596
FXUS63 KDTX 060530
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
130 AM EDT Sat Jul 6 2024

.KEY MESSAGES...

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

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

&&

.AVIATION...

We are already starting to see haze develop behind the exiting line
of showers and thunderstorms. With dewpoints still well into the low
to mid 60s and calm winds expected overnight, confidence is growing
that we will see haze develop. Soundings are not overly excited
about seeing any fog development, as passing mid and high clouds
overnight should help limit temperatures from fully bottoming out.
Around/near daybreak on Saturday, expect MVFR ceilings to develop
around 2.0-2.5kft. It remains possible that we could see low-end
MVFR ceilings, but for not opted to hold off on mentioning any BKN-
OVC cloud decks and just kept SCT mentions of this potential. By
late Saturday morning and into the afternoon hours, widely scattered
showers and perhaps a thunderstorm or two will be possible. Given
the coverage is is very difficult to pinpoint a solid TEMPO period.
So will let subsequent TAF updates refine that potential, if needed.

For DTW/D21 Convection...Widely scattered showers and a thunderstorm
or two are expected on Saturday.

DTW THRESHOLD PROBABILITIES...

* Low for thunderstorms on Saturday.

* Medium for ceilings at or below 5000 ft on Saturday.

&&

.PREV DISCUSSION...
Issued at 311 PM EDT Fri Jul 5 2024

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.

&&

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

$$

AVIATION.....DG
DISCUSSION...SC
MARINE.......TF


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