300
FXUS63 KGRR 301743
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
143 PM EDT Sat Aug 30 2025

.KEY MESSAGES...

- Next Chance for Rain late Wednesday

&&

.DISCUSSION...
Issued at 327 AM EDT Sat Aug 30 2025

- Next Chance for Rain late Wednesday

Surface high dominates the Great Lakes through the first half of
next week with upper height rises bringing slowly moderating
temperatures. The warming will be brief however as another upper
low dives southeast from Canada and carves 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 the end of the week with shortwave troughs and
vorticity maxima rotating around the upper low in broad cyclonic
flow regime along with steep mid level lapse rates.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 142 PM EDT Sat Aug 30 2025

VFR will dominate for most TAF sites over the TAF period. The sole
exception will be JXN. With high pressure and light winds
dominating the pattern, low level moisture at JXN could allow for
another round of shallow fog overnight into Sunday morning. While
it shouldn`t be as extensive, there remains the potential between
06Z to 12Z of reducing vsbys. Have put in a period of IFR vsbys
from 09Z to 11Z accordingly.


&&

.MARINE...
Issued at 142 PM EDT Sat Aug 30 2025

Relatively calm conditions expected for the nearshore waters
through early next week as high pressure dominates the Great Lakes
region. Water and air temperatures will remain rather cool for
swimming. Warmest lake temps remain around Holland State Park.

&&

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

&&

$$

DISCUSSION...Ostuno
AVIATION...Ceru
MARINE...Ceru/Ostuno