233
FXUS63 KDTX 120344
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1144 PM EDT Sun Aug 11 2024

.KEY MESSAGES...

- Isolated showers today and tomorrow.

- Mostly dry mid-week with daytime high temperatures in the low 80s.

- Rain chances increase late week into the weekend.

&&

.AVIATION...

Mainly clear skies are expected overnight into Monday morning with
SCT-BKN cu/strato-cu developing Monday afternoon as a shortwave
encroaches on the area near peak heating. A few showers will also be
possible in this scenario. Westerly winds will continue, but with
less gustiness as pressure gradient diminishes into tomorrow.

For DTW/D21 Convection... No thunderstorms are expected.

DTW THRESHOLD PROBABILITIES...

*  Moderate for cigs at or below 5000 ft Monday afternoon.

&&

.PREV DISCUSSION...
Issued at 359 PM EDT Sun Aug 11 2024

DISCUSSION...

Cool thermal trough remains over the region with the center of the
mid/upper level closed low moves eastward just north of Lake
Ontario. As this low moves further out of the central Great Lakes,
the weakly forced cyclonic flow containing widely scattered light
showers will target mainly the Thumb region this evening.
Diminishing shower chances with a decreasing cloud trend from west
to east during the overnight. Lows by early tomorrow morning fall
into the low to mid 50s for most locations.

Lower level temperatures gradually moderate tomorrow helping bring
daytime temperatures up several degrees compared today with most
areas will be in the upper 70s. A few locations should achieve 80
degrees, especially across the Detroit Metro area and parts of the
Saginaw Valley. A favorably timed shortwave during peak heating
Monday will have very weak surface instability/steep low level lapse
rates to work with, which may be enough to generate isolated to
widely scattered light showers. Will introduce a 15-20% PoP, but
enough stability within the confluent northwest flow may be enough
to keep conditions dry. Similar scenario for Tuesday as models
depicting another weak shortwave diving S/SE through the central
Great Lakes with an associated weak surface reflection. Increased
low-level lapse rates and potentially some weak diurnal instability
could support another day of isolated to widely scattered light rain
showers. Will have 15-20% PoPs during the afternoon again, but
stability may very well prevent much if any precipitation.

Mid-week will see surface high pressure settle into the New England
region as ridging builds over the western Great Lakes. This will
lead to quiet weather conditions Wednesday and Thursday. Airmass
recovery is muted by the southeast flow around the high pressure at
the surface and persistent north/northwest flow aloft. Temperatures
at 925-850 mb increase only a few degrees and offer daytime highs
Wednesday and Thursday in the low 80s.

Chances increase for more appreciable rainfall during Thursday night
into the weekend, but there remains plenty of differences in the
overall evolution of the low. The difference being a more
progressive wave or if a closed upper low develops in or around the
Great Lakes and lingers. NBM paints a broad swath of medium range
PoPs from Thursday night through the weekend given the uncertainty
in the long range models. Adjustments to timing of precipitation
likely during this period as models come into better agreement.

MARINE...

The low pressure system now over Quebec will send one last trough
through the eastern Lakes today. This trough running up against the
high pressure system lifting northward into the southern Great Lakes
will keep some gustiness around this afternoon. High pressure should
win out tonight and take hold across the region which will then
persist through the first half of the week. Winds will drop off
with gusts below 15 knots through this time. There will be a slight
chance of a shower or two mainly across Lake St. Clair and Lake Erie
as diurnally forces showers drift southeast toward those bodies of
water. Otherwise a quiet forecast for the marine areas.

&&

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

$$

AVIATION.....DG
DISCUSSION...AA
MARINE.......DRK


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