383
FXUS63 KGRR 201053
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
653 AM EDT Sun Sep 20 2026

.KEY MESSAGES...

- Additional rain mainly far south through today

- Small chance of residual showers south for Monday and Tuesday

- Seasonable and mainly dry Wednesday and beyond

&&

.DISCUSSION...
Issued at 309 AM EDT Sun Sep 20 2026

- Additional rain mainly far south through today

We have cancelled the Flood Watch a few hours early this morning.

We have seen quite a bit longer of a break of the steady and heavier
rain than expected Saturday afternoon through the current time. It
seems that the area of showers/storms that moved through Saturday
morning, pushed the elevated baroclinic zone/front aloft a bit
further south. The low level jet has taken time to re-establish
itself, which it is now doing to our SW.

It is likely that the band of rain completely SSW of the forecast
area early this morning could sneak up to our far SW corner as the
next wave pushes it north just a little bit. Consensus from new
model guidance and mean amounts show that far SW Van Buren could see
an inch or so of rain today, with lesser amounts to the NE. This
area did not see the heavier amounts yesterday, as they were a
little further north. The bottom line is we are not expecting any
areas to see 4-5 inches total from this that was the impetus for the
Watch.

It may take much of the day for the rain to push south of the area
once it moves in, but all areas should be dry by sunset tonight.

- Small chance of residual showers south for Monday and Tuesday

The boundary that has been the focus of the rain the last few days
is expected to be pushed further south, and will be much less of an
influence on the area as compared to the last couple of days.

The upper low that is in charge of the synoptic pattern over the
region is showing signs over having less of an influence on the
weather for Southern Lower, resulting in lower chances of rain for
only the southern areas through Tuesday. This trend is the result of
the upper low complex showing more likelihood that it rotates
further south, and has much less of a direct influence on our
weather as a stronger high pushes it south away from the area.

- Seasonable and mainly dry Wednesday and beyond

The models are in good agreement (for now) that the upper low will
move far enough away by Thursday that we get under the influence of a
stronger long wave ridge that slowly builds toward the area. This
will get held up by stronger systems to our west and east. We will
start out cool with highs barely in the 60s. Building heights and a
flow of warmer temperatures eventually from the south will push max
temps back up in the 70s for the latter half of the area with lows
in the 40s and 50s.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 653 AM EDT Sun Sep 20 2026

We continue to see the LIFR -VLIFR conditions in place for mainly
ceilings, but some visibilities also. Rain shield has now moved in
over most of the terminals, except KMKG. This rain will hold for a
few hours at KGRR and KLAN, and the I-94 for most of the day. The
low level flow from the NE will try to improve the ceilings slowly
as drier air moves in and there is some diurnal lifting. The
northern terminals will see this sooner than the southern
terminals.

We do expect to see most, if not all sites slowly become VFR by
mid evening. Clouds may clear for the I-96 terminals tonight,
while the clouds hold for the I-94 corridor.

&&

.MARINE...
Issued at 309 AM EDT Sun Sep 20 2026

We will be issuing a Small Craft Advisory for the northern two
marine zones for today and tonight. We will be holding off on a
Beach Hazards statements due to more of an offshore flow and the
weather preventing it from being a good beach day this late in the
season.

Strongest winds behind the departing system will be across northern
areas beginning later this morning, and then waves coming down
overnight. The southern areas will see winds near criteria, but it
is marginal considering they will be completely blowing offshore.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory from 11 AM this morning to 2 AM EDT Monday
     for LMZ848-849.

&&

$$

DISCUSSION...NJJ
AVIATION...NJJ
MARINE...NJJ