403
FXUS63 KDTX 070132
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
932 PM EDT Mon Oct 6 2025

.KEY MESSAGES...

- Showers and scattered thunderstorms tonight and Monday morning,
  lingering into the afternoon toward metro Detroit.

- Much cooler conditions Tuesday through the end of the week.

&&

.UPDATE...

Clusters of showers and isolated thunderstorms continue to advance
into SE Mi this evening, slightly behind schedule but still set to
expand in coverage and intensity during the night. Ongoing activity
along and ahead of the front is weakly surface based in MLCAPE
around 500 J/kg according to hourly mesoanalysis. These will be
monitored for wind gust potential while moving along and near the I-
69 corridor this evening given some negative buoyancy shown in the
00Z DTX sounding. The setup gradually transitions to more of an
elevated character along and post front in a similar MUCAPE
environment. The boost in coverage and intensity comes as the
entrance region of the upper jet and 500 mb trough move closer from
the upper Midwest while energizing a low level jet response within
frontal zone/low level moisture axis. A band of showers solidifies
in this forcing with pockets of thunderstorms capable of localized
heavier rainfall rates across SE Mi, mainly toward the Tri Cities
and northern Thumb in most recent hi-res model projections. The
going forecast is then on track with a few tweaks to timing on the
front end this evening. Widespread showers and a few thunderstorms
continue through the morning until ending NW to SE and finally
exiting the Detroit metro area toward mid afternoon.

&&

.PREV DISCUSSION...
Issued at 708 PM EDT Mon Oct 6 2025

AVIATION...

A cold front moving NW to SE across Lower Mi is the primary forecast
focus for tonight and Tuesday. It brings increasing coverage of
showers and scattered thunderstorms to the SE Mi terminal corridor
this evening, while a few additional showers graze the DTW area,
peaking in coverage/intensity all areas after midnight into Tuesday
morning as the front moves overhead. The front also brings solid
coverage of MVFR ceiling with a greater IFR component also toward
sunrise while at the same time improving quickly from MBS southward
after sunrise. MVFR ceiling and post frontal showers linger longer
toward DTW, however a return to VFR is projected at all locations by
21Z Tuesday afternoon.

For DTW/D21 Convection... There is a low chance (30%) for
thunderstorms to impact the DTW airspace late tonight and Tuesday
morning.

DTW THRESHOLD PROBABILITIES...

* High for ceiling 5000 ft or less late tonight and Tuesday
  morning.

* Low for thunderstorms late tonight and Tuesday morning between 10z
  and 14z.

PREV DISCUSSION...
Issued at 301 PM EDT Mon Oct 6 2025

DISCUSSION...

Last day of the anomalously warmer temperatures is underway under
brisk southwest flow which have propelled temperatures back into the
80s this afternoon. A stark change in temperatures will arrive by
tomorrow after the passage of a cold front, which also brings shower
and thunderstorm chances.

A strong shortwave impulse will round into western Ontario through
the day today and will amplify the greater trough feature through
the northern Plains, aiding in the continued progression of a strong
cold front that now extends through northern lower Michigan. Slow
progression of the front will continue through the morning hours
tomorrow as deep-layer steering flow remains largely parallel to the
boundary. As the front arrives within the vicinity of and over SE
MI, numerous showers with embedded thunderstorms will move in, aided
from the efficient deep transport of high theta-e moisture coupled
with elevated instability.

Hi-res models continue to pick up on the potential for prefrontal
development late tonight through Midnight favored across the Tri-
Cities and Thumb. Unidirectional wind direction could promote some
isl to sct pulse or linear segmented convection. Some pockets of
localized gusty winds will be possible with this activity, but the
overall elevated nature precludes any stronger wording of damaging
gust potential. Frontal progression will then pick up through the mid
to late morning hours as flow aloft veers, enhancing the
frontogenetic response, especially across the Tri-Cities and Thumb.
The cold front and subsequent rain chances clear the cwa entirely in
the afternoon hours.

An anomalously strong surface high pressure system is then set to
build into the area through the midweek period, with central SLP
values expected to reach of exceed the 99.5th percentile of the
climatological distribution for this time of year. The extreme
strength is amplified by a synergistic dynamic setup. Specifically,
the Great Lakes will be situated beneath the right exit region of the
nnw-sse jet over Ontario which will maximize upper-level confluent
flow. Coupled with cold air advection in the low levels through 850mb
which increases density of the column, SLP increases and peaks by
Thursday morning. The passage of the cold front and thermal trough
brings stark temperature changes Tues-Thurs afternoon with highs in
the low to mid 60s and lows 30s (Wed-Fri morning). The coolest night
will likely be Thursday morning as lows drop into the low to mid 30s,
which will bring frost and freeze concerns. Otherwise, this
aforementioned setup brings dry weather and clear skies through the
midweek period.

MARINE...

A cold front will continue to slowly track south through the Central
Great Lakes this evening and tonight, with blossoming showers and
embedded thunderstorms expected. Stronger thunderstorms will be
capable of producing wind gusts of 35+ knots.

Post frontal cold air advection through tomorrow as 850 MB temps
fall into the low single numbers to near zero. A period of wind
gusts up to 30 knots is expected across northern Lake Huron Tuesday
evening with the increased boundary layer before winds slowly
diminish and veer north-northeast on Wednesday as expansive high
pressure arrives. Despite winds diminishing, the northerly flow will
lead to larger waves over the southern Lake Huron basin Tuesday
evening into Wednesday, with small craft advisories needed during
this time for the nearshore waters as the cold airmass leads to
unstable low level profiles conducive to good wave growth with the
long north-northeast fetch.

HYDROLOGY...

A cold front will bring numerous showers with embedded thunderstorms
to SE MI late tonight through tomorrow morning. Basin averaged
rainfall totals are expected to range between a quarter-inch to a
half-inch of rainfall, with some localized higher amounts likely
with any repeated shower or thunderstorm activity. The most likely
location for repeated activity will reside along or north of I-69,
through the Tri-Cities and Thumb, where totals closer to an inch or
more will be possible. Given the antecedent dry conditions,
localized flooding is not expected.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...None.

Lake Huron...Small Craft Advisory from 10 PM Tuesday to 10 PM EDT Wednesday for
     LHZ421-441>443.

     Small Craft Advisory from 10 PM Tuesday to 4 PM EDT Wednesday for
     LHZ422.

Lake St Clair...None.

Michigan waters of Lake Erie...None.

&&

$$

UPDATE.......BT
AVIATION.....BT
DISCUSSION...AM
MARINE.......SF
HYDROLOGY....AM


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