398
FXUS63 KGRR 141728
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
128 PM EDT Mon Jul 14 2025

.KEY MESSAGES...

- Chances for Rain Wed/Thu and next Weekend

&&

.DISCUSSION...
Issued at 339 AM EDT Mon Jul 14 2025

- Chances for Rain Wed/Thu and next Weekend

Zonal flow with weak sfc ridging brings fair weather through
Tuesday then rain chances return for mid-week with the approach
of a weak shortwave trough. Showers and storms arrive Wednesday
and persist into Thursday as a cold front moves through. The GFS
has backed off the severe weather threat, now showing rather weak
shear of 20 knots on Wednesday and Thursday. This looks like
another pulse thunderstorm environment and only isolated wind
gusts as a threat. Storm total QPF is only around 0.15
inches average over the forecast area.

Upper ridging across the SE CONUS late in the week with zonal flow
across northern periphery could result in MCS activity making it
into Lower Michigan over the weekend but confidence is low at this
point with location and timing.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 128 PM EDT Mon Jul 14 2025

Canadian wildfire smoke is reducing visibility to 5 or 6 miles in
portions of southern and mid Lower Michigan this afternoon.
Improvement is possible tonight, although consensus of short-term
model guidance leans toward shallow fog development at LAN and
JXN between 08 and 12 Z. Daytime cumulus clouds this afternoon and
tomorrow will have bases around 4,000 feet. Winds mostly below 10
knots.

&&

.MARINE...
Issued at 128 PM EDT Mon Jul 14 2025

Low waves and swim risk through Tuesday with a light southerly
breeze. Thunderstorms are possible between Wednesday and
Thursday. Winds becoming north on Thursday may increase the waves
and swim risk.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Air Quality Alert until midnight EDT tonight for MIZ037>040-
     043>046-050>052-056>059-064>067-071>074.
MARINE...None.

&&

$$

DISCUSSION...Ostuno
AVIATION...CAS
MARINE...CAS