647
FXUS63 KDTX 130959
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
559 AM EDT Mon Oct 13 2025

.KEY MESSAGES...

- Dry weather to start the week with temperatures 5 to 10 degrees
above normal.

- A dry cold front moves through the area Tuesday leading to cooler
temperatures Wednesday.

- There is also an increasing probability of rain Wednesday morning,
currently at about 30 percent.

- Dry weather and normal mid October temperatures resume during the
late week.

&&

.AVIATION...

Saturated near surface conditions support areas of fog and low
stratus across much of the region early this morning. Conditions
vary considerably from terminal to terminal with the most
widespread/persistent LIFR along and west of US-23. Fluctuations in
flight category can be expected through daybreak. Based on trends
thus far, preference was to keep prevailing MVFR and tempo IFR/LIFR
with slow improvement after 13 to 14Z. MVFR ceilings are likely to
persist through mid-morning before lifting to VFR this afternoon. A
weak gradient maintains light and variable wind through the day.
Lack of onshore flow tonight suggests lower potential for fog and
low cloud Tuesday morning, but cannot rule out some localized
pockets developing particularly near Lakes Erie and St. Clair.
Meanwhile, mid level cloud arrives across the Saginaw Valley tonight
as a dry cold front sinks in from the north.

For DTW/D21 Convection...No thunderstorms through the taf period.

DTW THRESHOLD PROBABILITIES...

*  Medium for ceilings aob 5000 ft agl through this morning.

*  Low for visibilities aob 1/2 sm or ceilings aob 200 ft through
   13z.

&&

.PREV DISCUSSION...
Issued at 350 AM EDT Mon Oct 13 2025

DISCUSSION...

Late night/early morning observations show mild air entrenched
across the central Great Lakes that is heavily augmented by moisture
from Lake Huron, Erie, and also Lake Ontario given the easterly wind
trajectories. This means another round of fog and stratus across
Lower Mi with varying coverage depending on surface wind resilience.
Cirrus inbound from the Midwest frontal zone does little to disrupt
the otherwise standard mid October daytime heating influence on fog
and stratus trends during the morning. The boundary layer moisture
then mixes into a cumulus field just as clouds from the Midwest cold
front approach from western Lower Mi this afternoon. Upstream
observations at press time support model initializations of a broken
band of rain showers within the leading theta-e ridge. Model
agreement also remains overwhelming on dissipation of the showers as
the front moves into Lower Mi well to the south and east of mid
level short wave and upper jet support in Canada. The 500 mb ridge
is actually shown to build over the central Great Lakes today until
getting nudged eastward which allows the front to finish moving
through SE Mi Tuesday morning. Until then, temperatures continue a
run of 5 to 10 degrees above normal today and Tuesday before low
level cold advection gains traction Tuesday night.

Wednesday is set to be the coolest day of the week as Canadian high
pressure builds into Lower Mi dropping high temperatures back into
the upper 50s to lower 60s. Clouds will also be a factor along with
increasing probability for rain as elevated sections of the Tuesday
front linger overhead. The surface front is well south toward the
Ohio valley while the 850-700 mb theta-e gradient sets up across
Lower Mi late Tuesday night and Wednesday morning. Consensus of
deterministic models is trending upward on rain probability during
this time as the upper jet and a low amplitude 500 mb wave activate
the mid level frontal zone until driving the pattern south of the
IN/OH border by afternoon.

The larger scale mid and upper level flow amplifies considerably
during late week resulting in a ridge centered on the Midwest by
Thursday. This supports dry weather and a broad area of surface high
pressure across the central Great Lakes. Extended range/global model
solutions are then in general agreement on slow eastward progression
of the ridge across Lower Mi through Friday. Solutions are mixed on
the eastward extent of precipitation by then as a large low pressure
and frontal system organize from central Canada down through the
Plains heading into next weekend.

MARINE...

Influence of ridging gradually wanes today as winds turn more
southeasterly. Low pressure lifting out over the Hudson Bay allows
the local gradient to slacken resulting in winds falling below 15kts
by this afternoon and persisting through most of tonight. Associated
cold front eventually pivots across the central Great Lakes ushering
in moderate northwesterly flow Tuesday with peak gusts reaching
between 20-30kts- strongest over the open water zones of Lake Huron.
Small craft advisories will likely be needed around the Thumb due to
the favorable wind direction bringing higher wave action into the
nearshore waters. A few light showers are also possible along this
front late Tuesday however the bulk of the region remains dry. High
pressure sinking out of the Canadian Prairie then builds across the
region midweek.

&&

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

$$

AVIATION.....TF
DISCUSSION...BT
MARINE.......KDK


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