Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 281031
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
631 AM EDT Thu Mar 28 2024

.KEY MESSAGES...

- Cooler, drier weather continues through Thursday.

- Temperatures return to around or slightly above average Friday
  into early next week.

- Next chances for rain look to arrive Saturday.

&&

.AVIATION...

The plume of clouds which streamed across Se Mi overnight are now
exiting to the east. Recent satellite data is showing some
additional clouds developing off southern Lake Michigan. In light of
the ambient dry air, the expectation is for these to generally erode
with the onset of daytime heating late this morning. This will leave
generally clear skies today. Daytime growth of the mixed layer will
result in a modest uptick in the WSW winds as 15 to 20 knot winds
will be in the mixed layer.

.DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 250 AM EDT Thu Mar 28 2024

DISCUSSION...

SE MI remains on the southern fringe of an arctic airmass as upper
troughing holds across the central Great Lakes. While the airmass is
thermally unchanged from Wednesday, 850mb temps holding around -7C,
last remnants of low level moisture from the system earlier this
week were stripped out by last evening (28.00Z KDTX RAOB sounding
had PW of 0.17"). This in combination with continuing subsidence
from broad surface high pressure over the Mississippi river valley
leads to mostly sunny to sunny skies today with any cloud coverage
confined to passing cirrus. Ample insolation is still expected to
overcome the colder start with forecast highs in the upper 40s to
around 50 for the southern half of the region. Northern areas more
favored towards mid 40s owing to closer proximity to the core of the
airmass.

Low amplitude ridging currently over the Plains eventually builds
into the Great Lakes Friday shunting troughing to the Northeast.
Given more zonal nature of the ridge, WAA into southern lower MI
won`t be particularly strong, though still sufficient to bring 850mb
temps back into the low/mid positive single digits (C)- which are a
few degrees above normal for late March (average is around 0C). With
clear skies still likely in place, Friday`s highs push into the 50s
for nearly all of the area, save for the Thumb, with southern areas
having potential to reach well into the mid 50s.

Midlevel shortwave riding along the ridge is set to reach the
southern Great Lakes/Ohio Valley early Saturday. While certain
aspects of this system are in good model agreement: narrow ribbon of
stronger isentropic ascent supported overall by a ribbon of Gulf
moisture pulled north along the Mississippi; exact track and
broadness of the circulation still carry a fair amount of
uncertainty. Trends have favored a slightly more diffuse parent PV
anomaly resulting in a broader region of weak ascent/light precip-
offering rain chances for the majority of SE MI daytime Saturday.
However, the surface low track has trended further over IN/OH which,
should these outcomes hold, would keep the best isentropic ascent
and subsequent higher rainfall amounts likewise south of the state
line. While still a moving target, latest NBM looks reasonable based
on current solution space with PoPs lowered to chance (40-50%) for
all SE MI outside of areas near the state border which still carry
likelies (~60%).

System vacates the region overnight Saturday allowing for a drier,
still mild, finish to the weekend Sunday. Active pattern looks to
make a return Monday into Tuesday as the lingering baroclinic zone
draped across the Midwest and Ohio Valley/southern Great Lakes
activates in response to a potent Pacific mid-upper trough ejecting
out of the Intermountain West into the Plains.

MARINE...

High pressure builds in across the southern and western Great Lakes
today which maintains a southwest wind direction across the central
Lakes. Wind speeds will be mainly around 10 to 15 knots but the
southwest fetch down Saginaw Bay will produce locally higher winds
up to around 20 knots there. The high pressure maintains control
through the late week until the next low pressure moves through on
Saturday, bringing rain and snow to parts of the region. At this
time winds look to stay below marine headline criteria, but a shift
to more of a northerly direction will likely accompany the system.

&&

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

$$

AVIATION.....SC
DISCUSSION...KDK
MARINE.......TF


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