Expert Forecast Opinion

867
FXUS63 KDTX 131934
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
334 PM EDT Mon Oct 13 2025

.KEY MESSAGES...

- Pleasant fall evening with dry weather and temperatures in the 60s.

- A dry cold front moves through the area Tuesday leading to cooler
temperatures Wednesday.

- There is an increasing probability of rain Wednesday morning,
currently at about 30 percent.

- Dry weather and normal mid October temperatures resume during the
late week.

&&

.DISCUSSION...

Healthy diurnal cumulus field observed via visible satellite this
afternoon. Localized clear pockets reflect where widespread fog/low
stratus lingered this morning and disrupted the mixing process.
These areas are running a few degrees cooler than surrounding obs,
but still result in a pleasant fall evening with temperatures in the
upper 60s-low 70s.

Satellite also shows a continuous cloud band from northern Ontario
to Texas, marking the frontal zone that extends from the occluded
Hudson Bay low. This front has made little eastward progress today,
but will eventually get redirected equatorward across Lower Michigan
tonight/Tuesday as a surface high expands across the northern tier
states. Radar returns have decreased throughout the day with the
influx of a dry slot aloft and bifurcation of low level moisture
transport. This is on par with model trends, which support a dry
fropa Tuesday. Remnant cloud cover is expected to accompany the
frontal passage, but should be transient/shallow enough to allow for
some patchy fog development Tuesday morning. Cold advection will not
peak until Wednesday, but still expect to see a thermal gradient
from the Saginaw Valley (highs in the upper 60s) to the Ohio border
(highs in the mid 70s).

Conditions will be strongly influenced by the evolution of the upper
level ridge as the week wears on. The ridge will transition from its
current broad/flattened state into an amplified trough-ridge pair by
the end of the work week as northern stream waves carve into New
England. Locally, this results in mid-level height falls and a
southern shift to the jet stream that directs weak forcing across
the Great Lakes Wednesday morning. Moisture struggles to stay in
tact as it encounters the much drier surface high over the Great
Lakes. This high effectively stalls theta-e advection well west of
the state to limit QPF locally to a few hundredths of an inch
Wednesday morning. The thermal gradient follows a similar pivoting
pattern, with SE MI in the path of the thermal trough. Temperatures
on Wednesday only make it into the low 60s as a result.

Dry weather follows to close out the work week, followed by an
unsettled pattern this weekend as the upstream theta-e ridge
releases eastward in tandem with strong low pressure. Majority of
ensemble members generate measurable 24-hour QPF amounts Friday-this
weekend with a general warming trend anticipated.

&&

.MARINE...

Mostly dry cold front tracking through the Central Great Lakes this
evening. Northwest winds will gradually increase tonight and Tuesday
behind the front as colder air slowly filters into the region. The
coldest air will arrive early Wednesday morning, as 850 MB temps
drop into the low to mid single numbers. Winds will be out of the
northeast at this time as large high pressure builds through the
northern Great Lakes. With northerly sustained winds around 20 knots
Tuesday night, the prolonged long fetch will likely be enough to
build waves at or above 4 feet over the southern Lake Huron Basin.
Winds to then become light and variable to end the work week as the
high pressure system becomes fully entrenched.

&&

.PREV DISCUSSION...
Issued at 1233 PM EDT Mon Oct 13 2025

AVIATION...

Early morning low level moisture is resulting in an expanding diurnal
cu field early this afternoon, more concentrated east of the
terminals. Some degree of diurnal cu will persist through the
afternoon. Growth of the daytime boundary layer should keep these
clouds VFR based this afternoon. The region of showers ongoing
across Lake Michigan is associated with a weak cold front. This
frontal system will undergo considerable weakening as it advances
across Se Mi tonight. This will ensure a dry fropa with limited
cloud cover. The low level flow will turn more northerly overnight,
limiting the degree of inland advancement of the marine layer. This
will inhibit a more widespread and prolonged early morning fog
event. With current surface dewpoints in the 50s and the potential
for intervals of clear skies amidst a light wind field overnight will
support some radiational fog development.

For DTW/D21 Convection...No thunderstorms through the taf period.

DTW THRESHOLD PROBABILITIES...

* Low for visibilities aob 1/2 sm or ceilings aob 200 ft early
Tuesday morning.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory from 5 PM Tuesday to 5 PM EDT Wednesday for
LHZ421-441>443.

Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

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


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