333
FXUS63 KGRR 261825
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
225 PM EDT Sat Sep 26 2026

.KEY MESSAGES...

- Beautiful Fall Conditions through Tuesday

- Rain Chances Return Tuesday Night and Continue through Week

&&

.DISCUSSION...
Issued at 225 PM EDT Sat Sep 26 2026

- Beautiful Fall Conditions through Tuesday

High pressure remains in place with troughing to our east and
west. Mostly sunny conditions are expected through Tuesday with
highs in the upper 60s along the lakeshore to mid 70s further
inland. Lows overnight will mainly be in the 40s with a few spots
potentially dropping into the upper 30s tonight toward US-10.

- Rain Chances Return Tuesday Night and Continue through Week

Cluster analysis and long range ensembles all point to high
pressure weakening over the area midweek with a trough moving
through late Tuesday night into Wednesday. Instability is low
therefore not expecting thunderstorms at this time. Moisture
increases with precipitable water values around the 90th
percentile (1.6 inches) shown in the mean of each cluster in the
cluster analysis. There are some isolated members that approach 2
inches (record precipitable water levels) as mentioned in the
previous discussion, however those probabilities are low.

Additional shortwaves move through the area for the remainder of
next week. There are some differences in the extended with the
timing of each of these shortwaves, but ensembles show agreement
that most will see some rain accumulations each day. WPC
highlights rainfall amounts in the 1-2 inch range Tuesday through
Saturday. Some isolated higher amounts are possible (20 percent)
as highlighted by individual ensemble members.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 156 PM EDT Sat Sep 26 2026

VFR is expected the rest of the day with light winds mostly from
the northeast (with some directional variability likely). Sunday
morning, especially between 09 and 13 Z, will be the next
possibility for patchy or shallow fog. LAN had vicinity fog this
morning. Some river valley fog just northeast of GRR was also
viewed on satellite when the sun came up. Some things working
against fog include dry air mixing down today, and winds 10-15
knots a few hundred feet above ground tonight. Still, the REFS is
going for about a 70 percent chance of IFR vis at LAN, slightly
higher than what it had for yesterday`s setup. It also has about a
50 percent chance of IFR at JXN, a 40 percent chance at GRR, AZO,
and BTL, and a 10 percent chance at MKG.

&&

.MARINE...
Issued at 225 PM EDT Sat Sep 26 2026

Tranquil conditions continue with low wave heights and light
easterly winds. Winds will become more onshore each afternoon as
the lake breeze develops. Winds turn to the southwest Tuesday then
turn to the northwest Thursday night behind the front. Winds and
waves may approach Small Craft Advisory criteria at times
Wednesday into Friday.

&&

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

&&

$$

DISCUSSION...RAH
AVIATION...CAS
MARINE...RAH