189
FXUS63 KDTX 291804
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
204 PM EDT Sun Jun 29 2025

.KEY MESSAGES...

- Warm and humid conditions return today with highs near 90 degrees.
Heat indices Monday afternoon will be near 90 degrees.

- Showers and thunderstorms are likely on Monday, mainly during the
afternoon and evening. There is a marginal risk of severe weather
for portions of Southeast Michigan.

- Classic summer weather pattern during the middle to end of the
week with daytime temperatures well into the 80s.

&&

.AVIATION...

High degree of afternoon stability within the atmospheric column
ensures a dry forecast for the rest of today and tonight as surface
high pressure migrates further east, into upstate New York. Diurnal
cumulus response continues to wane as mixing depths increase,
eventually leading to a period of SKC conditions by this evening and
into the early overnight hours. High cirrus spills in tonight as
upstream convection vents into Lower Michigan. Lower column moisture
will advect into the region Monday morning with increasing dewpoint
temperatures yielding unstable conditions behind a lifting warm
front. This will trigger scattered thunderstorm development as early
as 16Z. Did include a PROB30 for this activity, although location
specifics are still murky. Ceilings also fill in, but should remain
VFR on Monday while visibility reductions to IFR cannot be ruled out
due to high rainfall rates with any storms that pass over the
terminals. Light surface flow generally holds within a SSW pattern.

For DTW/D21 Convection...Potential exists for scattered
thunderstorms after 16Z Monday. Enough evidence to support a PROB30
and a TEMPO after 18Z as coverage increases.

THRESHOLD PROBABILITIES...

* Low for thunderstorms after 16Z Monday, then medium after 18Z.

* Medium for ceiling at or below 5000 ft Monday afternoon.

&&

.PREV DISCUSSION...
Issued at 400 AM EDT Sun Jun 29 2025

DISCUSSION...

The center of 1019mb surface high pressure will build across the
central Great Lakes aggregate this morning to portions of PA and
upstate NY by this afternoon. NWP progs are very aggressive in
advecting/lifting a relatively shallow 950-850mb warm front through
the area into the Lake Huron basin by the afternoon. Expecting a
combination of deeper mixing and an uptick in surface dewpoints to
bring very warm conditions, heat indices in the lower 90s, although
the relatively shallow thetae return will maintain higher static
stability and convective inhibition between 2.5 and 7.0 kft agl.

A midlevel trough will push through the Great Lakes region Monday
and Tuesday. Forecast data depicts a trough that will remain in a
positive tilt while harboring 2 disorganized shortwave maxima. The
main geopotential height fall response with the system is expected
to occur during the daytime Monday as ragged, weak lead wave energy
ejects northeastward in advance of the trough. Magnitude of surface
based instability at 2000-3000 J/kg Monday will bring a strong to
severe thunderstorm threat but the lack of kinematics will limit 0-
6km bulk shear to 25 to 35 knots during the late afternoon. Storm
mode of multicell may support damaging wind gusts between 2pm-10pm
Monday with precipitation loading and wet microbursts. The potential
does exist for some isolated short live linear structures as
convective transitions to outflow dominant.

Northwesterly flow system relative isentropic descent will bring
subsidence and a modest lowering of humidity for the middle to end
of the week. More comfortable, but nonetheless, classic summer
weather conditions are anticipated. Looking at daytime highs in the
80s Tuesday through Friday (0 to 5 degrees above normal) with
dewpoints predominately in the 60s. There doesn`t appear to be much
potential for organized precipitation during middle to end of
the week period.

MARINE...

Light winds and low waves over the Central Great lakes to start the
day as a ridge of high pressure exits east. As a result, light
southerly flow under 20 knots develops this afternoon ahead of the
next low pressure system, which enters the northern Great Lakes
Sunday night into Monday driving a stronger cold front through the
region. This cold front will provide additional storms Monday and a
stronger post-frontal wind field Tuesday, around 20 knots

&&

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

$$

AVIATION.....KGK
DISCUSSION...CB
MARINE.......SF


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