411
FXUS63 KDTX 291920
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
320 PM EDT Tue Sep 29 2026

.KEY MESSAGES...

- There is a chance of light rain tomorrow.

- Periods of rain is forecast Thursday into Friday. Locally heavy
rain is possible.

- Cooler and drier air is forecast Saturday.

&&

.DISCUSSION...

Mid level short wave ridging overhead will depart eastward across
the Lower Great Lakes tonight. Residual mid level subsidence will
support mostly clear skies through the evening. With the eastward
departure of sfc high pressure, an increase in the SSW gradient
tonight will limit radiational cooling, warranting milder nighttime
temps compared to the last few nights; forecast lows in mid 50s to
low 60s.

An axis of deep layer moisture now extending across the central
plains into northern Ontario will experience renewed tropical
moisture transport due to the remnants of Hurricane Polo and a
continued influx off the western gulf. A progressive northern stream
trough axis and mid level height falls across northern Ontario into
the northern Great Lakes tonight will drive this moist axis along
with a mid level tropospheric front across southern Michigan on
Wednesday. Mid level short wave impulses within the mid level theta
e advection will support moderate to high chances for rain through
the day Wed. Lingering low level dry air will keep the rain light
and relatively high based. Strengthening upper jet dynamics and an
increase in the low level inflow will tighten the frontal feature
overhead Wed night into Thursday and will likely drive some
semblance of a surface warm front toward Se Mi. This will support
continued rain chances and may allow temps near the Ohio border to
push 80 degrees Thursday.

Although an upper wave over the southern plains is forecast to
rapidly weaken as it lifts northeast Thursday into Fri, model PV
surfaces indicate phasing between northern and southern stream jet
streaks to the north and northeast of the Great Lakes. This will
result in intensification of mid level deformation across srn Lower
Mi Thurs afternoon into early Fri. Model solutions indicate a
corridor of very high moisture feeding into the elevated frontal
system. Precipitable water values across Se Mi are forecast to range
from 1.6 to 2.0 inches Thurs/Fri, within the 99th percentile for
early October PWATs if not pushing record territory. While weak
elevated instability may support some convective elements within the
rain, the kinematics will be supportive of a band of moderate to
possibly heavy rainfall. At this stage in the forecast there is
still uncertainty as to the precise location of the more persistent
forcing within the DTX forecast area. Probabilistic guidance
indicates moderate to high chances for total rainfall between 0.5
and 1.5 inches Thurs into Fri, with low probabilities for rainfall
totals of 2 or more inches. A northern stream trough is forecast to
drive the deep layer moist axis south of the area during the day
Friday, with much cooler and drier air advection following the
passage of the associated surface front. Broad high pressure will
expand across the area Saturday, leading to a cool and dry start to
the weekend.

&&

.MARINE...

South to southwest winds will slowly increase ahead of the next
cold front, which arrives and stalls over southern Lower Michigan on
Thursday. With warm advection leading to more stable profiles
and showers moving through during this timeframe, wind gusts are
expected to top out only around 25 knots. With the front hung up
into Thursday night, the post frontal cold advection now looks
slower; thus, the potential for northwest wind gusts reaching or
exceeding 25 knots looks to be late in the day on Friday as 850
MB temps lower into the mid single digits by Friday.

Another large area of high pressure building in on Friday night and
Saturday will promote light winds for the first half of the weekend.
A stronger low tracking through the northern Great Lakes for the
second half of the weekend brings another opportunity for winds to
reach or exceed 25 knots over Lake Huron.

&&

.HYDROLOGY...

The transport of tropical moisture into southern Michigan and an
approaching cold front will lead to widespread rain Wednesday into
Friday. The heaviest rain is forecast to occur between Thursday
afternoon and Friday morning. There is high probability for total
rainfall between 0.5 and 1.5 inches. A band of more persistent
rainfall is likely to become established across the area. The
precise location of this carries some degree of uncertainty at this
time. Within the model probability space, there is a chance for
rainfall to exceed 2 inches in areas which experience the more
persistent rainfall, suggesting at least a chance of minor flooding.

&&

.PREV DISCUSSION...
Issued at 104 PM EDT Tue Sep 29 2026

AVIATION...

A very dry and stable environment will hold firm through tonight,
sustained by lingering high pressure slowly exiting to the east.
This will maintain limited cloud production into the evening hours,
while winds remain modest from the south. Cirrus will thicken with
time tonight downstream of a low pressure system lifting through the
upper midwest. This cloud cover combined with persistent light
southerly gradient will preclude greater fog concerns for the early
morning hours. A more pronounced increase in mid level moisture will
offer some potential for showers to develop across mainly near MBS
starting later Wednesday morning. VFR conditions will persist all
locations as ceiling gradually lower throughout Wednesday.

D21/DTW Convection...No thunderstorms forecast through the TAF
period.

DTW THRESHOLD PROBABILITIES...

* None


&&

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

$$

DISCUSSION...SC
MARINE.......SF
HYDROLOGY....SC
AVIATION.....MR


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