748
FXUS63 KDTX 061903
AFDDTX

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

.KEY MESSAGES...

- Isolated to widely scattered showers will be possible this
afternoon and 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.

&&

.DISCUSSION...

A cold front has cleared the state as of early this morning, and
outside of spotty showers over central Michigan, most locations are
dry in the wake of the front with temperatures presently in the mid-
60s. Residual moisture and humidity will hold on today across SE MI,
which will aid in the production of isolated to widely scattered
shower activity. The inherited forecast looks reasonable, holding
PoP chances generally north of I-94, with highest PoP chances (30-
35%) located along and north of I-69, tied to the greater moisture
and subsequently better instability.

Instability and bulk shear are not favorable for sustainable
activity today, holding at 500 J/kg and around 15-20 knots
respectively. Additionally, a cap just under h600 will limit
convective depth and coverage. However, steep low level lapse rates
with the passage of multiple upper-level waves do justify the PoP
potential. Cannot rule out some embedded thunderstorms, but LI
values of 0 to 1 and very poor mid-level lapse rates favor rain
showers. Shower and storm potential will wane with the loss of
daytime heating, with lingering potential lasting through 10PM-
Midnight. Highs hold in the upper 70s in the wake of the front.

A weak shortwave ridge will fill in behind the departing shortwave
and will bring a day of dry weather with temperatures returning into
the mid 80s for a high. The return of warmer weather is a result of
multiple upper-level waves that fill in over the Plains with trough
amplification taking place across the greater Plains through the
early week period. Initially, this directs heat and moisture from
central US downstream into the Great Lakes noted by h850
temperatures increasing from 16C Sunday evening to 18C by Monday
evening. This brings daytime highs in the upper 80s, possibly
reaching 90 across urban areas on Monday. Rain and thunderstorm
chances are also possible Monday with the improved moisture and
support from glancing shortwaves ahead of the main trough axis. The
better chances for numerous to widespread showers with embedded
thunderstorms will enter late Monday into Tuesday tied to the better
connection with the trough, with the axis swinging over Michigan
late Tuesday night.

Medium range models are more muddled through the midweek period
given subtleties with shortwave passages and interactions. One major
consideration that models will struggle with this far out will be
the upstream impacts of Tropical Storm Beryl. The latest ECMWF is
much less progressive relative to the 12Z model run and pushes the
system into the Ohio Valley, clipping portions of SE MI. Even less
progressive is the ICON (and ICON-EPS), which pushes the center of
the low right over Michigan. Regardless, not much credence is given
into any one particular model solution at this time factoring in
limited sampling from the upper-air network, but it is worth noting
as several deterministic runs display a much less progressive
solution for the 00 cycle. Closer attention will be given to the
path of the system as it makes landfall somewhere over southeast TX
by early Monday.

&&

.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.

&&

.PREV DISCUSSION...
Issued at 214 PM EDT Sat Jul 6 2024

AVIATION...

Early day stratus lifted and mixed out leaving mostly VFR cu around
for the afternoon.  Could see a few cigs still dipping to 2500-
3000ft for a bit before finally mixing out for good here in the next
hour or two. We then look to this afternoon into the evening hours
where the trough draped across Mid MI tries to initiate showers and
thunderstorms. There have been some very small isolated showers
popping up already but all very short lived as the upper levels of
the atmosphere are not favorable for longer lived cells. I left any
mention of showers/thunderstorms out of the tafs as there isn`t a
clear signal for any taf site to make a mention. Best chances appear
to be PTK and FNT due to the current activity, when models showing
MBS having better chances this evening. We`ll monitor and amend
when necessary. Chances of thunderstorms appear low due to short
duration of the showers and unfavorable upper levels of the
atmosphere. Dewpoints hanging around 60 degrees and any rain that
occurs will make fog possible again tonight.

For DTW/D21 Convection...Widely scattered showers and a thunderstorm
or two will be possible this afternoon/evening, but best chance will
hold north of KPTK.

DTW THRESHOLD PROBABILITIES...

* Low for thunderstorms this afternoon.

* Medium for ceilings at or below 5000 ft this afternoon.


&&

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

$$

DISCUSSION...BC
MARINE.......TF
AVIATION.....DRK


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