380
FXUS63 KGRR 262256
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
656 PM EDT Thu Jun 26 2025

.KEY MESSAGES...

- Highest Chances for Rain will be Friday and Monday

&&

.DISCUSSION...
Issued at 217 PM EDT Thu Jun 26 2025

Diurnally-enhanced convection along a warm front will persist
into this evening then should diminish overnight. More storms will
fire up on Friday in the warm sector and ahead/along a cold front
as a sfc low tracks across northern Lower Michigan. The front
clears southeast zones late Friday night with a brief period of
fair weather and lower dew points into Sunday morning.

By Sunday afternoon, return flow is already setting up as a
shortwave trough embedded in zonal flow moves from the Plains
into the Great Lakes. Dew points surge back into the 70s by Monday
with a cold front arriving by afternoon. Instability is
sufficient for enhanced thunderstorm coverage but deep layer
shear is only around 20 to 25 knots, so storms may be more of the
pulse variety.

Dew points behind the front fall into the 50s to lower 60s for
Tuesday through Thursday offering a break from the recent
oppressive humidity. Long range indications are for the
possibility of some storminess on the 4th, but confidence is low
in the details.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 652 PM EDT Thu Jun 26 2025

Radar shows showers and thunderstorms continuing to weaken and
dissipate across the region this evening. It`s looking more likely
that the convection west of the lake will dissipate prior to
crossing the lake around midnight and won`t be a factor in the
TAFs.

Showers/storms will likely develop again Friday afternoon and will
mostly affect BTL/LAN/JXN after 19z. VFR expected through the
period.

&&

.MARINE...
Issued at 139 PM EDT Thu Jun 26 2025

Waves will build to around 2 feet north of Holland Friday
afternoon. Otherwise waves will generally be less than 2 feet for
the next couple of days.

Thunderstorms remain a possibility this afternoon and again Friday
afternoon.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Ostuno/RAH/Thomas
AVIATION...04
MARINE...RAH