616
FXUS63 KGRR 071939
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
339 PM EDT Mon Jul 7 2025

.KEY MESSAGES...

- Chances for Rain on Wednesday and the Weekend

&&

.DISCUSSION...
Issued at 338 PM EDT Mon Jul 7 2025

- Chances for Rain on Wednesday and the Weekend

A couple shortwaves troughs move through a quasi-zonal flow
regime the next few days bringing the chance for some rain on
Wednesday and again over the weekend.

Severe weather threat is minimal on Wednesday with marginal
instability and deep layer shear of 20 to 25 knots and with the
main batch of showers expected late Tuesday night into Wednesday
morning. Diurnal enhancement of showers is expected Wednesday
afternoon and into early evening. Pulse type storms are possible
with an isolated downburst threat, mostly across the east central
zones where more instability and deeper moisture is forecast to
be.

Shortwave ridging brings mainly dry weather into Friday before the
next trough amplifies across the Northern Plains with ample
moisture return ahead of it. Strong pulse-type storms are
possible by Saturday afternoon with weak/moderate shear profiles
and close to 2000 J/kg CAPE progged by GFS. Showers diminish by
Sunday as drying and subsidence moves in from the west.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 121 PM EDT Mon Jul 7 2025

Skies are clearing from west to east this afternoon with all sites
breaking from MVFR into VFR conditions over the next few hours.
Once a terminal breaks out into VFR, that will continue through
this evening before a moderate (30-40 percent) chance of MVFR fog
develops overnight at AZO, BTL, and JXN. Confidence is too low for
TAF inclusion but will continue to monitor. Scattered clouds at
or above 10kft arrive Tuesday morning with scattered showers
approaching MKG by the end of the TAF window.

&&

.MARINE...
Issued at 338 PM EDT Mon Jul 7 2025

No significant changes to the overall thinking. Increasing winds
along the shoreline will lead to a period of moderate to high swim
risk conditions near and south of Muskegon, particularly for
Ottawa and Muskegon Cos and the adjacent waters. Given observations
currently show at least borderline Beach Hazards/Small Craft
conditions ongoing with the best winds over the next few hours will
keep these hazards as is.

Winds and waves remain below hazardous levels Tuesday. The next
day to watch for potential beach hazards/small craft advisory
level conditions is Wednesday where an approaching high may once
again lead to an increased burst of winds along the lakeshore in
the afternoon. This potential will become clearer in the next day
or so as we move into short range model territory but is already
being hinted at in the NAMNEST and FV3.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 10 PM EDT this evening for MIZ050-
     056-064-071.
MARINE...Small Craft Advisory until 10 PM EDT this evening for LMZ844>847.

&&

$$

DISCUSSION...Ostuno
AVIATION...Thomas
MARINE...Thomas