929
FXUS63 KDTX 240359
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1159 PM EDT Mon Jun 23 2025

.KEY MESSAGES...

- Extreme heat warnings remain in effect for metro Detroit and
Flint, with heat advisories in effect elsewhere through tomorrow.

- Scattered to numerous showers with embedded thunderstorms will be
possible tomorrow afternoon and evening. Isolated to scattered
severe storms are also possible.

- Wet microbursts with wind gusts to 60 mph will be the most likely
hazard with any severe thunderstorm. Heavy downpours leading to
highly localized flooding will also be possible.

- Additional chances for thunderstorms will persist Wednesday
through Friday. Heavy rain will remain a risk through the end of the
week.

&&

.AVIATION...

The large amplitude ridge centered over portions of the Ohio River
Vally will remain the dominant influence throughout the next 12
hours. A dry airmass in the lowest 7.0 kft agl will result in a
stable environment and convective inhibition. No precipitation is
anticipated overnight. Model signal does suggest it will take
diurnal recovery to generate any activity Tuesday afternoon,
although confidence is very low on location and coverage.

For DTW/D21 Convection...The potential exists for thunderstorms
Tuesday between 20z-23z. Locally heavy rainfall will be possible.

 THRESHOLD PROBABILITIES...

* Low for thunderstorms Tuesday 20z-23z.

&&

.PREV DISCUSSION...
Issued at 356 PM EDT Mon Jun 23 2025

DISCUSSION...

Coming off of fresh record high minimums from the overnight hours,
temperatures now reside in the mid 90s across SE MI under full late
June solar insolation, where heat advisories and excessive heat
warnings remain in effect. This prolonged heat wave has been the
function of a anomalously strong 598-600 dam dome of high pressure
that continues to reside across the continental east, maintaining
southwest flow across the state where 850mb temperatures of 22C
remain in place. The 12Z DTX RAOB recorded 500mb heights of 594.3
dam, which is an all time high record per DTX RAOB climatology. Water
vapor imagery displays copious amounts of dry air over the state
which will maintain cloudless skies. All precipitation chances are
expected to remain north of the cwa, extended from ongoing convection
across Wisconsin that will travel into northern lower Michigan, tied
to a cold front. Another round of very warm overnight low
temperatures are expected as temperatures only fall into the mid-70s,
which will again challenge record high minimums.

Tomorrow will again bring hot conditions with another round of 90
degree temperatures expected through the northern Metro region, but
the breakdown of this record breaking ridge will commence as a series
of shortwaves ripple through the mean flow, turning mid-level flow
more zonal across the state. The aforementioned cold front will begin
to enter into SE MI but there are uncertainties with where exactly
the front will stall out, given some possible dynamics with early
morning convective outflows. This frontal zone will likely be the
initial spark for convection initiated from the low-level
convergence, at which point parcels can become extremely buoyant. Dry
adiabatic lapse rates through 2km under the unstable air mass with
MUCAPE values of 1500-2000J/kg will allow for rapid vertical
acceleration that will capitalize on the boost of moisture advection
from the breakdown of the ridge where PW values of 1.80 to 1.90
resides. The limiting factor for this setup will be poor to modest
at best shear with EBWD values capping out around 15-20 knots, max 25
knots. This will result in a pulse to multicellular convective
setup. Storm motions are very slow, less than 15 knots, so outflows
will be dominant, which can then initiate additional thunderstorms,
in addition to any lake breezes that move inland by the late
afternoon and evening hours.

Strong lapse rates in addition to long and skinny CAPE profiles with
entrainment of drier air above 500mb will bring potential to see
isolated to scattered strong to severe storms capable of producing
damaging wind gusts around 60 mph with wet microbursts potential.
This idea is reinforced noting DCAPE values around 1,200 and TEI
around 30 in forecasted soundings. Timing for convection, including
strong to severe storms will be from 19Z to about 01Z Wed. This will
all be conditional on positioning of the front, but at this time the
front looks to stall out somewhere between I-69 to I-94. Given the
slow storm motion and high PW environment, some highly localized
flooding will be possible, especially if storms set up across the
urban Metro region. Please see the hydrology section for additional
details.

This moisture axis will set up and reside right over SE MI through
Friday while the zonal flow puts us in the track for additional
shortwave to ripple overhead, bringing additional chances for
showers and thunderstorms Wednesday morning into late this week. The
big picture thermal profile and advection scheme will not
drastically change so warm and muggy conditions are still expected,
however, multiple chances for precipitation along with the
associated cloud cover will temper high temperature potential,
holding highs in the 80s.

MARINE...

Strong high pressure supports dry conditions for the rest of the
afternoon and early evening. Southwest flow funnels through Saginaw
Bay to push gusts above 25 knots for the rest of the daylight hours,
with Small Craft Advisories in effect as a result. A gradual pattern
shift occurs tonight-Tuesday as a frontal zone settles into the
Great Lakes. Implications of this can already be seen upstream as a
broken line of showers and storms works into the western Great
Lakes, which will move into northern Lake Huron late this evening.
Reinvigoration of this convection is expected during peak heating on
Tuesday for a broader portion of the forecast area, including the
nearshore zones. Isolated storms tonight-Tuesday may be strong to
severe with 34+ knot gusts and large hail possible. Thunderstorm
chances continue Wednesday through Friday while winds subside and
vary in direction through the period.

HYDROLOGY...

A cold front will bring scattered showers and embedded thunderstorms
tomorrow afternoon and evening. There is some uncertainty regarding
where the front will settle and thus where the most likely location
for better coverage of showers and storms will be, but the most
likely locations will be along or between the I-94 to I-69 corridor.
Given slow storm motions and high PW values, any thunderstorm
observed will be capable of heavy downpours leading to highly
localized rainfall accumulation totals. Any repeated thunderstorm
activity will have the potential to accumulate 1-2+ inches of
rainfall, which could lead to to urban and low lying flooding.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Heat Advisory until 8 PM EDT Tuesday for MIZ047>049-053>055-060-062-
     063-068-075-082-083.

Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

AVIATION.....CB
DISCUSSION...AM
MARINE.......MV
HYDROLOGY....AM


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