698
FXUS63 KGRR 191858
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
258 PM EDT Wed Aug 19 2026

.KEY MESSAGES...

- Drier and Comfortable Air on Thursday

- Showers and Chance of Scattered Thunderstorms Late Week

&&

.DISCUSSION...
Issued at 258 PM EDT Wed Aug 19 2026

- Drier and Comfortable Air on Thursday

The more humid air has been nudged south of the area along a weak
cold front, and dew points are trending into the upper 40s to 50s
for much of the area, especially in Central Michigan. With dew
points still in the 60s this afternoon near I-94 and favorable
lapse rates 850-700 mb, there is a slight chance for low-topped
and isolated showers to develop this afternoon or tonight,
especially closer to Jackson, as portrayed in a few of the HREF
member CAMs.

- Showers and Chance of Scattered Thunderstorms Late Week

Global models continue to depict an upper-level trough digging
from western Hudson Bay toward Michigan Fri-Sat, then cutting off
a low over the central/northeast Great Lakes region Sun-Mon.
Slightly warmer and more humid air should briefly nose back in on
Fri before the next weak cold front passes through Fri night.
Scattered showers and thunderstorms may develop in the vicinity of
the front amid CAPE around 1000 J/kg (some ECE members depict
MUCAPE as high as 2000 J/kg). Deep layer shear may be relatively
modest, around 20 knots, limiting the severe weather potential.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 145 PM EDT Wed Aug 19 2026

VFR conditions will generally prevail this afternoon across West
Michigan, with only scattered 3-4kft CU anticipated. The
exception will be at BTL/LAN/JXN, where occasional broken MVFR
ceilings just below 3kft will be possible through roughly 20-21Z.
Otherwise, expect CU to dissipate this evening, with only some
patchy mid/high clouds expected thereafter, mainly along the I-94
corridor /AZO-BTL-JXN/. Mainly clear skies /VFR wx/ expected
Thursday.

Winds will remain light through the TAF period. Generally W-NW
flow this afternoon will veer to NE by late tonight and continue
Thursday.

&&

.MARINE...
Issued at 258 PM EDT Wed Aug 19 2026

Waves and swim risk remain low with light winds tonight and
Thursday. Then Friday and through the weekend, there will likely
be some medium-high swim risk areas, with winds increasing in the
vicinity of low pressure slowly trekking across the Great Lakes.
Beaches north of Grand Haven on Friday should have the higher swim
risk, due to south winds. Northwest winds are favored Saturday and
Sunday. Scattered thunderstorms are possible over the lake from
late Friday into early Saturday.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.

&&

$$

DISCUSSION...CAS
AVIATION...Smith
MARINE...CAS