095
FXUS63 KDTX 220753
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
353 AM EDT Sat Aug 22 2026

.KEY MESSAGES...

- Scattered to numerous showers and thunderstorms this morning become
  more widespread this afternoon.

- There is a Marginal/Isolated risk of strong/severe thunderstorms
  this afternoon.

- Breezy and cooler conditions arrive Sunday with scattered showers
  through Sunday night.

- A stray shower in the morning, otherwise dry Monday with slightly
  below normal temperatures.

&&

.DISCUSSION...

An active period of showers and thunderstorms continues in a couple
of phases as Straits low pressure pulls a cold front through Lower
Mi today. Clusters of showers and thunderstorms that are ongoing
leading up to sunrise are within the low to mid level moisture axis
ahead of the cold front. This is where model soundings indicate a
deep layer of elevated instability, but with minimal CAPE density
shown in both the soundings and implied by plan view depictions of
850 mb LI around -2 C and sub 7 C/km 700-500 mb lapse rate. This
elevated convection merges with scattered hybrid surface based
activity of similar intensity during the morning within and between
a prefrontal surface trough and the inbound cold front.

The early day activity adds some doubt about verification of model
peak instability as the cold front sweeps through SE Mi this
afternoon. However, HREF and REFS members all handle the ongoing
activity reasonably well and still suggest a respectable recovery in
time for the front to support a storm flare-up while overhead and
before it exits into Ontario toward early evening. There is
otherwise no big change in the CAPE/shear environment as HREF mean
surface based CAPE holds below 1500 J/kg with bulk shear around 25
knots, good enough for multicell clusters capable of peak gusts
approaching severe intensity as the primary hazard in the strongest
storms. The Marginal Risk remains in place to highlight this
potential in SE Mi with a Slight Risk now just east of the border
until the front exits early this evening.

Scattered showers trail the front, mainly during the evening, as the
500 mb trough digs toward the eastern Great Lakes, but also as
moderate cold advection gains traction overnight. Increasing NW flow
occurs across Lower Mi around the west flank of surface low pressure
deepening on the Ontario/Quebec border as the 500 mb trough deepens
and closes off early Sunday. Model agreement maintains the trend on
solutions offering a larger mid level circulation closing off closer
to Lower Mi during the day. There is also a well-defined reinforcing
vorticity maximum holding consistency in model solutions as it digs
in from the NW and moves overhead during the afternoon. Guidance
probabilities for rain appear underdone in this environment as
scattered to numerous coverage is favored, especially Sunday
afternoon and evening with a boost from daytime instability.

The low level thermal trough is firmly in place over the western
Great Lakes by Monday morning with low temperatures in the upper 40s
still within reach outside of the larger metro areas. Deterministic
and ensemble model guidance continue to project single digit 850 mb
temperatures to start the day which rebound quickly as the mid/upper
level low shifts eastward. A stray shower also remains in play,
especially toward the Thumb region, during the morning until
confluent NW flow develops to help ensure dry weather for the
afternoon and Monday night. Slightly below normal highs in the upper
70s are reachable as the thermal trough shifts eastward.

Weak surface high pressure is supported by a mid/upper level short
wave ridge Monday night and Tuesday. Dry weather and a few degrees
of warming occur through mid week within the slowly progressive
large scale flow. High temperatures return to the lower 80s during
mid week while the next chance of rain is carried in by the current
Pac NW system. Extended range global models project it arrives in
the Great Lakes by Wednesday.

&&

.MARINE...

A cold front will progress across the Great Lakes while expanding
shower and thunderstorm chances today. Any stronger storm
development will be capable of producing wind gusts aoa 34 knots
and/or small hail. Winds veer to the northwest in the wake of the
passing front and will increase intensity and remain elevated
through Sunday as cooler air is ushered in. Wind gusts will likely
range around 25 to 30 knots through this weekend. The switch in wind
direction from the northwest will quickly build wave heights in and
around the Thumb and Small Craft Advisories are in effect beginning
tonight. High pressure builds back in Monday and Tuesday which will
bring lighter winds to the area.

&&

.PREV DISCUSSION...
Issued at 1208 AM EDT Sat Aug 22 2026

AVIATION...

Predominately VFR ceilings through the early morning hours as
increased moisture supports higher coverage of mid/high clouds while
winds hold out of the S to SE. There remains low potential for stray
rain showers through the early morning hours, but coverage remains
low enough to preclude mention through remainder of tonight. Better
chance resides across FNT/MBS during the mid to late morning hours.
Cold front mid-day will bring widespread coverage of showers with
scattered thunderstorms along with potential for MVFR ceilings with
the passage of the front. Winds become westerly by the afternoon and
increase up to around 10 knots then becoming northwesterly in the
evening.

D21/DTW Convection... Very limited chance for an isolated
thunderstorm remainder of tonight and low enough to leave mention
out of TAFs. Increasing coverage of convection is expected to occur
after noon with the highest probability between 18 and 23z.

DTW THRESHOLD PROBABILITIES...

* Very low for thunderstorms tonight. Moderate after 18z today.

* Low for ceilings at or below 5000 ft this morning. Moderate in the
  afternoon.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...None.

Lake Huron...Small Craft Advisory from 8 PM this evening to 10 AM EDT Monday for
     LHZ421-441.

     Small Craft Advisory from 8 PM this evening to 4 AM EDT Monday for
     LHZ422.

     Small Craft Advisory from midnight tonight to 10 AM EDT Monday for
     LHZ442-443.

Lake St Clair...None.

Michigan waters of Lake Erie...None.

&&

$$

DISCUSSION...BT
MARINE.......AM
AVIATION.....AA


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