483
FXUS63 KDTX 071902
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
302 PM EDT Sun Jul 7 2024

.KEY MESSAGES...

- The holiday weekend closes out with dry weather today under partly
  sunny skies.

- Warming up into Monday with highs in the mid to upper 80s. Shower
  and thunderstorm chances return Monday and Tuesday.

- Remnants of Beryl may begin to impact parts of the area by Tuesday
  night and Wednesday.

&&

.DISCUSSION...

Shortwave ridge overtop the Great Lakes has kept dry conditions in
place with some spotty cumulus clouds and temperatures currently in
the lower 80s. Dew points in the upper 50s will increase into the
low to mid 60s tonight, with overnight temperatures dropping to the
mid to upper 60s across the CWA. Winds remain light and variable
through the rest of the day today before turning southerly
overnight. Temperatures slightly warmer tomorrow barring any
overachieving cloud cover, reaching the mid 80s across the CWA and
the upper 80s in urban areas.

Chances for showers and storms return ahead of a frontal boundary
moving into the area Monday. The front will progress very slowly
over the Great Lakes, leading to multiple chances for convective
showers and storms on both Monday and Tuesday. Storms hold off until
20Z Monday evening, where SBCAPE up to 1000 J/kg in the Thumb and
Tri-cities will be in place to help initialize the showers. Shear of
30-40 knots alongside the frontal forcing will help sustain the
updrafts as they develop through the evening. A severe storm cannot
be ruled out at this time. Only a few hundreths of an inch are
expected, but given the scattered nature of the showers, locally
higher amounts are easily possible.

Tuesday`s chances to see showers and storms are in part dependent on
how far the front is able to progress before stalling. Convection
ahead of the front may also be stifled by slightly warmer upper-
level air mixing in and creating just enough of a cap to limit the
upward potential of the developing updrafts. Profiles on Tuesday
will have lapse rates near the moist adiabatic lapse rate throughout
the column, adding another obstacle for developing updrafts to
overcome.

The remnants of Beryl and how the system impacts southeast Michigan
will be the main focus for the middle of the week. Trough will be
slow to move eastward as it picks up the tropical system early
Tuesday morning over Texas, allowing the low pressure center to
interact with the trough`s left exit region. Upper level wave will
progress northeastward on Tuesday afternoon, bringing the remnants
of Beryl to the Great Lakes. Excessive rainfall is the primary
threat with these storms at this time range.

While yesterday deterministic models struggled to resolve the path
of the storm, today shows more convergence, specifically in line
with yesterday`s ECMWF solution. Under the assumption that the ECMWF
has the best handle on the storm, today`s solution now highlights
rain arriving Wednesday morning, the heaviest rainfall occuring
Wednesday night, and placing the track/passage of the low over
western Lake Erie Thursday morning. Too much faith cannot be placed
in any one model however, and a range of possibilities still exist.
Ensemble guidance gives mean storm total QPF amounts near an inch
but there is a large variance among the members, reinforcing that
much will depend on the exact track of the storm. At this time, a
broad 1-2 inches of rain is likely, but locally higher amounts will
be possible. Further model convergence over the next few model cycles
on storm track and timing is needed to more effectively highlight
the risks the remnants of Beryl will bring to southeast Michigan,
although it is clear that a Wednesday arrival is most likely and
that there is a threat of significant rainfall across the area.

&&

.MARINE...

Benign marine conditions prevail through tonight as high pressure
maintains control of the area. A weak frontal boundary is forecasted
to reach the western Great Lakes overnight and slowly track eastward
across the central Lakes Monday night into Tuesday. Winds on Monday
will orient out of the south ahead of this system at around 10 to 15
knots. Scattered showers and storms will accompany the system as
well from Monday into early Tuesday. Drier light westerly flow
follows on Tuesday before more active weather arrives Wednesday into
Thursday as the remnants of Tropical System Beryl move into the
vicinity. The forecast remains sensitive to the eventual track and
strength of the system, but current information suggests gusty
northeast winds and heavy rain will be possible.

&&

.HYDROLOGY...

The remnants of Beryl will move along an upper level wave and begin
to impact the Great Lakes area Tuesday night into Wednesday. The
remnant low pressure center will track overhead Wednesday night into
Thursday morning. At this time, details on the track of this system
are difficult to determine. An increased risk of heavy rainfall will
exist as the system encroaches on the area. Most of southeast
Michigan is set to receive at least an inch of rain, and if impacted
directly, rainfall will most likely reach or exceed 2 inches in some
areas.

&&

.PREV DISCUSSION...
Issued at 1236 PM EDT Sun Jul 7 2024

AVIATION...

Remnant low level moisture along/east of a KDET to KMBS line
resulted in a sct-bkn MVFR based cu field late this morning. Ongoing
boundary layer growth through diurnal mixing will support an
increase in the cloud bases to 4-6k feet during the course of the
afternoon/early evening. Otherwise, high pressure anchored across
the eastern Great Lakes will maintain light winds and will inhibit
a late day convective response.

For DTW/D21 Convection...Thunderstorms are expected across the
airspace today and tonight.

DTW THRESHOLD PROBABILITIES...

* None


&&

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

$$

DISCUSSION...BC
MARINE.......TF
HYDROLOGY....BC
AVIATION.....SC


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