978
FXUS63 KDTX 060736
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
336 AM 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
  cloudy skies.

- Hot on 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, where
dry weather now prevails 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 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 tomorrow 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 are struggling 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...

Low pressure departs to the eastern Great Lakes this morning but
leaves a trailing trough that lingers over the local area much of
the day. This feature and enough moisture wrapping around the
departing system will keep scattered showers in the forecast with
potential for a few thunderstorms as well. Light northwest winds
develop today at generally 10 knots or below. The trough exits
tonight with weak high pressure moving back in through Sunday
bringing continued light winds. 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. Slightly cooler northerly
flow follows for the mid-week.

&&

.PREV DISCUSSION...
Issued at 130 AM EDT Sat Jul 6 2024

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.


&&

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

$$

DISCUSSION...AM
MARINE.......TF
AVIATION.....DG


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