947
FXUS63 KDTX 062322
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
722 PM EDT Sat Jul 6 2024

.KEY MESSAGES...

- Isolated showers remain be possible this evening, generally north
of I-94. Some rumbles of thunder cannot be ruled out.

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

- Hot Monday with highs in the upper 80s. Shower and thunderstorm
chances return Monday and Tuesday.

&&

.AVIATION...

We are still dealing with isolated pop up showers. As we continue to
lose diurnal heating, these showers will gradually dissipate.
Tonight into Sunday morning, look for winds to become light/variable
and/or calm as high pressure continues to slowly moves into the
region. Could see another round of BR or HZ develop tonight.
However, probabilistic data is not overly excited at seeing vsbys
fall below 3-4SM. Sunday will feature light westerly winds, with the
development of lake breeze boundaries that will bring wind shifts
late in the day to KDET/KDTW/KYIP/KMBS.

For DTW/D21 Convection...Widely scattered showers will dissipate
around/shortly after sunset.

DTW THRESHOLD PROBABILITIES...

* Low for ceilings at or below 5000 ft late tonight and on Sunday.

&&

.PREV DISCUSSION...
Issued at 346 PM EDT Sat Jul 6 2024

Pop up showers remain a consideration through tonight. Temperatures
have creeped up into the mid-to-upper-70s across the CWA today.
Isolated showers have already begun to develop, and further
development is expected throughout the evening. The best chances for
showers remains north of I-69, where CAPE values of 500 J/kg are
currently in place. 0-3km lapse rates of 7 C/km are the most
favorable ingredient for shower development currently, and not much
else supports anything more organized. CAPE values are not expected
to increase through the evening, and low shear values are a problem
for updrafts trying to organize further. PWAT values struggle to
reach 1", and showers that do develop are not expected to bring more
than a few hundreths of an inch. Warmer air at the 600mb level will
advect in this evening and bring lapse rates of around 5 to 5.5
C/km, below the moist adiabatic lapse rate and as a result, cutting
off convective access to the upper levels. With updraft potential
limited to the lower levels of the atmosphere, thunder is not
expected with these showers. However, an isolated rumble of thunder
cannot be ruled out.

High pressure ridge fills in briefly on Sunday keeping dry
conditions and few to scattered clouds through the day. As a result
temperatures will reach the 80s across the CWA tomorrow with urban
areas likely to push 85 degrees or better. The next chance for rain
comes Monday ahead of a weak front that will pass through. The
combination of frontal forcing and daytime heating will produce
decent chances for showers and storms. Hi-res models remain out of
range at this time, but looks from global models resolve CAPE values
between 1000-1500 J/kg. Trough axis will line up as well and place a
jet streak over the lower peninsula, giving the area a shot at some
decent speed shear of 30-40 knots.

Beyond Monday, models struggle to convincingly resolve rain chances
through the rest of the week. One of the main disagreements in the
deterministic models is the evolution of the negatively tilted
trough through the week. The ECMWF for example, keeps the trough
axis slightly further to the northwest than models like the GFS.
This is especially important when considering the potential for the
remnants of Tropical Storm Beryl to be picked up and brought over
the southern part of the CWA. Regardless of if Beryl makes its way
over the area or stays to the southeast, the setup will allow for
warm, moist air to advect in, pushing dew points into the upper
60s/low 70s and PWATs up to 2 inches. As a result, available
moisture in combination with daytime heating still provide chances
for showers to pop up in the mid-to-late week time frame even if the
more robust system stays to the southeast.

MARINE...

Light winds and low waves accompany the weak pressure gradient in
place through this weekend. Apart from a stray shower this afternoon
or early evening, dry conditions will prevail through Sunday as an
area of weak high pressure builds in over the Ohio Valley. Southerly
wind of around 10 knots then develops on Monday ahead of the next
frontal system moving in from the Midwest. This system will bring
scattered showers and storms late Monday into Tuesday as it tracks
through. Slightly cooler northerly flow follows for the mid-week.

&&

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

$$

AVIATION.....JA
DISCUSSION...BC
MARINE.......TF


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at www.weather.gov/detroit.