234
FXUS63 KGRR 262307
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
707 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 /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 707 PM EDT Sat Sep 26 2026
VFR expected with light winds between N and NE for this evening.
Sunday morning, especially between 09 and 13 Z, will be the next
possibility for fog. Similar to Saturday morning, when LAN had
vicinity fog and there was some river valley fog just northeast
of GRR, areas of fog may develop, perhaps becoming locally dense
to 1/2SM or less.
Moisture below 500 feet is expected to flow from Lake Huron this
evening toward LAN and may approach GRR, BTL, and JXN by early
morning. Initially 10-15 knot winds a few hundred feet above
ground for the first part of tonight may weaken prior to sunrise
and allow fog to develop. 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 and BTL, and a 30 percent
chance at AZO.
&&
.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
NWS GRR Office Area Forecast Discussion
