textproduct: Grand Rapids

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.