639
FXUS63 KDTX 140849
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
449 AM EDT Mon Sep 14 2026

.KEY MESSAGES...

- Sunny and cooler with low humidity today.

- A chance of showers and thunderstorms returns Tuesday. The best
chance of storms is late afternoon and evening south of I-69.

- A chance of showers lingers Wednesday before becoming more
numerous Wednesday night and Thursday.

- Dry weather with temperatures around normal Friday into next
weekend.

&&

.AVIATION...

A dry and stable air mass is in place today with high pressure in
control, leading to light north to northeast winds (under 10 knots).
Mainly clear skies today, but a period of FEW-SCT VFR diurnal Cu is
likely, with best cloud coverage across the eastern Thumb region.
Mid to high based clouds will thicken up this evening and tonight as
a warm front lifts through the western Great Lakes into northern
Lower Michigan. Higher based showers are likely in the vicinity of
MBS and possibly FNT late tonight, with a very low chance of an
embedded thunderstorm.

D21/DTW Convection...No thunderstorms are forecast through tonight.

.DTW THRESHOLD PROBABILITIES...

* None

&&

.PREV DISCUSSION...
Issued at 357 AM EDT Mon Sep 14 2026

DISCUSSION...

The center of expansive surface high pressure drifts across central
Lower Mi to dominate conditions today. It has already delivered a
cool and dry air mass to the region as evidenced by temperature
observations dropping into the upper 40s outside of Detroit and away
from the shorelines. Also impressive is temperature guidance that
struggles to break 70 this afternoon despite full sun, although we
are getting closer to the equinox.

High clouds are on the increase this evening which signal a quick
transition to the next low pressure system. It is projected to move
out of the Rockies and along the Canadian border today and occlude
across NW Ontario tonight. This track sets up the low level jet and
plume of moisture transport from the central Plains into the
northern Great Lakes which then settles into central Lower Mi by
sunrise Tuesday. Behavior of regional and hi-res deterministic
models reflects a tendency for erosion of the precipitation pattern
by dry air lingering out ahead of the system. There is also some
breakup caused by the moisture axis outrunning the upper jet and mid
level short wave, both of which are positioned well to the north
across northern Ontario and the northern Great Lakes. Mostly chance
or scattered POP guidance in the NBM looks good in this regard until
flaring up later Tuesday afternoon. Daytime heating is projected to
boost convection by then, mainly across metro Detroit to the Ohio
border, as the cold front crosses the area into Tuesday evening. The
SPC Day 2 outlook grazes Lenawee and Monroe counties in a Marginal
Risk for severe intensity.

The surface cold front makes it south of the IN/OH border by
Wednesday morning where it stalls and wavers across central IN/OH
through Wednesday night and Thursday. This keeps a chance of showers
in the forecast for SE Mi, mainly south of I-69 as elevated portions
of the frontal zone are activated by southward expanding upper level
jet. The 00Z models maintain a consensus on a more coherent mid
level short wave and surface low pressure reflection along the
stationary front late Wednesday night and Thursday. ML/AI runs of
the GFS and ECMWF help narrow down areas closer to the Ohio border
for the highest POPs and QPF, and in general agreement with the WPC
Marginal outlook for excessive rainfall.

We get a break in showers/storms by Friday in the subsidence wake of
the passing short wave. Building surface high pressure drives the
frontal zone well down into the Ohio valley where it takes most of
Saturday to begin a northward return. Global/extended range models
bring the next low pressure system back into the upper Midwest
Saturday and through Lower Mi Sunday.

MARINE...

NW wind dropped off rapidly with the approach of broad surface high
pressure since midnight. The high moves across Lower Mi and Lake
Huron today on pace for a rapid transition of conditions ahead of the
next low pressure system. This system gains strength while tracking
across the Canadian Prairies tonight and Tuesday, and eventually
reaches the Hudson Bay region by Tuesday night/Wednesday. Southerly
flow out ahead of the system will increase across the north half of
Lake Huron with gusts now expected to reach gale force toward sunrise
Tuesday and continuing through mid afternoon. Concern for warm air
falling short of gales is balanced by model soundings that do
indicate a well mixed boundary layer within the inbound warmer air
mass, and this makes the wind profile capable of tapping into higher
gusts aloft. The Gale Watch is upgraded to a Warning in this forecast
update with the same effective time of 4 AM tonight through 4 PM
Tuesday. It was also decided to include zone LH361 as gusts reach
offshore of Presque Isle and extend northward across the Canadian
border. A band of showers and thunderstorms also accompanies this
gale event until pushed to the south and east by a cold front Tuesday
night.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Gale Warning from 4 AM to 4 PM EDT Tuesday for LHZ361>363.

     Small Craft Advisory from midnight tonight to 4 PM EDT Tuesday for
     LHZ421-422-441.

     Small Craft Advisory from 2 AM to 4 PM EDT Tuesday for LHZ442-443.

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

$$

AVIATION.....SF
DISCUSSION...BT
MARINE.......SS/BT


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