255
FXUS63 KDTX 060940
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
540 AM EDT Mon Oct 6 2025

.KEY MESSAGES...

- Warm temperatures continue today.

- Showers and scattered thunderstorm tonight, with showers lingering
into Tuesday.

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

&&

.AVIATION...

VFR to start that day as mid-Atlantic high pressure maintains
control. Upstream, a cold front stretches from the Upper Peninsula
to Kansas, which will pivot toward the airspace early Tuesday
morning. Moisture advection ahead of the front will be assisted by
return flow as winds hold out of the southwest today, allowing VFR
ceilings to develop between 4.0 and 6.0 kft agl with daytime
heating. Synoptic moisture arrives late tonight (after 04z roughly),
generating instability and a swath of rain/low thunder chances and
potential for lowering cigs/vsby. There is a consistent model signal
for IFR restrictions for a brief period Tuesday morning as the front
tracks through, followed by a rapid clearing response post-front. An
abrupt wind shift from SW to N/NW is expected with the fropa as
well.

For DTW/D21 Convection...Thunderstorm activity today/tonight stays
north of DTW. There is then a low chance (30%) for thunderstorms to
impact the airspace Tuesday morning as early as 07z, but more likely
between 10z and 14z.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling 5000 ft or less through this afternoon, increasing
  to high by early Tuesday morning.

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

&&

.PREV DISCUSSION...
Issued at 312 AM EDT Mon Oct 6 2025

DISCUSSION...

Southwest flow preceding a slow moving cold front has limited
nocturnal cooling and will result in a seasonally mild temps at
daybreak in the 60s. This will give way to another day of afternoon
highs into the 80s as the southwest flow and daytime heating support
a deep and well mixed boundary layer. Slight prefrontal moisture
advection in the low to mid levels will result in a little more
diurnal cloud cover this afternoon. Can not rule out some shallow
late afternoon convection, likely limited on coverage and intensity by
continued mid level capping.

Deep layer troughing moving across northern Ontario tonight into
Tuesday will drive the cold front across the Great Lakes region. The
deep layer front will largely remain parallel to the deep layer
southwest flow across Lower Mi tonight into early Tuesday morning,
resulting in a very slow moving frontal system. A veering of the low
to mid level flow to the west- northwest will help force the front
southeast of the forecast area on Tuesday. A region of high deep
layer moisture is forecast to lift into the northern Ohio Valley
tonight. There is still respectable model agreement indicating the
northern edge of this moist plume will get transported into the
frontal system. The placement of an upper jet streak(s) and small
scale mid level short wave impulses will help sustain intervals of
low to mid level frontogenesis tonight into Tuesday. There are
several high res solution which indicate a more focused region of
ascent arriving late this evening into the early portion of the
overnight, targeting the northern half of the forecast area. There
are even indications of a surface reflection along the cold front.
Weak to possibly moderate elevated instability will support a
respectable convective response. While the instability axis will
shift southeast Tues morning, frontal forcing higher up the frontal
slope will persist across at least the southern portions of the
forecast area into Tues afternoon, warranting continued rain chances.
The cold front, which will move through Se Mi overnight into Tuesday
morning, will be characterized by a strong thermal gradient in the
boundary layer, leading to much cooler post frontal temperatures on
Tuesday.

Strong high pressure associated with a building mid level ridge over
the upper midwest/Manitoba/nrn Ontario will expand across the Great
Lakes region Tuesday night into Wednesday. North-northeast low level
winds preceding this high will sustain decent cold and dry air
advection into Wed afternoon, leading to seasonally cool
temperatures. In fact, conditions will be favorable for some
locations to experience frost Thurs night. As the high departs to
the east, return flow will support a warming trend into next
weekend, with forecast highs into the upper 60s/low 70s.

MARINE...

Low pressure tracking through northern Ontario this afternoon and
into James Bay tonight will maintain south-southwest flow into
tomorrow. Winds looks to be mostly in the 15 to 20 knot range, but a
few gusts up to 25 knots will be possible over Lake Huron as cold
front approaches. The continued progression of low pressure into
Quebec will then push a strong cold front across the region late
tomorrow into Tuesday morning. Wind direction will veer to the north
after the passage of the front. Post frontal cold air advection will
sustain breezy conditions across Lake Huron Tuesday as 850 MB temps
fall into the low to mid single numbers. A period of wind gusts in
the 25 to 30 knot range are expected before winds diminish on
Wednesday as expansive high pressure arrives.

HYDROLOGY...

Rainfall probabilities across Southeast Michigan are quite high
tonight through Tuesday morning as a deep layer frontal system
slowly works its way across the area. Weak to possibly moderate
instability will support a convective component to the rain. This
and possibly narrow regions of enhanced frontal forcing suggest a
wide range in total QPF amounts across Se Mi, with some areas
possibly receiving under a tenth of an inch. This is also noted in
QPF probabilities and various hi res model QPF output. 12 hour
conditional convective probabilities indicate a 10 to 20% chance for
2 inches or more, while basin average precip totals are most likely
to fall into the quarter to half inch range. In light of the recent
dry conditions, flooding is not expected. Localized urban flooding
may be of concern should a more persistent area of convection become
established over the metro Detroit region. Confidence on this
scenario is low at this time.

&&

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

$$

AVIATION.....MV
DISCUSSION...SC
MARINE.......SF
HYDROLOGY....SC


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