153
FXUS63 KDTX 230355
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1155 PM EDT Sun Jun 22 2025

.KEY MESSAGES...

- Very hot and humid today through Tuesday.

- Extreme heat warnings in effect for the Detroit and Flint urban
areas, heat advisories in effect across the rest of Southeast
Michigan.

- Periods of showers and strong thunderstorms Tuesday afternoon
through Friday.

&&

.AVIATION...

Large amplitude H5 597 dam ridge is centered over portions of the
Ohio River Valley. Primary influence on the weather throughout the
taf period will be the very low absolute moisture in the mid-upper
levels. Forecast soundings support strong stability and convective
inhibition in the 3.5 to 14.0 kft agl layer. VFR conditions are
forecasted throughout the period. Sparse boundary layer cumulus at
3.5 kft agl will be possible Monday. Convective activity may
approach the area to the north of KMBS Monday evening, but strong
model signal that stout capping will limit southward progression.

For DTW/D21 Convection...No thunderstorms are forecast.

 THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 357 PM EDT Sun Jun 22 2025

DISCUSSION...

The Heat Warning/Advisory continue across SE Mi with Genesee county
added to the warning in this update. Heat index reached 105 at FNT
combined with cumulative urban vulnerability along the I-69 corridor
worthy of the upgrade for today through Tuesday.

The textbook high pressure heat wave pattern is locked in across the
eastern U.S. to finish the weekend. Observations and model analysis
fields indicate surface high pressure near 1025 mb centered over the
Carolinas which is under a 500 mb ridge building to near 600 dm
covering the eastern third of the country. This setup is easily
delivering on the promised heat and humidity as afternoon
observations show a broad footprint of 90s/70s T/Td from the Gulf
coast into the Great Lakes supporting reports of heat index in the
lower 100s at most locations across SE Mi.

Additional consideration for the Heat Advisory/Warning is the lack
of relief at night which was already demonstrated last night and
continues tonight. SW wind will be less breezy but have a similar
influence on elevating temperature in the mid to upper 70s with
corresponding heat index hovering around 80 through Monday morning.
Cumulative impact stacks up even more as Monday turns out nearly
identical, at least in terms of heat index. T/Td guidance continues
to show some variation toward afternoon highs more firmly in the
upper 90s while Td drops back into the upper 60s/lower 70s having
the same end result of heat index near 105 for several hours again
in the afternoon, which then only drops back into the mid 70s to
around 80 again Monday night.

Heat continues into Tuesday although forecast confidence wavers as
clouds/showers/storms enter as complicating factors on temperature
as soon as early Tuesday morning. Consensus of 22/12Z deterministic
models brings a northern stream short wave across central Canada
which is able to suppress the eastern U.S. ridge just enough for a
weak front to follow into central Lower Mi early in the day. This
front is the subject of SPC`s Day 2 Outlook that has a Marginal Risk
grazing the Saginaw Valley and Thumb outlining the south/east extent
of potential survival of surface based storms from Monday afternoon.
New development during Tuesday is more likely toward the Tri Cities
and Thumb leaving Detroit open to continue hazardous/dangerous heat.
The front stalls near the Ohio border Wednesday while exchanging
heat for an active storm pattern for the late week period.

MARINE...

Strong ridging aloft maintains dry and warm conditions for the local
waters today and Monday. Southwest winds hold firmly in place in
between mid-Atlantic high pressure and northern Plains low pressure.
The SW flow funnels along the long axis of Saginaw Bay to support
wind gusts above 25 knots on Monday, necessitating Small Craft
Advisories Monday afternoon-evening as a low level jet slides
overhead. This jet precedes an incoming trough axis/weakening
frontal zone that slowly settles into the Great Lakes late Monday
night and stalls overhead through at least mid-week. Increasing
shower and thunderstorm chances are expected Tuesday onward as a
result of this feature, and will have to be monitored for strong to
severe potential.

&&

.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...Small Craft Advisory from noon to 8 PM EDT Monday for LHZ421-422.

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

$$

AVIATION.....CB
DISCUSSION...BT
MARINE.......MV


You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.