839
FXUS63 KDTX 041650
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1250 PM EDT Sat Oct 4 2025

.KEY MESSAGES...

- Dry with near record warmth this weekend.

- The next chance of rain arrives late Monday into Tuesday.

- More seasonable temperatures the latter half of the week.

&&

.AVIATION...

Anti-cyclonic flow through nearly the entire column continues to
support broad scale subsidence and the lack of organized cloud
production. The near surface high center is anchored to the
southeast of the region, which will open the door for some modest
moisture advection into central Lower Michigan this afternoon. Thus
far, diurnal cumulus has failed to initiate - however, expectations
are for a cloud field to sprout with the near record warmth later
this afternoon. An isolated shower is possible with any congestus
patch that manages to gel - especially in vicinity of FNT or MBS.
Otherwise, light southerly flow will persist through Sunday morning -
then freshen toward midday as aggressive mixing occurs - and some
diurnal cumulus develop.

For DTW/D21 Convection... Thunderstorms will not occur through the
forecast period.

DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 357 AM EDT Sat Oct 4 2025

DISCUSSION...

Clear skies are noted this morning stretching from Texas to the
southern Great Lakes. A glancing shortwave perturbation has led to
isolated convection over northern MI, but this will remain confined
to the northern part of the state. Another dry and sunny start to
the day thus expected for SE Michigan, although temperatures this
morning are running about 10 degrees warmer than yesterday. Primary
discussion point today is near daily record high temperatures, which
will climb into the upper 80s this afternoon-evening. Anomalous
ridging and warm column temperatures (T in the 90th-99th percentile
in the sub-500mb layer) are driving this warm airmass on the larger
scale, while well-mixed profiles and lean moisture influence afford
little opportunity for underachievement.

Remnant mid-level stability provides enough of a capping inversion
to prevent deep convection today. That said, nearly all models do
generate a shallow (~5.0 kft) layer of instability at the top of the
boundary layer that is leading to weak simulated reflectivity
returns in the hi-res guidance. A stray, low impact shower cannot be
ruled out this afternoon.

Meanwhile, a deep Pacific wave traverses from the Four Corners
region toward the Plains Sunday. The wave takes on a negative tilt
and at this point induces a surface low that is driven poleward by
the parent wave. The Great Lakes reside between this low and the
departing high pressure, which holds steadfast over the mid-
Atlantic. The constricted pressure gradient leads to gusty southwest
flow, especially toward the Saginaw Valley/Thumb where afternoon
gusts approach 25-30 mph Sunday and Monday. The lead wave lifts well
north of the Great Lakes, with its cold front gradually dragging
eastward into the Great Lakes region. An active precipitation
response is expected within the frontal zone, especially considering
the deep layer of return flow that will be established at the this
time. Rain begins Monday afternoon across the north and gradually
expands south as the front slowly approaches the cwa.

The front will eventually be accelerated into SE Michigan Tuesday
morning as a potent shortwave breaks away from the polar low. This
initiates a more rapid height fall response, which will be coupled
with right entrance region jet dynamics to support strong synoptic
forcing with the fropa. Widespread rain is expected as a result, with
ensemble 24-hour QPF statistics still calculating an interquartile
range of 0.25-0.50" with upper 25th percentile values upwards of 1".
Timing of the front seems to favor a morning to mid-day passage,
ultimately limiting the amount of instability that can build into the
warm sector. So for now, the setup looks to favor mostly showers
with embedded thunder. Passage of the front signifies a significant
cool down with H8 temperatures dropping toward 0 C and daytime highs
settling into the low 60s. Overnight lows will also have a shot at
dropping below 40 degrees Wednesday and Thursday.

MARINE...

A series of low pressure systems will travel from the northern
Plains into the James Bay this weekend. While this will not result
in any significant changes across the Great Lakes, this will
strengthen the pressure gradient slightly, reinforcing southerly
flow across Great Lakes with gust potential ranging between 15 to 20
knots, favored across Lake Huron.

Much bigger changes arrive Monday as a strong cold front sweeps
across the Great Lakes. Prior the passage of the front, south flow
wind speeds will increase tomorrow night, bringing gust potential up
to 25 knots over Lake Huron. Intrusion of cooler air Tuesday will
bring continuation of breezy conditions, but the exact magnitude of
gust potential remains uncertain. Gusts up to 30 knots look possible
at this time.

CLIMATE...

The record highs for Today (Saturday, October 4th).

Detroit: 89 Degrees (Set in 1951)
Flint:   88 Degrees (Set in 1951)
Saginaw: 87 Degrees (Set in 1967)

The record highs for Sunday, October 5th.

Detroit: 88 Degrees (Set in 1951)
Flint:   88 Degrees (Set in 1922)
Saginaw: 86 Degrees (Set in 2007)

&&

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

$$

AVIATION.....Mann
DISCUSSION...MV
MARINE.......AM
CLIMATE......MV


You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.