199
FXUS63 KDTX 192227
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
627 PM EDT Tue Aug 19 2025

.KEY MESSAGES...

- Seasonable temperatures and dry weather move in and hold Wednesday
through Friday.

&&

.AVIATION...

Residual shallow convection/showers will continue to exit east of
metro Detroit, with the risk of additional showers ending by TAF
issuance. A cold frontal passage now advancing across Detroit will
support shallow cool air advection during the night. Ample post
frontal low level moisture will sustain a low stratus deck through
the night. Available guidance along with observational trends
suggest prevailing low end MVFR and IFR ceilings. The post frontal
northerly gradient will sustain winds around 10 knots through the
night and will hinder fog development. While it is possible that
some patches of drizzle may develop, which would support some
reductions in visibility, confidence is not high enough to include
in the terminals. Continued dry air advection and diurnal
heating/mixing will result in a steady improving trend in ceiling
heights during the day Wednesday.

For DTW/D21 Convection...Shallow convection (mainly showers) will
exit the far southeastern portion of the D21 airspace around/shortly
after TAF issuance. No convection will occur through the remainder
of the TAF forecast period.

THRESHOLD PROBABILITIES...

* High for ceilings aob 5000 feet tonight and Wednesday.

&&

.PREV DISCUSSION...
Issued at 314 PM EDT Tue Aug 19 2025

DISCUSSION...

Strong upper level anticyclonic wave break over the Canadian Prairie
provinces combined with weak entrance region dynamics over
Ontario/Quebec is resulting in the amplification and digging of a
trough over the Great Lakes region today. The greatest area of the
height falls and synoptic scale ascent has now been squeezed
immediately south and east of the cwa. Will still have to work
through an axis of showers and convergence that is now pushing into
northern Metro Detroit. Radar data supports warm cloud/small droplet
distribution in the showers. No thunderstorms are expected, but
rainfall rates could prove to be surprisingly efficient the couple
of hours. Model data the past 24 hours or so has steadily converged
on a solution that is much drier for the evening hours. Will continue
chance PoPs.

The midlevel trough is forecasted to be progressive, opening the
doors to differential geopotential height rises tonight. While the
large scale upper level pattern supports blocking over the Southwest
United States, tilting of the  upper level ridge into the Great
Lakes is anticipated. The net result will be a uniform expansion of
surface high pressure into Southeast Michigan with the anticyclone
then persisting through the early portion of Saturday. More
comfortable weather is expected with highs generally in the lower
80s (around normal) with surface dewpoints in the 50/60s.

The next chance of rainfall is expected to be late Saturday and
Sunday. There has been a strong consensus amongst the global models
in amplifying a large wavelength upper level low pressure system as
it pushes east of he Rocky Mountains. Current forecast suggests
daytime high temperatures in the low 70s Next Monday and Tuesday,
approximately  8 to 10 degrees below normal.

MARINE...

Low pressure reaches western Lake Erie late this afternoon and
continues to track east toward Lake Ontario tonight. Showers with
embedded thunderstorms will wane in coverage through the evening
while wind over Lake Huron backs from east to northeast, increasing
to around 15 to 20 knots with gusts to 25 knots on Wednesday. Small
Craft Advisories are in effect for all southern Lake Huron nearshore
zones through Wednesday evening. High pressure builds in from the
northern Great Lakes through Thursday causing northeast wind to
become light. Wind then shifts to southwest on Friday ahead of the
next cold front set to arrive on Saturday.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement from Wednesday morning through Wednesday
     evening for MIZ049-055-063.

Lake Huron...Small Craft Advisory from 8 AM to 10 PM EDT Wednesday for LHZ421-
     422-441>443.

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

$$

AVIATION.....SC
DISCUSSION...CB
MARINE.......TF


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