225
FXUS63 KGRR 010549
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
149 AM EDT Thu Oct 1 2026

.KEY MESSAGES...

- Rain into early Friday

- Clear and cold with possible frost/freeze

&&

.DISCUSSION...
Issued at 250 PM EDT Wed Sep 30 2026

- Rain into early Friday

Tropical moisture has begun to stream through the region today.
A large upper level low is moving through the four corners region
of southwest USA and propagating eastward. That low is advecting
copious amounts of Gulf moisture along a boundary between a large
upper level low moving across northern Canada and a high pressure
system residing over southeastern US. That strong gradient is
bookmarked by a trough situated over the Mid Atlantic. This
formation is allowing that ribbon of gulf moisture to stream
through the midwest and Great Lakes region through tomorrow night.

Upwards of three to four tenths has fallen across the
Lower peninsula with periods of light to moderate rain
continuing. The period with the most moisture should be through
the first half of tomorrow. NAEFS and EC ensembles are showing
average PWATS upwards of 1.75 inches streaming across southern
Lower Michigan. This could correlate to additional 1 to 2 inches.
Locally higher amounts along lakeshore upwards of 2 to 2.5 inches
are possible. However given the dry soils, flooding is not a
concern at this time. The areas to could see showers overperform
are Muskegon, Oceana and Newaygo counties.

- Clear and cold with possible frost/freeze

The before mentioned upper level system through Canada will engulf
the low that is moving through the southwest. That will create a
trough that will stretch across most of the US and drive the high
pressure eastward. This will shift the moisture through the Mid
Atlantic and through the southern US Friday. This will bring
cooler, drier air through Michigan. Expect Autumn temperatures
through the latter half of the week and through the weekend. Below
normal minimum temperatures are expected this weekend. Overnight
lows could reach frost/freeze north of I 96, especially along the
US 10 corridor.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 145 AM EDT Thu Oct 1 2026

I-96 is the rough delineation between VFR conditions to the south
and IFR to the north. This is where the front aloft is located.
This boundary may wiggle back and forth a bit through early
afternoon before sinking south and dragging IFR cigs with it.
Thus, we have IFR conditions at all of the terminals at some
point this afternoon, continuing through the remainder of the
period.

&&

.MARINE...
Issued at 255 PM EDT Wed Sep 30 2026
 The strong gradient will keep winds and waves of SCA criteria
going north of Holland through the rest of the day and into early
Thursday morning. Waves will slowly subside overnight but waves
north of Grand Haven overnight of 3 to 7 feet are likely.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 8 AM EDT this morning for MIZ037-
     043-050-056.
MARINE...Small Craft Advisory until 8 AM EDT this morning for LMZ846>849.

&&

$$

DISCUSSION...Ceru
AVIATION...04
MARINE...04