Expert Forecast Opinion

521
FXUS63 KDTX 140305
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1105 PM EDT Tue Oct 13 2026

.KEY MESSAGES...

- Some scattered showers tonight into Wednesday morning with a few
rumbles of thunder, mainly south of M-59.

- More seasonable and drier during the day Wednesday, followed by
additional rainfall Thursday afternoon into Thursday night.

- A strong cold front delivers gusty winds and much chillier
conditions Friday, with a few showers in spots.

- Turing drier through the weekend with slightly warmer readings by
Sunday.

&&

.AVIATION...

Post-frontal cool advection will allow stratus to continue expanding
southeastward from Mid MI across the Saginaw Valley and Thumb
through Wednesday morning. Highest confidence in MVFR ceilings is at
KMBS and KFNT. Meanwhile, a disturbance aloft brings scattered
showers and lower VFR cloud across the rest of SE MI during the
early morning hours, with isolated thunderstorms possible mainly
south of M-59. Based on latest trends with guidance and the cluster
of storms upstream, did include a thunder mention in the Metro
Detroit TAFs. Light NNW wind early Wednesday veers N and NE by
Wednesday evening as high pressure builds into the northern Great
Lakes. Inbound dry air favors scattering of lower ceilings by late
afternoon, with potential for Lake Huron stratus to then move inland
Wednesday night.

D21/DTW Convection...A cluster of elevated thunderstorms over
southern Lake Michigan may hold together as they track into the
airspace between 06z and 10z, so opted to include a TEMPO for TSRA.

.DTW THRESHOLD PROBABILITIES...

* Moderate for thunderstorms early Wednesday morning.

&&

.PREV DISCUSSION...
Issued at 346 PM EDT Tue Oct 13 2026

DISCUSSION...

Aggressive low and mid level drying outpaced last evening`s 00Z
models, yielding clear skies since the mid-morning hours. GOES water
vapor imagery continues to show widespread subsaturated air
encompassing the Great Lakes while the exiting low`s cold front
slowly clears toward the Michigan/Ohio border. Taking into
consideration the slow frontal progress, uninhibited insolation, and
850 mb temperatures hovering near 17C over Metro Detroit, recording
breaking heat remains in reach today, given the previous record of
just 83F. Further north, post-frontal flow has flipped west-
northwesterly which will spread southeastward through the evening
hours. The near-surface layer along the frontal slope cools faster
than the rest of lower column, leading to a more abrupt end to the
breezy afternoon conditions. Wind speeds drop off late tonight as
pressure gradient influence shifts from the low to an upstream ridge
of high pressure.

The 595 dam 500 mb Gulf Coast ridge remains anchored tonight as a
plume of 800-600 mb moisture releases anticyclonically from the
eastern Plains into the Ohio Valley amidst backing westerly flow.
Meanwhile, the frontal boundary stalls just south of the state line
as perturbed flow starts to work through aloft, helping trigger a
period of scattered showers. Models preserve a relatively narrow QPF
footprint with the highest totals (up to 0.25 inches) along/south of
I-94, mainly over the southern four counties. Light/trace amounts
are possible further north, up to M-59. In spite of RRFS forecast
soundings showing an inversion layer from 2.5-6.5 kft, lapse rates
above should suffice in generating pockets of 100-250 J/kg of
elevated CAPE. As a result, a few rumbles of thunder cannot be ruled
out.

There could still be a few lingering showers exiting the area by
sunrise Wednesday, followed by mainly dry conditions settling for
the rest of the daylight hours. Broad surface high pressure
influence extending from Manitoba to Southeast Michigan ushers in a
cooler continental airmass. The resulting shift to northerly flow
helps to nudge the existing vicinity boundary further into the Ohio
Valley throughout the day. Weaker winds expected as split-flow
ensues below 700 mb, limiting gusts to less than 15 mph. The next
round of showers arrives Thursday as a southern stream closed low
lifts from the desert southwest into the Plains, phasing with a
digging positively tilted longer wavelength trough. Supporting
dynamics and a spike in upper level divergence will engage a robust
theta-e plume lifting up the Mid-Mississippi Valley and eventually
bringing rain to southern Lower Michigan. High uncertainty exists in
the onset time for rain, reflected by the gradual northeastward
expansion of Chance PoPs after 12Z, per NBM. The bulk of the
rainfall should occur Thursday evening, or early Thursday night as
the northeast flank passes over Southeast Michigan, well downstream
of the deepening surface low, still located near the southern shores
of Lake Michigan. The low then traverses southern Lower Michigan
late Thursday night before crossing into Lake Huron Friday morning.

Turning colder and much windier on Friday as the system`s cold front
clears through. Aggressive constriction of the pressure gradient is
possible in its wake, although there is a noticeable difference in
the magnitudes of the deterministic solutions. The column will cool
at similar rates, but should see the mixed-layer expand sufficiently
for 35-45 knot lower tropospheric flow to mix down. Gusts in the 35-
45 mph range cannot be ruled out Friday afternoon and evening.
Additionally, a deformation axis trails, which could help spur some
light scattered rain showers. Chilly overnight with temperatures
dropping near or slightly below freezing, particularly north of I-
69. Turning drier through the weekend with slightly warmer readings
by Sunday, returning to climatological averages.

MARINE...

Conditions remain very stable under southwest flow as air
temperatures remain warm for this time of year which has tempered
gust potential. There will be a window this evening where winds back
to the west as low pressure departs the region. This window of
backed flow is where elevated mixing depths just will be high enough
to where gusts around 20 to 25 knots are possible. Small Craft
Advisories remain in effect from the Saginaw Bay to Port Huron for
this potential. Any elevated winds will then quickly diminish in the
later evening hours as the pressure gradient rapidly weakens.

A cold front will then push through the Great Lakes tomorrow,
stalling across southern Michigan by the afternoon. The favorable
northwest fetch will produce wind gusts 20 to 30 knots across
northern Lake Huron. High pressure to then build in through Thursday
which will bring a period of light winds for the day. Confidence is
increasing for a strong cold front to pass Friday into Saturday.
Instability will increase over the lakes in the wake of the front as
cold air flows over the warmer waters. Coupled with longer duration
northwest flow, a high-end gale event is looking increasingly likely
to end the week.

CLIMATE...

Record high max temperatures for October 13th:

Detroit: 83 Degrees (Set in 1975)
Flint: 83 Degrees (Set in 1975)
Saginaw: 86 Degrees (Set in 1930)

&&

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

$$

AVIATION.....TF
DISCUSSION...KGK
MARINE.......AM
CLIMATE......KGK


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