139
FXUS63 KDTX 051724
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
124 PM EDT Sun May 5 2024

.KEY MESSAGES...

- Decreasing clouds this afternoon and evening. Mostly sunny Monday.
Seasonal temperatures.

- Showers likely with a chance of thunderstorms Tuesday afternoon
and evening. Strong to severe storms are possible south of I-94.

&&

.AVIATION...

Weak secondary cold front slowly sagging south through the TAF
corridor this afternoon maintaining MVFR cloud cover as well as
areas of drizzle. While clearing has already occurred over MBS,
satellite trends show lower cloud gradient has stubbornly held north
of FNT thus far. Based on these trends and forecast soundings, have
gone a bit more pessimistic on lifting/clearing timing for all TAF
sites (save for MBS) pushing it back to evening (~21-00Z). High
pressure becomes fully established over the region tonight setting
up lighter (10kt or less) flow as well as limiting any redevelopment
of lower cloud, once clearing occurs.

For DTW/D21 Convection... Low level moisture has held more
stubbornly even with drier air drawn into the area. Pushed
lifting/clearing timing to late evening-early tonight (~00-05Z)
though this still carries a fair degree of uncertainty.

DTW THRESHOLD PROBABILITIES...

* High for ceiling 5000 feet or less through this evening, turning
  low tonight (between ~03-06Z).

&&

.PREV DISCUSSION...
Issued at 301 AM EDT Sun May 5 2024

DISCUSSION...

Showers and isolated thunderstorms weakened and decreased in
coverage as they inched toward Se Mi early this morning, the result
of the upper jet support and mid level height falls lifting north of
the forecast area. The convection also become outflow dominated,
leading to waning instability. The associated surface front will
also weaken as it exits east of the area this afternoon, although
the 00Z hi res suite all indicate lingering sfc troughing extending
across Se Mi into late afternoon. Sfc high pressure will expand into
the western Great Lakes today as mid level ridging builds across the
upper Mississippi Valley. Ample low level moisture along/ahead of
the approaching front (sfc dewpoints around 60F) will contribute to
low clouds and a few lingering showers this morning. Low level cold
air advection this afternoon will deepen the mixed layer, boosting
cloud bases and supporting afternoon highs well into the 60s to low
70s. Persistent low level anticylonic flow associated with the
inbound sfc high will eventually drive drier air into Se Mi, leading
to a late afternoon/evening clearing trend from north to south. The
associated north-northeast sfc winds will also advect the Lake Huron
marine layer inland during the course of the afternoon/evening. This
will present itself as a notable drop in temperatures.

Mid level ridging and associated sfc high pressure will be anchored
over Lower Mi and Lake Huron by Monday. Occasional high clouds may
be all that keeps skies outright clear. The strength of the
subsidence will limit mixing depths Monday to just under 5k feet,
resulting in daytime highs mainly in the mid 60s to near 70. The dry
air and light winds will allow respectable nighttime cooling, both
tonight and Monday night, leading to lows into the 40s.

A highly amplified long wave trough is forecast to emerge from
western Canada into the Central Plains Tuesday, becoming a deep
closed low across the northern Rockies/High Plains by Wednesday.
Strong deep layer southwest flow ahead of this system will drive an
instability plume into the Ohio Valley on Tuesday. Upper jet support
and strong moisture transport/convergence along a low level warm
front will support increasing chances for showers/thunderstorms Tues
aftn/Tues night. The northward extent of the surface based
instability plume into southern Michigan carries some degree of
uncertainty. While there is still a decent spread among ensemble
members, the late timing of the front and easterly flow off the
stable lakes suggests that surface based instability may struggle to
advect too far northward into Se Mi. In light of strongly sheared
environment and model uncertainty, the southern portions of Se Mi
may remain on the northern edge of the SPC severe outlooks for the
next couple days.

MARINE...

A weak cold front will continue to track east across the central
Great Lakes this morning bringing scattered showers, a few embedded
thunderstorms, and some areas of fog. Winds shift to northwest as it
departs, peaking at around 15 to 20 knots this afternoon. Conditions
dry out as high pressure builds into the area today and takes
residence through Monday and into Tuesday, maintaining light winds
and waves. A more active weather pattern follows beginning late
Tuesday as the next low pressure system sends a warm front across
the region. This system brings a period of numerous showers and
storms Tuesday night through early Wednesday with another system
likely to follow for Thursday. At this time winds are likely to
remain below marine headline criteria.

&&

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

$$

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


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