945
FXUS63 KGRR 311129
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
729 AM EDT Sun Aug 31 2025

.KEY MESSAGES...

- Next Chance for Rain late Wednesday

&&

.DISCUSSION...
Issued at 243 AM EDT Sun Aug 31 2025

- Next Chance for Rain late Wednesday

Overall pattern remains highly amplified and a bit blocky over the
next week, more typical of autumn than late summer. We start off
with a cool surface high moving east with moderating temperatures
as upper ridging builds across the northern Great Lakes through
the first half of the week. This is followed by an upper low
diving southeast from Canada and carving out a longwave trough
across the central and eastern CONUS by late in the week. Moisture
streaming up from the south will converge with the trough axis
and a surface low trailing a cold front by Wednesday night with
showers and a few thunderstorms possible.

Diurnally driven showers with some lake enhancement are possible
on Thursday through next weekend with shortwave troughs and
vorticity maxima rotating around the upper low in broad cyclonic
flow regime along with steep mid level lapse rates. Unusually cold
airmass for early September builds in by the end of next week with
temperatures again well below normal. Some scattered frost is
possible again in the northern interior zones if skies clear and
winds decouple from Thursday night into next weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 728 AM EDT Sun Aug 31 2025

VFR conditions will continue through Sunday night. Winds will be
light and variable.

&&

.MARINE...
Issued at 118 AM EDT Sun Aug 31 2025

High pressure will bring light winds and waves a foot or less
through mid-week. A Small Craft Advisory may be needed by
Wednesday and Thursday as low pressure moves through.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Ostuno
AVIATION...Ostuno
MARINE...Ostuno