510
FXUS63 KGRR 040534
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
134 AM EDT Wed Jun 4 2025

.KEY MESSAGES...

- Shower and thunderstorm chances increase tonight into Wednesday

- Mostly dry with seasonable temperatures late week

- Unsettled weather returns by early next week

&&

.DISCUSSION...
Issued at 310 PM EDT Tue Jun 3 2025

- Shower and thunderstorm chances increase tonight into Wednesday

Today`s breezy/warm conditions will extend into this evening, as
southerly winds continue to bring mid 60s dew points into the
area. A nice taste of early summer. Meanwhile, to the west, a cold
front extending from the central U.P. to eastern Iowa will slowly
move our way, ultimately bringing an increase in rain chances.
Showers/storms are currently blossoming and moving quickly to the
NE across WI, where MLCAPEs are between 500-1000 J/kg and PWATs
exceed 1.5 in. The front, instability, and moisture axis will inch
our way tonight. Scattered showers and non-severe storms may
impact areas N/W of a GRR-MOP line this evening, then a weakening
band of showers will come into the region well after midnight
/toward daybreak/. Lows will be mainly in the 60s... coolest over
the far N and W.

The cold front and it`s associated showers will move
slowly/steadily across the area Wednesday. Daytime warming and
frontal timing will dictate extent of renewed thunderstorm
development. At this time, expect an uptick in storms SE of a
AZO/MBS line after 16-17Z. Models show MLCAPES below 1k J/kg and
modestly strong deep unidirectional flow aloft /featuring 500 mb
winds of 50-55 kt/. This setup suggests the possibility of
marginally severe wind gusts with any storms that develop in the
afternoon - again, SE of AZO/MBS line. By the time the
showers/storms diminish Wednesday night, most areas should
receive between a quarter and a half inch of rainfall /locally
higher in Wednesday afternoon storms/.

- Mostly dry with seasonable temperatures late week

The aforementioned front will be east of MI by early Thursday, and
weak surface high pressure will attempt to build into the Great
Lakes Thursday/Friday, as upper flow becomes quasi-zonal. Ensembles
/particularly the GEFS/ hint that a weak upper wave embedded in the
zonal flow will pass south of the area Friday and perhaps support
showers. Overall, however, expect mainly dry weather Thursday
through at least Saturday, with high temperatures close to seasonal
norms in the 70s.

- Unsettled weather returns by early next week

Ensemble guidance agrees that a SEWD moving upper wave will amplify
over the upper Great Lakes region by late Sunday and Monday. The
Euro ensemble is the most robust, and the ensemble mean shows a
closed 552 dm 500 mb low over Lake Superior by Monday morning.
Forcing from the upper wave, cooler air aloft, coupled with the
June sun angle, should support diurnally enhanced showers and
storms late Sunday into Monday. Daytime highs should remain mostly
in the 70s.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 134 AM EDT Wed Jun 4 2025

A front will slowly shift east through the area overnight and
through Wednesday. Ahead of this front scattered rain showers are
expected with gradually lowering ceilings to IFR and MVFR values.
Southwest winds gusting 20 to 25 knots are also expected to
continue ahead of the front. Thunderstorms will be possible later
Wednesday morning into the afternoon with the best chances toward
LAN and JXN. Some stronger storms are possible with strong winds
and hail. Lighter northwest winds move in behind the front with
gradually lifting ceilings.

&&

.MARINE...
Issued at 310 PM EDT Tue Jun 3 2025

Gusts will increase to near 30 knots over the next few hours
continuing into early Wednesday morning. These southwest winds will
also build waves into the 4-7 foot range north of Holland and 2-4
foot south of Holland. As a result, a Small Craft Advisory is in
effect for Lake Michigan between St. Joseph and Manistee. A Beach
Hazards Statement remains in effect for areas north of Holland for
dangerous waves and currents, while a moderate swim risk is expected
south of Holland. Winds and waves subside Wednesday morning with
northerly winds through Saturday at or below 15 knots.

Showers and thunderstorms are expected tonight into Wednesday. Brief
gusts in excess of 34 knots in any stronger storms that develop
tonight, mainly north of Grand Haven. Waves will also be locally
higher near the stronger storms.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 8 AM EDT this morning for MIZ037-
     043-050-056.
MARINE...Small Craft Advisory until 8 AM EDT this morning for LMZ844>849.

&&

$$

DISCUSSION...Smith
AVIATION...RAH
MARINE...Thomas