348
FXUS63 KDTX 140733
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
333 AM EDT Sat Sep 14 2024

.KEY MESSAGES...

- Very warm and dry conditions prevail today through at least the
  middle of next week.

- Fog development will be possible early each morning.

&&

.DISCUSSION...

500mb analysis shows the resident ridge centered over northern Lake
Huron is steady at 591 dam this morning. The remnants of Francine
have stalled over the lower Mississippi Valley and local impacts
will be limited to just intervals of cirrus at times today. The
ridge maintains a subsident and stable profile with sfc high
pressure continuing to dominate local conditions. Little change to
the thermal profile compared to yesterday offers a similar forecast
today with highs in the lower to mid 80s with mostly sunny skies
after patchy morning fog mixes out. Lofted wildfire smoke continues
to gyre over the region within the anticyclone - this will remain
well above the surface and pose little threat to air quality at the
surface. Lows will settle back into the upper 50s to lower 60s
overnight into Sunday morning with another round of patchy fog
possible prior to daybreak.

Nearly identical conditions on Sunday as the upper ridge eases
southeast into the eastern Great Lakes. Slightly deeper mixing may
boost temps by a degree or two. By Monday the ridge will flatten
substantially but still hold on overhead as the remnants of Francine
merge with a coastal low off the Carolinas. The composite upper low
will attempt to progress north into the Ohio Valley through the
midweek but will be working against a very weak flow pattern and an
anomalously high geopotential height field over the eastern CONUS
and Canada. A small sample of ensemble members within the GEFS and
GEPS families continues to show some of the Atlantic moisture making
it into the local area as showers by Wednesday and Thursday, but the
majority of members continue to hold dry conditions. Even those that
do precipitate generally only produce a few hundredths of an inch.

Deep troughing becomes established over the western CONUS next week
which maintains a longwave ridge over the eastern CONUS and Great
Lakes even after the current rex block breaks down. This favors
continued above normal warmth and dry conditions through the end of
the 7 day forecast. Highs in the 80s and lows in the 50s/60s will
continue to be the norm in this pattern. Beyond this period, CPC
highlights SE MI within a 80-90% chance for above normal temps and
33-50% chance for below normal precip for the 6-10 day outlook. The
week 2 (8-14 day) outlook also leans toward above normal temps and
below normal precip.

&&

.MARINE...

Central Great Lakes holds under the influence of high pressure
through the first half of next week. This maintains dry conditions
and generally light flow across the region though some gusts near
20kts will be possible over Lake Erie as the remnants of Francine
tighten the gradient over the Ohio Valley and far southern Great
Lakes.

&&

.PREV DISCUSSION...
Issued at 1158 PM EDT Fri Sep 13 2024

AVIATION...

Expansive area of high pressure maintains influence this period,
ensuring VFR with cloud free conditions outside of intervals of
cirrus. Position and strength of the high maintains a modest flow
from a southeast to easterly direction. Forecast will continue to
highlight a brief window for MVFR level visibility restrictions in
shallow fog around daybreak.

For DTW/D21 Convection... Thunderstorms are not in the forecast for
the foreseeable future.

 DTW THRESHOLD PROBABILITIES...

* None.


&&

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

$$

DISCUSSION...TF
MARINE.......KDK
AVIATION.....MR


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