876
FXUS63 KGRR 160625
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
225 AM EDT Sat May 16 2026
.KEY MESSAGES...
- Storms this morning
- Unsettled into next week; strong/severe storms possible Monday
- Cooler mid to late week
&&
.DISCUSSION...
Issued at 224 AM EDT Sat May 16 2026
- Storms this morning
Regional radar shows a well defined MCV moving ENE across central
Wisconsin. A large area of strong to severe storms was noted with
this MCV. Dewpoints in Wisconsin are in the mid 50s...10 degrees
higher than across the cwa. SPC meso progs suggest that we`ll see
500 or so j/k MUCAPE toward sunrise in southwest Lower. This
should result in a weakening trend as the convection pushes across
the lake. This convection should move across the lake around 400
am and continue eastward, exiting the cwa around 12z. Latest GFS
shows increasing shear between 09-12z suggesting that the storms
won`t weaken too quickly despite lower moisture levels. Indeed,
latest IR loop continues to show cooling cloud tops to the west.
Once the convection moves east of the cwa, there will be a lull.
However, a few of the CAMs point toward renewed showers across
near I-94 late morning. Then, the rest of the day through mid
afternoon Sunday will be dry.
- Unsettled into next week; strong/severe storms possible Monday
A northward moving warm front will move into Lower MI Sunday
afternoon, and this may become a focus for renewed convective
development. Dynamics are somewhat weak; shear values are around
20 kts south of I-96, but closer to 35 knots over the northern
cwa, which is where the RRFS EMC shows some development. Once the
warm front moves north, we`ll be watching trends along the cold
front over Wisconsin/Iowa Sunday night into Monday. Strong to
severe storms will fire along the front across Wisconsin Sunday
night and move east, potentially affecting the northern cwa Monday
afternoon with more development farther south along the frontal
boundary Monday night. Some of these storms could be strong to
severe as well. The convective threat will remain until Tuesday
when the cold front will move through.
- Cooler mid to late week
Air behind the cold front will be in the 60s Wednesday and
Thursday...quite a bit cooler than the 80s ahead of it. However,
temperatures will warm into the lower to mid 70s Friday and
Saturday.
&&
.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1223 AM EDT Sat May 16 2026
Regional radar shows thunderstorms over Wisconsin moving east at
40kts. This places the storms over the lake around 430-500
am...pretty much in line with recent CAM trends. Storms will then
move across the cwa and exit around 12z. The rest of the period
looks to be dry.
As the LLJ moves across the terminals early this morning, some
LLWS is possible from 08z-14z or so. Cigs may briefly fall to MVFR
as the precipitation moves through, then rise back to VFR by late
morning.
&&
.MARINE...
Issued at 224 AM EDT Sat May 16 2026
A weak pressure gradient will result in little if any marine
issues through Sunday. Winds will increase Sunday night as low
pressure over the upper Midwest advances eastward; a small craft
advisory may be needed Sunday night through Tuesday.
&&
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 5 AM EDT early this morning for
LMZ846>849.
&&
$$
DISCUSSION...04
AVIATION...04
MARINE...04
NWS GRR Office Area Forecast Discussion
