633
FXUS63 KDTX 251725
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
125 PM EDT Wed Jun 25 2025

.KEY MESSAGES...

- Chance of thunderstorms today across much of SE MI with the best
chance of stronger storms occuring near the Ohio border.

- There are chances of thunderstorms each day through the end of the
week as we remain in an active pattern.

- High temperatures will increase back to the upper 80s to 90
degrees Thursday through the weekend.

&&

.AVIATION...

A front is stalled along the MI/OH border this afternoon which keeps
the terminals on the cool side of the boundary, at least for today.
Monitoring the potential for convection later this afternoon and
evening as low ceilings scatter out, offering a renewed period of
instability and VFR conditions. Any thunderstorm activity that
develops will be isolated to scattered in nature, but does appear
more probable for the southern terminals. Introduced a PROB30 from
19Z to 23Z for DTW/DET/YIP to account for this threat with a MVFR
ceiling/visibility restriction. Outside of localized gust/downburst
enhancement attributed to convection, winds should stay rather weak
through the period, generally from the northeast. Mainly dry
tonight, outside of a stray shower or two, before the front lifts
north as a warm font Thursday yielding additional shower and
thunderstorm chances. Additionally, more activity may occur at
FNT/MBS ahead of inbound low pressure system featuring the approach
of an attendant cold front. Did add a PROB30 after 17Z Thursday for
additional thunder.

For DTW/D21 Convection...A 30 percent chance of thunderstorms exists
across southern half of the airspace for the rest of today,
therefore a PROB30 was included. Any thunderstorms that develop are
expected to remain more or less scattered in coverage. Additional
thunderstorms are possible Thursday.

 THRESHOLD PROBABILITIES...

* Low for thunderstorms today and tonight, then medium Thursday.

* Low in ceiling at or below 5000 feet today and tonight.

&&

.PREV DISCUSSION...
Issued at 1053 AM EDT Wed Jun 25 2025

UPDATE...

A hefty frontal zone lying across southern Lower Mi is the forecast
focus for today and this evening. Morning observations indicated
showers percolating within the mid level moisture axis but following
a gradual downward trend in coverage/intensity. This activity will
leave a substantial band of clouds still in place to reinforce the
surface front this afternoon, not that it needs any support with a
20 degree Td spread from the northern Thumb to the Ohio border. It
is shallow toward the surface and daytime heating is expected to
bring the wind shift back north toward the I-94 corridor this
afternoon. Scattered thunderstorms focus there south as surface
based CAPE builds toward 1500 J/kg along the Ohio border, on the
northern fringe of the Ohio valley instability axis. The wind
profile ends up being the primary limiting factor as bulk shear is
projected to hold at or below 30 kts. The resulting pulse to
multicell storm mode poses a precip loaded downburst hazard and
locally heavy rainfall is likely given PW hovering near 2 inches as
shown in the 12Z DTX sounding. Initial development along the front
and south end of the cloud line is then favored to develop south of
the Ohio border, toward the instability axis, during late afternoon
and this evening.

PREV DISCUSSION...
Issued at 338 AM EDT Wed Jun 25 2025

DISCUSSION...

The surface front has pushed south of the state line but the
elevated frontal slope remains over SE MI keeping a very moist
airmass in place atop the shallow stable layer resultant from the
northeasterly flow behind the front. The 700mb front remains active
as of 07Z north of I-69 feeding off the last of the elevated
instability and likely fueled by the last bit of the 850-700mb jet
feature folding through the area to the south. Frontal slope stalls
today as it runs up against the strong ridging to the south, still
around 595 dam at 500mb.

Today we`ll remain under the elevated front with the solid ribbon of
PWATs across the area just under 2 inches. Surface dewpoints will
take a hit across the north with drier northeasterly flow, back down
into the 60s, but 70s will remain south of about M59. Elevated
instability will be much less today across most of the region,
likely less than 500 J/kg of MUCAPE up in the mid levels of the
atmosphere, but the surface front looks to waver a bit around the
state line with potential for a drift back northward which opens the
door for CAPE in excess of 1000 J/kg to build today south of I94.
Shear will be weak at 20 knots or less which really hinders the
chances for severe convection today. With the plume of moisture and
potential for weak little waves to ripple along the mid level front,
chances of thunderstorms will exist through the day with the highest
focus across the south. SPC pulled back the Marginal Risk area to
only Lenawee and Monroe which is where we`d expect any stronger
storm to have a chance. Temperatures today will only reach into the
70s across the north, but low to mid 80s across the south which
keeps heat indices under 90 today.

A stronger wave and surface low will lift through MN/WI and into the
U.P. tonight into Thursday which will pull the stalled cold front
back north as a warm front Wednesday night and a cold front through
on Thursday. CAMs keep the bulk of the precip across northern lower
with the warm front but most offer some isolated to scattered
convection farther SE along the warm front through the local area.
The cold front again offers a period of convection in the afternoon.
This looks to be a high CAPE, low shear environment as we get warm
sectored for a period. We will go with mainly chance pops with some
extra attention to the timing of the fronts.

The 590 dam ridge builds across most of the south heading out of the
workweek and into the weekend. Fairly zonal flow across the northern
tier of states which allows some heat to build back into SE MI with
highs back to around 90 this weekend. A stronger mid level trough
will track through Friday into Saturday offering yet another period
of thunderstorms in this active pattern. Shortwave ridge will
attempt to slide through Saturday into Sunday which could bring a
brief lull in precip chances to end the weekend.

MARINE...

A slow-moving cold front will continue to settle south through the
Great Lakes this morning as high pressure builds over Lake Superior,
affording a period of light N to NE flow. The low level frontal zone
will trigger additional shower and thunderstorm chances throughout
the day, especially this afternoon as the atmosphere becomes more
unstable. Isolated storms will be capable of wind gusts over 34
knots and large hail. Another wave of low pressure reinforces
unsettled conditions for Thursday and Friday, supporting additional
shower and thunderstorm chances as the frontal zone will still be
overhead. This wave will also draw southwest flow back into the
region, with wind gusts approaching 20 knots and waves above 3 feet.
Low pressure departs by the start of the weekend, with light
northwest flow filling in behind it.

&&

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

$$

AVIATION.....KGK
UPDATE.......BT
DISCUSSION...DRK
MARINE.......MV


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