860
FXUS63 KDTX 072301
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
701 PM EDT Fri Jun 7 2024

.KEY MESSAGES...

- Decreasing wind this evening and decreasing clouds tonight into
Saturday morning.

- Showers return quickly mid to late Saturday afternoon and spread
across the area Saturday night. A rumble of thunder is possible
south.

- A stray shower is possible Sunday with a weak cold front leading
to slightly below normal temperatures Monday.

- Cool early week conditions are followed by a warming trend back
into the 80s by late week.

&&

.AVIATION...

There will be a decrease in lingering MVFR based clouds during the
early evening due to both the loss in daytime heating and slow
departure of the mid level moisture to the east. Winds speeds will
also decrease to under 10 knots this evening as diurnal mixing
ceases and a weakening of the sfc gradient ensues. Generally
tranquil aviation conditions will then hold into early Saturday
afternoon. A mid level short wave will then drive rain across Se Mi
from late Sat aftn into the evening. Ceilings are expected to be VFR
upon the arrival of this rain. Model guidance would suggest
increasing chances for MVFR conditions toward Saturday evening as
the low levels moisten.

For DTW/D21 Convection...Very little instability is expected with
the short wave Saturday aftn/evng, so thunderstorms are not
expected.

 DTW THRESHOLD PROBABILITIES...

* Low for ceilings aob 5000 feet Saturday afternoon. High Saturday
  evening.

&&

.PREV DISCUSSION...
Issued at 358 PM EDT Fri Jun 7 2024

DISCUSSION...

Breezy and cool conditions continue for the balance of today and
this evening around the south flank of broad northern Ontario low
pressure. Afternoon radar and satellite data indicate a favorable
tendency for light showers toward the Tri Cities and northern Thumb
but still just spotty coverage. This is associated with a smaller
scale wave sliding across Lower Mi providing localized forcing along
with peak daytime heating within the larger scale mid level cold
pool. Model analysis fields also show a mid level short wave ridge
across the Midwest set to follow across the Great Lakes late tonight.
A rapid subsidence transition then leads to decreasing clouds with a
weak surface high pressure reflection through Saturday morning.
Westerly surface wind holds around 5 knots to prevent full
radiational cooling for low temperatures around 50 by sunrise,
slightly below normal for early June.

An equally rapid transition back to a pattern of showers occurs
later Saturday through Saturday night as Plains low pressure moves
into the Midwest and Great Lakes. Today`s 12Z models are in good
agreement on a plume of mid level moisture returning into Lower Mi
ahead of the surface wave with slightly faster onset timing Saturday
afternoon rather than by Saturday evening compared to earlier
forecast cycles. The faster timing is tied backing flow ahead of the
mid level wave and associated DCVA driving increased isentropic lift
and theta-e advection, although with still anemic instability for low
thunderstorm potential. The 12Z HREF run exhibits both near zero
surface based and MUCAPE as the surface wave and weak cold front move
across the region and exit eastward by sunrise Sunday morning.

The Saturday night wave transitions the large scale mid level
pattern away from the uncommon west to east configuration to more of
a trough-ridge-trough set up Sunday into Monday. This results in
reinforcement of cool air into the Great Lakes with another front
moving down from Canada Sunday afternoon and night. The latest model
data is again in reasonable agreement on mid afternoon timing which
allows temperatures a chance to rise into the lower 70s before
clouds thicken with a stray shower late in the day. The inherited
borderline slight/chance POPs are preferred and maintained in this
forecast cycle. The bulk of the cool air reinforcement then arrives
Sunday night in time to start Monday out with another round of below
normal readings in the 60s.

MARINE...

Winds weaken overnight to generally below 20kts as broad low
pressure over northern Ontario shifts further east. Weak low
pressure swings into the southern Great Lakes Saturday bringing
widespread showers though little to no increase in westerly flow is
expected. Winds shift northwesterly following this system as
deepening low pressure over western Quebec results in tightening of
the local gradient. Wind gusts between 20-25kts likely over the bulk
of the central Great Lakes throughout the day Sunday. Areas of
potential overachievement with gusts potentially nearing 30kts are
the Saginaw Bay due to the warmer waters and subsequent more
unstable thermal profile, as well as northern Lake Huron given the
favorable fetch. Lighter winds (10-20 knots) then arrive by Monday
as high pressure builds overhead. This high remains in place for the
first of half of the work week.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...Small Craft Advisory until 8 PM EDT
this evening for LEZ444.

&&

$$

AVIATION.....SC
DISCUSSION...BT
MARINE.......KDK


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