697
FXUS63 KGRR 180735
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
335 AM EDT Thu Jun 18 2026
.KEY MESSAGES...
- Cooler Than Normal with Weekend Rain Shower Chances
&&
.DISCUSSION...
Issued at 335 AM EDT Thu Jun 18 2026
- Cooler Than Normal with Weekend Rain Shower Chances
Broad and low amplitude upper level troughing across the northern
CONUS will keep our temperatures several degrees cooler than
normal (normal high temperatures are now around 80). Expecting
25-30 mph gusts today and 20-25 mph gusts on Friday. Can`t rule
out a few isolated showers or sprinkles in eastern locations this
afternoon, and a few more crossing Lake Michigan late this
evening.
The chance of rain showers has increased a little to about 30-40
percent for early Saturday morning, and persisting into afternoon
for locations away from Lake Michigan. A couple of weak shortwaves
propagating through the mid-upper level northwesterlies will be
the impetus for such activity, but very little instability will be
a limitation. The 12 Z global model ensemble systems offered just
a 15-20 percent chance of rain totals over a quarter inch.
Still a boom or bust scenario for rain Sunday into Sunday night,
as a southern stream shortwave trough ejection from the western
CONUS leads to surface low development tracking from the central
Plains toward the southern Great Lakes or Ohio Valley. The ENS,
GEFS, and GEPS remain mixed with rain totals between zero and 1-2
inches, which is mainly dependent on the track of the low. For
now, the chance of rain Sunday is about 30 percent around US-10
and 60 percent around I-94.
&&
.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 203 AM EDT Thu Jun 18 2026
Thunderstorms now N-E of Mount Pleasant (MOP) are moving E, and
that will likely be the last of the storms for this weather
system. Going into Thursday, likely a mix of IFR and MVFR ceilings
this morning trending above 2,000 ft between 15 and 17Z, then
scattering out to VFR later in the day. Gusty west-northwest winds
are expected until about 00 Z.
&&
.MARINE...
Issued at 335 AM EDT Thu Jun 18 2026
West-northwest winds 15 to 25 knots gusting to 30 knots this
morning will build waves 3 to 6 feet Manistee to Whitehall and 5
to 8 feet Whitehall to St Joseph. The large waves and strong
currents will make for hazardous swimming conditions at all
beaches. Winds gradually relax and waves subside toward a moderate
swim risk by late afternoon. A moderate to high swim risk is
again expected Friday morning to early afternoon.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement through this afternoon for MIZ037-043.
Beach Hazards Statement through this afternoon for MIZ050-056-
064-071.
MARINE...Small Craft Advisory until 6 PM EDT this evening for LMZ844>847.
Small Craft Advisory until 4 PM EDT this afternoon for LMZ848-
849.
&&
$$
DISCUSSION...CAS
AVIATION...CAS
MARINE...CAS
NWS GRR Office Area Forecast Discussion
