857
FXUS63 KGRR 141715
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
115 PM EDT Wed Oct 14 2026
.KEY MESSAGES...
- Wet and windy system Thursday through Friday
- Cool and dry weekend with moderating temperatures next week
&&
.DISCUSSION...
Issued at 302 AM EDT Wed Oct 14 2026
- Wet and windy system Thursday through Friday
A few showers will remain possible early this morning before
ending/moving south of the forecast area by daybreak. The vast
majority of the convection is already south of the area closer to
the sfc boundary where the better instability is found. The short
wave that is helping to fuel these showers and storms will be
shifting east of the area by 12z this morning. We are expecting a
considerable amount of cloud cover to hold much of the day as plenty
of low level moisture will advect south from Canada behind the short
wave. Holes in the clouds should develop as the clouds lift with
diurnal mixing helping a bit.
Our attention then turns to the phasing system that has generally
been handled well quite consistently by the models for days now. The
southern stream part of this system will push showers and a few
storms over the area beginning mid to late Thursday. This will be
associated with a sfc low that is forecast to ride through our
forecast area Thursday evening.
Thu evening will be the best chance for better rain and the best
chance of storms. This is when we see the best instability approach
the area via the best moisture push associated with the nose of a 50
knot low level jet clipping the far southern portion of the area.
Instability progs show that we likely do not see sfc based
instability this far north, but we do see sufficient elevated
instability. This setup should keep most, if not all of the severe
potential south.
We may see a brief break in the rain as the southern feature moves
out by Friday morning, and the northern stream trough is still to
our NW. The upper jet core crosses the forecast area Friday
afternoon, bringing the cyclonic flow overhead at that time. This is
delayed a bit compared to earlier runs, and is likely to hold
rain/showers over the area longer on Friday. The showers will be the
result of the deep cold pool aloft with diurnal instability, and
lake effect. The best chance of showers will be Friday afternoon
into Friday evening until the upper jet core on the backside passes
east.
We are looking at a legit chance of lake effect thunderstorms Friday
afternoon and evening. Forecast soundings modified for lake effect
show lifted parcels way above the ice generation layer, allowing for
lightning to be generated. The thunder chance will be limited to
mainly the lakeshore. All of this will be accompanied by winds of 35
to 45 mph bringing in the much colder air.
- Cool and dry weekend with moderating temperatures next week
By Saturday morning, sfc ridging will be over the area already as
the upper trough moves by and we are downstream of the next long
wave ridge. This ridge will become a familiar feature as it is
expected to hold over the area through early next week. It gets held
up with the strongly amplified pattern with strong lows near both
coasts of the CONUS.
We start off quite cool in the wake of Friday`s system for the
weekend. Temperatures may end up in the 50s only once again on
Saturday. We will see a gradual warming trend then through early
next week with dry weather. A better push of warmer air comes around
Tuesday as return flow brings a warm front toward the area. This
could bring a small chance of some rain.
&&
.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 112 PM EDT Wed Oct 14 2026
Satellite and observational trends show MVFR cigs are lifting to
VFR, however intermittent MVFR is likely through late afternoon.
VFR is expected then this evening into the first part of the
night, before clouds increase around 3500 ft tonight, potentially
falling to 2500 ft with boundary layer cooling. Best signal for
MVFR potential is LAN/JXN, with weaker low-level moisture further
west so have gone with SCT 2.5kft cigs at other terminals for
now. At these sites, MVFR is forecast to set in near or shortly
after 18z.
&&
.MARINE...
Issued at 302 AM EDT Wed Oct 14 2026
We will be hoisting a Gale Watch from late Thursday night through
Friday evening. There is good agreement amongst the various model
suites, and there has been good run to run consistency with this
system with regards to winds on the lakes. This also is a solid
Gale event, versus being a borderline event.
We should see winds and waves come down significantly for Friday
night and early Saturday. Winds will come up again later Saturday
and persist at least through the weekend.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Gale Watch from late Thursday night through late Friday night
for LMZ844>849.
&&
$$
DISCUSSION...NJJ
AVIATION...Thomas
MARINE...NJJ
NWS GRR Office Area Forecast Discussion
