979
FXUS63 KGRR 252237
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
637 PM EDT Fri Sep 25 2026

.KEY MESSAGES...

- Dry through Tuesday, then unsettled

&&

.DISCUSSION...
Issued at 142 PM EDT Fri Sep 25 2026

- Dry through Tuesday, then unsettled

Latest visible loop shows quite a bit of cloudiness moving across
Lower MI in conjunction with a short wave aloft. Once the wave
moves east this evening, clearing will occur from the west.

The large ridge in place over the Great Lakes will get squeezed a
bit from the large low over the mid Atlantic but won`t have much
influence over the cwa this weekend. Instead, we`ll see quite a
bit of sunshine that will carry over into mid week. Highs will
warm to the lower to mid 70s by Tuesday before retreating into the
60s midweek.

The ridge will break down by Tuesday as a northern stream wave
moves across Canada and pushes a cold front across Lower MI.
Concurrently, a southern stream wave will move east from
California across the Southern Rockies. At that point, the
remnants of Polo will be arriving in New Mexico and get entrained
into the southern low. The end result is that that moisture will
then ride northeast along the frontal boundary and toward the cwa.
The GFS is a bit quicker moving the cold front through compared to
the ECMWF, but both models bring rain back into the region as the
southern low moves north. Thus, the latter half of next week looks
unsettled with periods of showers and isolated thunder.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 637 PM EDT Fri Sep 25 2026

Primary source of forecast uncertainty with this package is the
potential for fog and/or low stratus development overnight thanks
to light northeast flow off of Lake Huron/Saginaw Bay. Have
trended JXN down to sub fuel-alternate MVFR based on a consensus
of short range model guidance and the favorable setup however
there is a 30% chance of IFR cigs based on the latest
probabilistic guidance dependent on the extent of clearing and
decoupling. LAN is not confident enough to add restrictions yet
but would be next likely to see them (30% chance MVFR) all other
terminals are favored to remain VFR overnight at this time. Expect
winds aob 10 knots through the period with a westerly lake breeze
developing at MKG Saturday afternoon.

&&

.MARINE...
Issued at 142 PM EDT Fri Sep 25 2026

Wind and waves will remain below advisory criteria through the
weekend. High pressure to the northeast will generate offshore
winds through Monday. Highest waves will be 1-2 feet near the 5
mile mark off shore. The high will move east Tuesday and south
winds will increase, at which point a headline may be needed.

&&

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

&&

$$

DISCUSSION...04
AVIATION...Thomas
MARINE...04