463
FXUS63 KGRR 221708
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
108 PM EDT Tue Sep 22 2026
.KEY MESSAGES...
- Slight chance of a rain shower South on Wednesday
- Dry weather with slowly warming temperatures into next week
&&
.DISCUSSION...
Issued at 245 AM EDT Tue Sep 22 2026
- Slight chance of a rain shower South on Wednesday
We continue to see the upper low over Eastern Iowa as of this
morning, continue to weaken and lose its moisture and associated
precipitation. The frontal system that was the focus of the heavy
rain over the region this past weekend, has now completely
separated, and the dry low level flow from the NE eat away at much
of the rain.
Today looks to be a dry day, while the best small chance of rain
looks to be over the south on Wednesday afternoon.
We look to have some diurnal cumulus development again today, but
not as extensive as yesterday. This is likely due to the upper level
temps moderating, and resulting instability weaker. We continue to
have fairly dry conditions below 15k ft, minus the cumulus clouds.
Forecast soundings show this well. There will not be much vertical
development with a fairly strong inversion around 4-5k ft,
especially with low boundary layer dew points.
This changes a bit later tonight and Wednesday for southern areas.
Most model guidance indicates that some low level moisture will
rotate around the low to our south and up and over the southern
portion of the forecast area. This added moisture in conjunction
with weak short waves in the vicinity will be just enough for a few
light showers.
- Dry weather with slowly warming temperatures into next week
The amplification of the upper air pattern is still expected to
take shape with the low expanding over the Eastern Seaboard, and the
upper ridge building to our west over the upper Plains. It might be
taking a little longer for everything to fall in place than
previously thought, which is fairly common with upper lows. It still
looks like we will see the upper ridging build over the area, and
hold in place through early next week. We will be under the
confluent flow downstream of the ridge, providing plenty of
subsidence for the area.
Temperatures again will remain cool through Wednesday with the upper
low and cold pool aloft nearby. Temperatures will moderate then as
warmer air builds in and we see much more sunshine.
&&
.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 108 PM EDT Tue Sep 22 2026
Expecting mostly VFR this afternoon with cloud layers around
3,500 feet and 20,000 feet, and northeast winds gusting up to 20
or 25 knots. Can`t rule out some temporary 3,000 ft ceilings at
JXN this afternoon. Tonight, cloud cover should increase
especially around AZO, BTL, and JXN, and conditions could slip
into MVFR at times with clouds between 3,000 and 4,000 feet.
Also expect about 20 knots of LLWS between 1,000 feet and ground
between 01 and 12 Z, with winds at 1,000 feet about 08030KT.
&&
.MARINE...
Issued at 245 AM EDT Tue Sep 22 2026
We continue to see the brisk offshore winds over the nearshore
waters this morning, and continue through Thursday, before winds
settle down a bit. The setup responsible for this continues to be
the relatively strong gradient between the sfc high to our north,
and the low to our south. The offshore component keeps the winds
just below criteria.
We will see much lighter winds by Friday, and continue through the
weekend.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...NJJ
AVIATION...CAS
MARINE...NJJ
NWS GRR Office Area Forecast Discussion
