730
FXUS63 KDTX 111103
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
703 AM EDT Fri Jul 11 2025

.KEY MESSAGES...

-Warmer summertime pattern underway today, continuing into the
weekend as humidity and heat indices trend higher.

- Increasing potential for showers and thunderstorms today then
higher likelihood by Saturday which could produce isolated severe
storms and localized heavy rainfall.

- Drying out early by Monday with temperatures at or above 90F
Tuesday, and maybe Wednesday.

&&

.AVIATION...

SW Lower Mi showers and a rumble of thunder were holding on within
the underlying MCV circulation and lingering nocturnal/elevated
instability. The latest radar trend shows a few flare-ups within a
general decreasing trend toward FNT and PTK early to mid morning.
Additional activity farther upstream toward southern Lake Mi and CHI
follow similar evolution by late morning into early afternoon.
Conditions are generally VFR otherwise as the front that is stalled
at the Ohio border moves northward during the day while becoming the
focus for additional storms as instability builds and as additional
activity moves in from the Midwest mid to late afternoon through
this evening. Greater coverage over a longer time period is favored
generally north of PTK through midnight. SE Mi then settles into the
warm sector ahead of a broad Midwest cold front supporting VFR
conditions in warm south flow late tonight into Saturday morning.

For DTW/D21 Convection... Low chance for decaying showers/rumble of
thunder this morning. Greater thunderstorm potential builds after
18Z through this evening.

THRESHOLD PROBABILITIES...

* Low for ceiling 5000 ft or less outside of thunderstorms.

* Low for an isolated thunderstorm this morning. Medium for
  thunderstorms this afternoon and this evening.

&&

.PREV DISCUSSION...
Issued at 359 AM EDT Fri Jul 11 2025

DISCUSSION...

Warmer summertime pattern underway today, continuing into the
weekend as humidity and heat indices trend higher. This also
contributes to an increase in thunderstorm chances as instability
metrics respond to rising dewpoints. Currently monitoring a decaying
MCS over Southwest Michigan which could produce some late morning or
midday convection, locally. Synoptic ascent owing to a mid-level
speed max and elevated instability have helped sustain such upstream
convective remnants. However, as the embedded wave weakens upon
arrival around 15Z, timing will become unfavorable relative to the
diurnal heating cycle. Should some component of an outflow boundary
remain, this could reignite a few more productive updrafts as
activity works further east across Southeast Michigan, more so after
18Z. At press time, SPC mesoanalysis shows a total lack of MLCAPE
and EBS. A secondary round of storms will be possible later this
afternoon as the atmosphere destabilizes, but environmental dynamics
turn less supportive. Overall severe threat and confidence in
today`s setup is low while high temperatures maximize a couple
degrees warmer than Thursday (mid to upper 80s).

CAMs highlight some decay in convection early tonight as nocturnal
stabilization attempts to take root, but the possibility for renewed
upstream MCS development/propagation warrants at least Slight to
Chance PoPs (20-40 percent). The axis of impressive ThetaE
advection, coincident with a highly confluent southwesterly LLJ,
extends into the northern Great Lakes. This should overlap more
effectively with the Tri-Cities and Thumb regions which are favored
for prolonged overnight storms. Still highly conditional on upstream
convective trends.

A stalled frontal boundary draped just south of the MI/OH/IN border
gets forced northward across Lower Michigan on Saturday as a warm
front. Marked increase in 850 mb temperatures is anticipated (upper
teens to near 20C) which translates to highs broadly near 90F.
Convective disruption could prevent more pronounced warming,
considering the higher likelihood for storm development amidst a
more unstable airmass (SBCAPE to 2500 J/kg). Shear profiles are a
bit weaker, but primary threat will be isolated wind gusts to 60 mph
and torrential rainfall/flooding, once PWATs approach 2 inches. A
shortwave trough axis aloft provides background ascent and then
slides east into Ontario around 06Z (Sunday) ending showers/storms
for most.

Slightly cooler/drier airmass expected Sunday as a cold front slows
upon exiting. Some hints of renewed convective development for the
southeastern half of the forecast area, along a fading instability
gradient as the main upper level trough axis crosses overhead.
Geopotential heights start to rebound early next week as a more
cohesive anticyclone organizes over The Southeast. Zonal jet
situates just to the north with a deepening longwave feature
extending over southern Lower Michigan as soon as Wednesday. This
offers the next opportunity for convective activity as an embedded
trough works through the mean flow. Decent agreement in medium-range
solutions for thermal troughing overspreading the Midwest by the end
of the workweek.

MARINE...

Showers and thunderstorms remain possible later this morning into
the early afternoon from a decaying storm system that is expected to
weaken as it travels into the eastern Great Lakes. It is possible
some lingering thunderstorms can affect the region leading into the
afternoon hours. A secondary round of showers and thunderstorms will
then again move in from the western Great Lakes with some
development possible overhead, which brings the potential to see
strong to severe storms in the later afternoon and evening hours.
Small hail and wind gusts in excess of 40 knots will be the main
threats with any stronger storms. Additional shower and thunderstorm
chances will enter this weekend ahead of and along a cold front
which brings some renewed chances for some stronger storm
development.

Outside of thunderstorms, a weak pressure gradient will maintain
light wind speeds today, with some elevated gust potential entering
by the weekend as the pressure gradient strengthens with the
aforementioned cold front.

&&

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

$$

AVIATION.....BT
DISCUSSION...KGK
MARINE.......AM


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