread across the
area in warm and humid air returning to the region. All of this
occurs in a deep/high moisture environment that promotes heavy
rainfall rates that could lead to localized flooding. Typical urban,
small stream, and flood prone areas are most at risk but also any
location that experiences repeated rounds of showers and
thunderstorms, which could happen anywhere across SE Michigan during
the mid to late week period.

&&

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

$$

AVIATION.....SF
DISCUSSION...DRK
MARINE.......SF
HYDROLOGY....DRK


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