620
FXUS63 KDTX 242002 CCA
AFDDTX

Area Forecast Discussion...CORRECTED...
National Weather Service Detroit/Pontiac MI
335 PM EDT Fri May 24 2024

.KEY MESSAGES...

- Showers and thunderstorms move in tonight largely after midnight
and continue into Saturday morning. An isolated storm may become
severe with strong winds or hail.

- Dry weather returns Saturday afternoon through Sunday morning.

- Showers are likely again with a chance of thunderstorms Sunday
afternoon and Sunday night.

- The Memorial Day outlook calls for cool temperatures with showers
likely Monday and Monday night.

&&

.DISCUSSION...

Active weather this Memorial Day weekend and beyond for southeast
Michigan. Many opportunities for precipitation ahead, and warmer
than average temperatures hang around for the weekend before a
cooling trend begins with the start of the week.

The main focus of the forecast for today are the storms projected to
move in overnight tonight. Due to the timing of storms passing
between 06-12Z, the storms will weaken after sunset and become
unlikely to produce severe weather due to overnight surface cooling
leading to a near-surface temperature inversion. Should a parcel be
forced upward, PWATS around 1.25-1.5 inches, MUCAPE nearing 1000
J/kg, and 30 knots of shear could potentially help sustain the
updraft and produce some rain and/or small hail. Any developing
storms are unlikely to be severe, but an isolated severe storm
remains possible. SPC keeps a general thunderstorm risk in place for
this system.

Near-zonal flow aloft behind this system briefly brings back clear
skies on Saturday behind the front. Temperatures in the upper 70s,
reaching 80 on Saturday, cooling off slightly to the mid to upper
70s Sunday. While these temperatures are only slightly above the
climatological average and are not unreasonable for this time of
year, those sensitive to heat should prepare an effective cooling
method and plan to stay hydrated for any outdoor Memorial Day
festivities over the weekend.

Widespread showers and storms return Sunday evening as a longwave
upper level trough brings a low pressure system into the area from
the southwest. The system will begin to occlude as it begins to
impact the area, so much will be determined on how far north that
occlusion point reaches. Thunderstorms and severe weather are a
possibility with this system, currently expected to move through
between 0Z and 12Z Monday. SPC gives a Marginal risk for severe
weather for the southern portion of the CWA. WPC also has a Marginal
risk for excessive rainfall on their Day 3 Outlook, meaning between
a 5-15% risk of rainfall exceeding flash flood criteria. Guidance
has yet to agree on rainfall totals for southeast Michigan, with
deterministic models ranging from two tenths to to inches, but
ensemble runs put mean QPF values just over a half inch.

As the low pressure moves out, the potential for light showers to
form exists Monday, fueled by cold conveyor belt wrapping around the
low. Temperatures continue to drop Monday as cloud cover makes
reaching the 70s difficult. Longwave trough remains in place through
the middle of the week, dropping daily high and low temperatures
into the 60s and 40s respectively, while also bringing more chances
for some minor showers caused by some shortwaves embedded within the
larger trough.

&&

.MARINE...

An upper level ridge exits the Great Lakes this evening as a low
pressure system works northward into south-central Canada. Gradient
winds take on an easterly trajectory while a strengthening low-level
subsidence inversion limits gust potential. Gusts may approach 25
knots across Saginaw Bay, but will forego a Small Craft Advisory
given the infrequency of higher gusts. A shortwave feature shearing
off the parent upper level feature to the west progresses into the
central Great Lakes tonight and Saturday morning as a secondary
surface low develops along the primary system`s cold front. This
presents an opportunity for thunderstorms and locally higher
winds/waves through Saturday morning. The strongest dynamics are
expected to depart before thermodynamic profiles become more
favorable for mechanical mixing processes, therefore no headlines
are anticipated. An occluded low then tracks across Wisconsin and
The UP Sunday night which drags a potent LLJ across the waterways.
More showers and storms are expected, some of which may be strong to
severe. Potential also exists for Small Craft Advisory conditions as
early as Sunday evening, marked by gusts approaching 30 knots and
occasional waves near 5 feet.

&&

.PREV DISCUSSION...
Issued at 205 PM EDT Fri May 24 2024

AVIATION...

VFR conditions will prevail through the remainder of this afternoon
and evening with mainly some increase high clouds during the
afternoon. Lower VFR and MVFR ceilings will arrive tonight as a
weakening system moves into southeast Michigan bringing a broken
line or more scattered showers. There remains a low potential for
thunderstorms tonight, but confidence is too low to carry thunder in
the TAFs at the time. Timing of rainfall for tonight will be between
06Z and 09Z. MVFR ceilings look probable for a period tomorrow
morning with ceilings lifting around mid morning tomorrow. Light
southeast winds today turn more southerly tonight while maintain near
10 knots sustained winds before becoming westerly tomorrow morning.

For DTW/D21 Convection...Weakening complex brings showers and
isolated thunderstorms into the airspace between 06Z and 09Z.
Confidence not high in thunderstorms being widespread enough to
include in TAFs at this time. Any thunderstorm that can maintain
strength and moves across any terminal could bring brief 30+ mph
gusts.

DTW THRESHOLD PROBABILITIES...

* Low for thunderstorms overnight tonight (~06z-09z)

* Moderate for ceilings aob 5kft by early tomorrow morning.


&&

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

$$

DISCUSSION...BC
MARINE.......KGK
AVIATION.....AA


You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.