928
FXUS63 KGRR 041837
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
237 PM EDT Thu Sep 4 2025

.KEY MESSAGES...

- Strong Winds late tonight through Friday Morning

- Cool with another chance for rain Saturday


&&

.DISCUSSION...
Issued at 230 PM EDT Thu Sep 4 2025


- Strong Winds late tonight through Friday Morning

 The fast moving upper level low will move through the upper
midwest and through northern Michigan tonight through Friday
morning. The biggest concern remains the potential for 40 mph or
more winds. There will be a strong core of wind aloft. The
question is whether that weather will mix to the surface. The HREF
mean 925 mb (approx 1500 feet) southwesterly winds peak around
40-45 knots over our area between 5 AM and 10 AM. There remains
the potential for gusty winds but the variability in stability
will mean we will hold off on any headlines for now.  While there
will be some rainfall associated with this system it will be
around a quarter of an inch.

- Cool with another chance for rain Saturday

 Cooler air will filter in behind this front with another front
moving through Saturday. That will allow for lows into the 40s.
That weak system will move through late Saturday into Sunday,
bringing another chance for showers with gusty winds, albeit
weaker than Friday`s, possible Saturday afternoon

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 144 PM EDT Thu Sep 4 2025

The first 6-10 hours of the TAF period will be relatively quiet
before low pressure moves into the Great Lakes Region. This low
will bring wind shear, scattered showers and gusty southwest winds
to lower Michigan. Showers should mostly be focused on a 6 hour
or so window 06z-12z. Wind shear should be around for most of that
06z-12z period as well and may linger through the end of the TAF
period even as surface winds mix out and gust over 25kts.

&&

.MARINE...
Issued at 356 AM EDT Thu Sep 4 2025

Slight chance of a waterspout this morning as a few lake-effect
showers linger along a wind convergence zone between Muskegon and St
Joseph, but the low convective depths are keeping that threat
marginal.

West winds during the day will be comparatively relaxed, though
waves will remain marginally hazardous for small craft and swimmers.
Southwest winds increase substantially tonight, becoming gales to 40
knots after 2 AM until late Friday morning. The winds are expected
to peak around daybreak. Hazardous winds and waves for small craft
and swimmers then continue Friday afternoon into Saturday.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement through Saturday morning for MIZ037-043-
     050-056-064-071.
MARINE...Small Craft Advisory until 2 AM EDT Friday for LMZ844>849.
     Gale Warning from 2 AM to 11 AM EDT Friday for LMZ844>849.

&&

$$

DISCUSSION...Ceru
AVIATION...Maczko
MARINE...CAS