365
FXUS63 KGRR 080541
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
141 AM EDT Tue Jul 8 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 /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 141 AM EDT Tue Jul 8 2025

We continue to expect VFR conditions will dominate at all of the
terminals for the next 24 hours. As mentioned in the previous
discussion, can not rule out some light fog at KJXN with lighter
winds and the tendency for it to happen at KJXN, but confidence is
not high enough at this time to include.

High clouds are currently in place over all of the terminals.
There are a couple of isolated showers over Eastern Wisconsin, but
we do not expect they will make it this far east. There will be
some higher based cumulus development and blow off from the tops
around 10k ft agl during the core of the daylight hours after mid
morning. The cumulus will then dissipate toward sunset, with some
mid level clouds remaining.

&&

.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...None.
MARINE...None.

&&

$$

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