Expert Forecast Opinion

120
FXUS63 KDTX 072233
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
633 PM EDT Sat Sep 7 2024

.KEY MESSAGES...

* Cool night ahead with minimum temperatures in the upper 30s to
lower 40s most areas.

* A gradual warm up and drier stretch of weather is expected for
the upcoming week with highs back into the mid 80s by midweek.

&&

.AVIATION...

Dry and stable conditions will exist tonight as high pressure
settles across the midwest. Fading diurnal cu field this evening,
leaving a clear sky for the overnight period. Lingering gustiness to
prevailing northwest wind steadily decreases in frequency through
the evening. Daytime heating again yields a standard increase in VFR
diurnal cu Sunday. Winds back slightly to a westerly direction, with
a modest increase in gustiness tied to improving mixing depth during
the afternoon.

For DTW/D21 Convection...No thunderstorms are forecast through the
TAF period.

DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 307 PM EDT Sat Sep 7 2024

DISCUSSION...

Main lake effect shower banding over the Thumb earlier in the day
has shifted well east and continues to impact portions of southeast
Ontario. Any remaining sprinkles will fade this afternoon into this
evening as high pressure begins to build into the area skies make a
steady transition from mostly cloudy to mainly clear. With clearing
skies (and lighter west to southwest winds), temperatures will drop
notably overnight with upper 30s to lower 40s expected.

Temperatures begin to rebound on Sunday as the upper low pressure
shifts to the east With H85 temperatures approaching 10C by late
Sunday, expect highs back into the 70s most locations by afternoon.
A modest potential vorticity reservoir then pivot through northern
Ontario and clips the Lake Huron vicinity on its way into southeast
Ontario and Quebec. This may bring a few showers to parts of the
area early Monday, particularly the Thumb region. Temperatures will
continue to warm as this feature shifts east quickly and upper level
heights builds as upper ridging shifts in from the west. Expect 80
degree readings on average.

A warm and dry period will then become established for the balance
of next week and most likely into next weekend as this upper level
ridge becomes the dominant feature over the central Great Lakes.
High temperatures in the mid/upper 80s will be common during this
extended period with little/no chance of rainfall.

MARINE...

A cold-core low continues to govern conditions across the central
Great Lakes through the rest of today and tonight. Steep low-level
lapse rates generate instability over the warm waters which
maintains potential for a few additional scattered showers and gusty
winds. Still cannot rule out waterspout activity given 20C lake to
850 mb temperature difference and 25 kft convective cloud depths.
Small Craft Advisories remain in effect through this evening for the
southern Huron nearshores before gradient winds gradually diminish
as the low turns northwestward over Quebec. Wave height recovery
lags by several hours, thus the advisories shall continue through
the overnight hours. Winds become more zonally oriented Sunday as an
eastern Plains surface ridge builds eastward through the central
waterways in the wake of the departing low. Modeled pressure
gradient exhibits signs of stubbornness over Lake Huron along the
interface of the competing systems, thus an extension of the Small
Craft Advisory will be considered during the evening forecast
update. High pressure centers over the Ohio Valley Monday while a
weak shortwave crosses The Straits and shears out. This supports the
backing/weakening of flow toward southwest through mid-week with
mainly dry and mild conditions affording more favorable conditions
for watercraft.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 10 PM EDT this evening for MIZ049-055-
063.

Lake Huron...Small Craft Advisory until 5 AM EDT Sunday for LHZ421-422-441>443.

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

$$

AVIATION.....MR
DISCUSSION...DG
MARINE.......KGK/DG


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