282
FXUS63 KGRR 210629
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
229 AM EDT Mon Sep 21 2026
.KEY MESSAGES...
- Non-zero chance of rain for southern areas into Tuesday
- High confidence of dry and seasonable weather mid-week and beyond
&&
.DISCUSSION...
Issued at 229 AM EDT Mon Sep 21 2026
- Non-zero chance of rain for southern areas into Tuesday
The frontal system that brought the soaking rain to much of the
forecast area over this past weekend, has sank well south of the
area. This has taken all of its rain with it, leaving our area dry.
We are still seeing quite a bit of cloud cover over the area with
the long wave upper trough/low still to our west. These clouds are
mainly high clouds north of the I-94 corridor, with mid level clouds
along and south of I-94.
The upper low is expected to slowly rotate/dig to the SE through
Tuesday. For the most part, it will keep just about all of any
weather with it to the south. The exception to this is the far
southern row of counties where the mid level moisture is, and a
little closer to any short waves with the parent wave. The dry low
level feed of air from the NE will mitigate the chances a bit. Can`t
rule out a little stronger shower being able to produce some light
rain fall that would survive the dry air to the ground during peak
heating today and Tuesday.
- High confidence of dry and seasonable weather mid-week and beyond
There has been good run to run consistency and agreement amongst the
models and ensemble members that we will be entering quite a dry
period from Wednesday through at least next weekend.
The upper low is shown by most data to rotate toward the Mid-
Atlantic area, while additional energy comes onshore over the
Pacific NW. What this means for Michigan is that we will be under
the influence of strengthening upper ridging as the upper air
pattern amplifies between the two upper lows near the two U.S.
coasts. This amplified pattern slows the progression of the systems,
so we are looking at an extended period of the upper ridge directly
controlling our weather.
We will remain a tad cool on Wednesday as the cold pool aloft is
slow to move out. We will then see slow and gradual moderation of
the air mass due to building heights and weak warm air advection as
the cold pool exits completely. Highs should gradually warm into the
70s toward the end of the week and next weekend, with cool and
comfortable overnight temps in the 40s and 50s with a dry air mass
in place.
&&
.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 139 AM EDT Mon Sep 21 2026
A much less impactful forecast for aviation interests as compared
to the last couple of days. VFR is expected to dominate, except
for some isolated MVFR ceilings early this morning.
The lower clouds have just about all pushed south of our terminals
as of early this morning. KGRR had some isolated 2500 ft ceilings,
but that has since cleared out. The I-94 terminals still have a
6-9k ft agl ceiling, which will likely remain through most of
today. Areas north will likely just have the high 20k ft deck,
with maybe some isolated cumulus developing mid-late morning.
Winds will become a bit gusty with diurnal heating today from the
NE. Gusts up to 25 knots will once again be possible, especially
at the northern sites where the heating will be a little better
with less layers of clouds. The diurnal cloud cover and gusty
winds will diminish toward sunset tonight.
&&
.MARINE...
Issued at 229 AM EDT Mon Sep 21 2026
All headlines are down for our nearshore waters, and it is likely we
will not need any for most of the upcoming week.
Winds will be steady for at least a couple of days early this week.
There is a decent pressure gradient between the strong high to our
north, and the low to our south. The offshore component of the wind
will focus the stronger winds over the open waters. We should end up
just short of the wind criteria. The waves will be on the low side
due to the short fetch of the offshore flow.
Winds will relax a bit later this week as the stronger gradient
shifts out of the area.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...NJJ
AVIATION...NJJ
MARINE...NJJ
NWS GRR Office Area Forecast Discussion
