990
FXUS63 KGRR 100451
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
1251 AM EDT Sat Oct 10 2026
.KEY MESSAGES...
- Shower chances tonight with warm and breezy weather Saturday
- Very little rain expected for the area with the remnants of Isaias
- Unsettled weather likely Tue and beyond with a strong storm system
&&
.DISCUSSION...
Issued at 200 PM EDT Fri Oct 9 2026
- Shower chances tonight with warm and breezy weather Saturday
We continue to expect a short window for any one location of the
threat of a shower or two from mid-evening into the overnight hours
tonight. Regional satellite and radar imagery shows the active
frontal zone to our SW this afternoon near the Mississippi River
Valley near the MN/IA/WI border.
There is lightning currently associated with the rain out there, but
we remain confident that the threat of lightning here will be
isolated at most, and not even enough to mention at this time. Model
progs show the sfc based and elevated instability expected to
diminish toward evening, and ride almost due north, staying west of
our area. We may see a 200 J/kg of MU CAPE and LI`s both sfc based
and aloft staying above 0c.
Some of the rain is likely to make it to the ground, but that will
be mainly under the heavier showers with moisture quite limited
below 6k ft. All of this should move out of the area prior to
daybreak on Saturday as the warm front passes by, and the nose of
the low level jet moves out.
This will set the entire area up for a warm October day with plenty
of sunshine and breezy conditions.
- Very little rain expected for the area with the remnants of Isaias
Clouds on the leading edge of what is left of Isaias will stream in
Saturday night from the SSE. By 12z Sunday, some rain will lift up
into the area, mainly SE of Grand Rapids. The SE trend has continued
even a little bit more over the last 24 hours, due to the logjam of
systems to the NW. What rain there will be will be light on amounts,
with most of the area that sees rain staying under a tenth of an
inch. Of course some locally higher amounts will be possible.
The clouds and rain will move out by Monday, as the upper trough out
west, and upper ridge immediately west of our area pushes over the
area. Monday is shaping up to be another warm day like Saturday with
a good warm flow from the SW moving in ahead of the next front.
- Unsettled weather likely Tue and beyond with a strong storm system
Monday may be the last nice fall day for a few days, as we are
expected to become under the influence of a much more active and
unsettled pattern for Tuesday and beyond.
The large long wave trough out west will be trying to push east once
Isaias moves out of the way this weekend. Strong ridging over the
southern states will hold back the southern part of the ridge, while
energy flattens out the top of the ridge a bit. This will allow a
cold front to sink south over the area on Tuesday. Moisture is
initially a bit limited as the front moves through. The front stalls
out, and additional short waves are expected to ride along this.
These waves will help produce showers and storms with surges of low
level moisture riding over the front ahead of the waves.
The long wave trough/low that closes off over the SW U.S. is
forecast to lift out into the Plains by Thursday. Strong large scale
forcing ahead of this trough will help to develop a stronger fall
system and lift northward west of our area. If this holds, we would
see a strong surge of warm air around Thursday, with lots of Gulf
moisture that would bring plenty showers and storms to the area. One
can not rule out a severe weather event next Thu if things don`t
change much with the low going negatively tilted over time.
The front would then go through around the Friday time frame, and
bring in much colder air with stronger winds. The northern branch of
the upper jet would sink south of our area, and bring a potential
for lake effect rain showers.
&&
.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1248 AM EDT Sat Oct 10 2026
Overall VFR conditions will dominate the pattern through the TAF
period. There are a few caveats. First, light showers will
continue through southern lower Michigan overnight. The showers
are fairly scattered. The sites expected to have some light rain
are LAN, BTL and JXN. Not expecting any restrictions and
thunderstorms remain unlikely. Showers should end around 08 to
10Z. 25 to 35 knots of LLWS below 1,000 feet is expected over
much of West Michigan between 08 and 15Z.
Winds will mix out with gusts out of the south upwards of 20 kts
after 15Z. Winds should decouple this evening between 00Z to 02Z
Sunday. Another round of Low level wind shear of 25 to 35 knots
will be possible between 02Z to 06Z Sunday.
&&
.MARINE...
Issued at 200 PM EDT Fri Oct 9 2026
As expected, we will be hoisting a Small Craft Advisory for the
increase in wind tonight into Saturday night. The advisory will be
in effect from Holland and to the north where the best wind will be.
This is mostly a warm air advection wind, so the full effects will
not be realized at the surface. The gradient will then weaken
Saturday night as Isaias approaches the area before turning away.
The next headline event looks to begin on Monday. This will be
increasing gradient ahead of the next incoming cold front coming in
from the NW. Much of next week looks windy, especially later in the
week when a stronger system is likely to move over the area.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 5 AM EDT Sunday for LMZ846>849.
&&
$$
DISCUSSION...NJJ
AVIATION...Ceru
MARINE...NJJ
NWS GRR Office Area Forecast Discussion
