456
FXUS63 KGRR 041935
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
335 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 335 PM EDT Thu Sep 4 2025

Dangerous winds and waves this afternoon and evening will increase
in intensity early Friday. Gales of 40kts or higher are expected
for all marine zones overnight tonight with waves of more than 10
feet expected at times. Some improvement in conditions late
Friday but hazardous winds and waves to small craft and swimmers
should persist 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...Maczko