202
FXUS63 KGRR 071801
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
200 PM EDT Wed Oct 7 2026
.KEY MESSAGES...
- Mostly dry through much of Friday
- Rain possible on Sunday with the tropical system
- Turning much colder next week with a strong front late Monday
&&
.DISCUSSION...
Issued at 200 PM EDT Wed Oct 7 2026
- Mostly dry through much of Friday
We remain in the same pattern for another 24-36 hours as we have
seen much of this week thus far. That pattern is one where the
northern branch of the upper jet is centered north of the area with
a flow from the WNW. The upper jet is just close enough that we are
seeing additional cloud cover with weak short waves passing by to
our north. A lack of cloud cover and deep instability is keeping us
mainly dry, except for a few sprinkles.
The latest set of model guidance is keeping most of any sprinkles
just north of the forecast area border through much of the day on
Friday. We see a change with the upper air pattern at that time with
upper flow taking on a more WSW flow with the ridge lifting up
toward us. As this occurs, a sfc warm front will be moving through
Friday evening, and will increase the chance of rain some for much
of the area. This is still a low chance, as moisture below 8k ft is
still quite limited.
This will set the stage for a warm October day with widespread 70s,
and maybe an 80 degree reading or two across the south away from
Lake Michigan.
- Rain possible on Sunday with the tropical system
We have been watching the evolution of forecasts with the Tropical
system Isaias over the past few days going from missing the area
completely to the SE, to now possibly bringing some rain in across
southern Lower Michigan on Sunday.
This has been complicated as there is a non-tropical upper low over
SE Texas, and a long wave trough coming in from the West Coast.
Initially, Isaias was being pushed to the NE quickly with the long
wave trough. Now the upper low over TX absorbs Isaias and rotates
almost due north before the upper wave comes in and sweeps it out.
As has been mentioned the past few days, rotating upper low tracks
are difficult to forecast. The trend has definitely been for a
better chance for rain, as the system goes extra-tropical and looks
more like a mid-latitdue system.
- Turning much colder next week with a strong front late Monday
However the system moves in Sunday, and any rain that falls will be
on its way out by late Sunday. We will see a narrow upper ridge
build in briefly between the extra-tropical system, and the larger
trough coming in from the NW. This trough will have reinforcement
coming in from the NW. The front will move in Monday evening, and
pass through Tuesday. The strong forcing ahead of this trough will
bring a bout of rain to the area.
Behind the system on Tuesday and beyond, we will see a fairly decent
Canadian high set up and bring some much cooler air in over the
area. Highs are likely to be only in the 50s, and some lake effect
rain will be possible.
&&
.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 106 PM EDT Wed Oct 7 2026
A weak cold front is moving across the Lower Peninsula early this
afternoon. Virtually no clouds accompany the front, just a minor
wind shift. Clear skies are expected through the period.
&&
.MARINE...
Issued at 200 PM EDT Wed Oct 7 2026
We are cancelling the Small Craft Advisory that has been in effect
the last couple of days. We will be turning around and issuing the
next Advisory for this evening and Thursday morning. We are in a
brief reprieve between events right now with waves having dropped
below 4 ft. This is associated with a weak ridge moving through this
afternoon.The gradient will tighten up enough in its wake beginning
this evening, to require another advisory be issued. This will last
through Thursday morning before waves come down enough.
We will see another break in the wind and wave action later Thursday
through Friday morning, before winds come up again behind a warm
front that will be moving through the area late Friday. Winds will
hold up then through Saturday night.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory from 8 PM this evening to noon EDT Thursday
for LMZ844>849.
&&
$$
DISCUSSION...NJJ
AVIATION...04
MARINE...NJJ
NWS GRR Office Area Forecast Discussion
