288
FXUS63 KGRR 180812
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
412 AM EDT Sat Apr 18 2026
.KEY MESSAGES...
- Cooler For A Few Days, Then Warming Back Up Mid-Late Week
&&
.DISCUSSION...
Issued at 412 AM EDT Sat Apr 18 2026
- Cooler For A Few Days, Then Warming Back Up Mid-Late Week
Welcome relief from the recent rainy pattern as a progressive
synoptic trough over Canada and the northern CONUS sweeps a cold
front through this morning, with 850 mb temperatures expected to
cool 20 C in 24 hours, between early this morning and early Sunday
morning. A shortwave digging into the backside of the trough over
Michigan on Sunday may support some wet snow showers. The coldest
air, down to -10 C at 850 per the ECMWF, will be in place
underneath a center of high pressure Sunday night. As a result,
lows in the 20s are favored Sunday night / Monday morning. Note,
we will begin the frost/freeze headlines for Muskegon, Kent,
Montcalm, Gratiot, and south. High temperatures Sunday and Monday
are favored to be in the 40s, about 10-15 degrees below normal.
Ensembles do have pretty good agreement on temperatures rebounding
into the 60s Tuesday as the synoptic wave pattern progresses
eastward and southwesterly flow brings warmer air back. Most
ensemble members have temperatures peaking for the week on
Thursday with highs well into the 70s. Instability may build again
Thursday and Friday with a chance of thunderstorms, followed by a
a chance of a cooling trend for the weekend.
&&
.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 239 AM EDT Sat Apr 18 2026
The line of thunderstorms traveling from west to east will
continue to impact KGRR, KAZO, and KBTL through around 08Z, and
impact KLAN and KJXN from 07Z-10Z. Thunderstorms may contain gusts
25 to 35 knots. MVFR ceilings move in with the thunderstorms and
may fall to IFR levels briefly into Saturday morning. Low
visibilities of 1 to 3 SM are also likely during heavy rain.
Low level wind shear of 40 to 50 knots will be present as a low
level jet impacts the area through 12Z Saturday.
Northwest winds behind the front will build through the day with
gusts 25 to 30 knots, followed by a decrease in winds after
01-03Z. Ceilings will also begin to lift and scatter out Saturday
afternoon and evening.
&&
.MARINE...
Issued at 412 AM EDT Sat Apr 18 2026
Colder air flowing in behind a cold front with west winds gusting
25-30 knots will build 3-6 ft waves today into Sunday morning.
Lower waves are expected Sunday night into Monday with lighter
winds as high pressure moves over the region.
&&
.HYDROLOGY...
Issued at 253 PM EDT Fri Apr 17 2026
Major flooding continues on the Muskegon River. The good news is
that the river at most locations will be cresting within the next 24
hours (Upstream areas of the river including Evart crested earlier
today). It will likely take until late next week for all locations
to come under flood stage, so the recovery process will be slow.
Meanwhile, water levels continue to rise on the Grand River, and
confidence is increasing that this will end up being another minor
flood event, slightly higher and worse than the one that happened
earlier this month, but not a record flood at any locations.
However, some of the lowest and easily flooded locations on the
river like Comstock Park and Robinson Township will have moderate to
possibly major flooding.
A final round of rain moves back into Lower Michigan tonight, and is
expected to drop around one-half inch of rain over a large area,
with locally higher streaks of 1"+ possible at some locations. Given
the saturated soils everywhere, this could result in some renewed
minor flooding, primarily impacting roadways. Thankfully, this
expected rainfall is not anticipated to make the river flooding
significantly worse at any locations. Beyond this next round of
rain, we dry out for at least the better part of a week going
forward, which will be a very welcome chance for the rivers to begin
the slow process of recovering to more normal levels.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 8 AM EDT Sunday for LMZ844>849.
&&
$$
DISCUSSION...CAS
AVIATION...Schoenfeld
MARINE...CAS
HYDROLOGY...AMD
NWS GRR Office Area Forecast Discussion