342
FXUS63 KGRR 300638
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
238 AM EDT Wed Sep 30 2026
.KEY MESSAGES...
- Rain through Thursday night
- Cooler weekend, frost/freeze potential
&&
.DISCUSSION...
Issued at 238 AM EDT Wed Sep 30 2026
- Rain through Thursday night
A fairly long duration light rain event is unfolding across Lower
MI. Radar shows light rain from the central UP southwest to New
Mexico along a cold front moving eastward across northern
Wisconsin. This frontal boundary will sag south across the central
cwa today and then remain quasi stationary until Thursday night.
Meanwhile, abundant moisture moving north from the Gulf in
conjunction with subtropical moisture from the Pacific will help
to create light to moderate rainfall during the next 48 hours.
We`ll wait until low pressure over the southern Plains finally
gets kicked out by a northern stream short wave for the frontal
boundary across the cwa to finally move south. That will allow
cooler air to move into the region.
Instability is somewhat anemic with this system and so we are
expecting mostly rain. However, instability increases a bit
tonight and we could see a non severe thunderstorm or two south
of I-96. Total QPF 1-2 inches is possible...highest over the west
central cwa.
Rain will end from north to south early Friday once the cold front
moves south, leading to some sunshine late in the day.
.KEY MESSAGES...
Highs will be in the mid to upper 60s today through Friday.
- Cooler weekend, frost/freeze potential
H8 temperatures fall from 16c to 6c between Thursday afternoon and
Friday afternoon. If skies clear Friday, we could see subfreezing
temperatures along US-10 Friday night and mid 30s south to M-46.
Another cold front moves through Sunday night and sends sends h8
temperatures down to -2c by Monday morning. Lows Monday morning
will be in the lower 30s across the northern cwa, but it`s Tuesday
morning that will be the coldest of the season...so far...with
temperatures in the mid to upper 20s over the northern cwa and
lower to mid 30s elsewhere; frost/freeze headlines will most
likely be needed Monday night. Highs Tuesday will be around
60...almost 10 degrees below normal.
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 238 AM EDT Wed Sep 30 2026
Currently, all of the terminals are VFR, but it`s not going to
last. Radar shows light rain stretching from northern Lower
southwest into the central US and it`s heading toward southwest
Lower. We`ll see light rain develop at MKG first around 09z and
gradually move south with time. Ceilings will also lower too and
become IFR by early afternoon at MKG and during the evening at
GRR. However, the rest of the terminals should only fall to MVFR
during the period.
&&
.MARINE...
Issued at 238 AM EDT Wed Sep 30 2026
Based on latest wave height guidance, we`ve extended the headlines
south to Holland. No change to the duration. Waves will increase
to 3 to 7 feet today north of Holland and then diminish later
tonight.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement through Thursday morning for MIZ037-043-
050-056.
MARINE...Small Craft Advisory until 8 AM EDT Thursday for LMZ846>849.
&&
$$
DISCUSSION...04
AVIATION...04
MARINE...04
NWS GRR Office Area Forecast Discussion
