441
FXUS63 KGRR 301024
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
624 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 /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 618 AM EDT Wed Sep 30 2026
Radar shows a large area of light rain slowly moving across the
region and currently falling at MKG. GRR will see light rain begin
within the next hour.
A cold front will slowly move south across the Lower Peninsula and
stall over southern Lower later this afternoon before lifting
north tonight as low pressure approaches from the southwest. IFR
cigs will be noted north of the boundary. Once the front lifts
north, the southern terminals will likely lift back up to VFR
after midnight.
&&
.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
