866
FXUS63 KGRR 060525
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
125 AM EDT Thu Jun 6 2024

.KEY MESSAGES...

- Clearing this evening, then showers/storms tonight

- Scattered showers and cooler Thursday

- Cooler Weekend With Some Showers Possible

&&

.DISCUSSION...
Issued at 915 PM EDT Wed Jun 5 2024

- Clearing this evening, then showers/storms tonight

A cold front is currently moving across Lake Michigan and will
sweep across the cwa later this afternoon/evening. Ahead of it,
showers and thunderstorms developed as expected within an
environment characterized by SBCAPE 2500 j/kg but only 25-30 knots
bulk shear. The less than robust shear is likely holding back the
storms from developing further. Radar shows a well defined MCV
moving northeast into southern Calhoun County. This MCV is running
out of real estate to produce stronger storms and the event may be
over before it gets going. Quite a bit of high clouds likely
prevented further destabilization that might have otherwise overcome
the weak shear.

Visible loop shows the back edge of the clearing moving across the
lake and we`ll likely be back in the sunshine/clearing by early
evening.

A strong short wave will move in from the northwest tonight around
midnight. CAMs show another line of showers/isold storms
developing over Wisconsin and then moving over the lake around
05z. There`s roughly 400-500 j/kg MUCAPE to work with, so we may
see some isolated thunder, but most of the precipitation will be
showers.

- Scattered showers and cooler Thursday

As the upper low settles over Lower MI, h5 temps will fall from
minus 11c to minus 16c. Those cooler temps aloft will probably be
enough to generate some instability showers as mid level lapse
rates climb to over 7c/km across northern Lower. Areas primed for
showers would be the northern cwa, closer to the higher
instability. This will continue Thursday night too.

Highs Thursday will range from the upper 60s near US-10 to mid 70s
near I-94.

- Cooler Weekend With Some Showers Possible

Upper troughing with a closed upper low settles over the region late
in the week and through the weekend leading to cooler than normal
conditions and a few chances for light rain. 850mb temperatures fall
into the low single digits late this week leading to daytime highs
in the mid to upper 60s Friday and into the low 70s by Saturday and
Sunday. Overnight lows fall into the upper 40s to low 50s.

A few chances for rain exist through the extend as several
shortwaves ripple through the parent upper trough. Moisture will be
fairly limited, so mainly light rain is expected. Most notably the
chances for rain exist for Saturday and Sunday where some diurnal
heating supports precipitation potential with some thunder possible
Saturday afternoon/evening.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 121 AM EDT Thu Jun 6 2024

VFR through this TAF period. Showers will be moving through the
region until about 10z. The only risk for VCTS looks to be MKG for
the next couple hours or so. Will continue to monitor radar trends
as there is some elevated instability around that could help
produce some lightning near other terminals. After the showers
move out, a breezy afternoon is in store with gusts to 25 kts or
even a bit higher.

&&

.MARINE...
Issued at 246 PM EDT Wed Jun 5 2024

A Small Craft Advisory and Beach Hazards Statement remains in
effect from midnight through 4pm Friday. A cold front will move
across the lake late this afternoon and west winds behind it will
bring in cooler air and increase to 20-25 knots. Waves in the 3-5
foot range are expected, highest between Grand Haven and South
Haven where they`ll be closer to 4-5 feet.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement through Friday afternoon for MIZ037-043-
     050-056-064-071.
MARINE...Small Craft Advisory until 4 PM EDT Friday for LMZ844>849.

&&

$$

DISCUSSION...04/Thielke
AVIATION...Hoving
MARINE...04