603
FXUS63 KDTX 051911
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
311 PM EDT Fri Jul 5 2024

.KEY MESSAGES...

- Lingering isolated strong to severe thunderstorms remain possible
this evening.

- The low pressure system lingers over the Great Lakes tomorrow
keeping a chance of showers and thunderstorms in the forecast.

- The holiday weekend closes out with dry weather Sunday under
partly sunny sky.

&&

.DISCUSSION...

A compact mid level low across Wisconsin this afternoon will
traverse the straits tonight before lifting north of Lake Huron on
Saturday. Cloud cover expanded across much of Se Mi today within the
entrance region of an upper jet. Areas of light showers/sprinkles
and an early convective release has limited available instability
over most of the area with the exception of the Saginaw Valley. An
additional Short wave impulse pivoting around the upper trough and
entrance region upper jet support will keep some focused ascent
across the Saginaw Valley and points north this evening. This will
be the most probable locations for additional late day deep
convection. ML Cape Values hovering around 1k J/kg and 0-6km shear
values of 40-50 knots may still support isolated strong/convection.

The upper low will transition to an open wave as it exits to the
northeast on Saturday. Reasonable model agreement indicates a
trailing trough axis advancing from northeast Lower Mi into the
Saginaw Valley/thumb regions by late afternoon. This added boundary
layer convergence within weak instability will support a chance for
deep convection late Saturday across the north. Low level thermal
profiles will be cooler tomorrow (925mb temps a few degrees cooler).
This and the expectation for some cloud cover (morning low clouds
transitioning to sct-bkn diurnal cu field) will support highs in the
70s.

Sunday into Monday, Se Mi will lie between a low level anticylone
across the eastern Great Lakes and brad mid level troughing across
the upper Midwest/western Great Lakes. The proximity to the
anticyclone will keep convective chances low at least through mid day
Monday. Persistent southwesterly flow will drive warmer air into Se
Mi, supporting highs well into the 80s Sunday and near 90 Monday. An
eastward progression of the long wave trough will support increased
chances for convection late Monday into Tuesday, with slightly
cooler temps expected in its wake by mid week.

&&

.MARINE...

Low pressure tracks across Lower Michigan this evening and into Lake
Huron tonight with scattered showers and thunderstorms continuing to
track east to northeast at around 30 knots. Isolated storms may be
severe, capable of producing wind gusts in excess of 35 knots, hail,
and waterspouts. Showers and storms will decrease in coverage and
intensity tonight with light wind shifting to northwest as the low
departs and sends a weak cold front through. Isolated to scattered
showers linger into parts of Saturday as troughing is slow to
release from the region. Light winds continue into Sunday with
sunnier skies as a weak ridge of high pressure builds in from the
south. Southerly wind of 10 to 15 knots then develops on Monday
ahead of the next frontal system moving in from the Midwest. This
system will bring showers and storms late Monday into Tuesday as it
tracks through.

&&

.PREV DISCUSSION...
Issued at 216 PM EDT Fri Jul 5 2024

AVIATION...

Ample amount of shear and CAPE exist to sustain scattered
thunderstorms this afternoon and late evening. Several storms have
already developed INVOF MBS along a convergence boundary while
thunderless showers crop up over the Metro Detroit terminals.
Expectation is that most thunderstorm activity will hold off until
late this evening for FNT south, thus the later TEMPO group
adjustments. Clouds are largely expected to remain high-based, but a
brief BKN high-MVFR ceiling could arise early this afternoon. Light
to modest southwest winds drop-off overnight with some HZ
reintroduced Saturday morning. Potential exists for low-MVFR
ceilings/visibilities overnight, but not confident enough for
inclusion for the 18Z TAF cycle. Borderline MVFR ceilings should
settle in Saturday morning with stratus favored amidst the cooler
post-frontal airmass.

For DTW/D21 Convection...Scattered showers are expected this
afternoon along a pre-frontal trough with storms more likely to
develop this evening ahead of an inbound cold front. Will highlight
the earlier period with -SHRA then target the late evening (01-04Z)
period for thunder. Storms will generally be single cellular or
multicellular with SW-NE storm motion.

DTW THRESHOLD PROBABILITIES...

* Low for thunderstorms between 18Z and 22Z today, then medium
  between 01Z and 04Z this evening.

* Low for ceilings at or below 5000 ft this afternoon then medium
  late tonight into Saturday.


&&

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

$$

DISCUSSION...SC
MARINE.......TF
AVIATION.....KGK


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at www.weather.gov/detroit.