223
FXUS63 KGRR 112347
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
747 PM EDT Tue Aug 11 2026

.KEY MESSAGES...

- Showers and storms moving to the South; Patchy fog overnight

- Chances for storms tomorrow

- Next chance for Showers/storms over the weekend

&&

.DISCUSSION...
Issued at 303 PM EDT Tue Aug 11 2026

- Showers and storms moving to the South; Patchy fog overnight

 The quasistationary boundary continues to sag southward and will
push any showers/storms in that direction. There has been some
light rain along the I 94 corridor, with the anvil from the
thunderstorms through southern Michigan bringing some rumbles of
thunder and vicinity lighting to that region. However, the storms
themselves continue their southward trek toward the southeast.
 Light winds, a moist surface layer and recent rainfall is a
recipe for patchy fog overnight into Wednesday morning. Expect
this fog to be dense at times and will linger through the morning
commute.

- Chances for storms tomorrow

Though there is a signal for decent CAPE values from the SFC
moisture and daytime temperatures into the 80s, the atmosphere is
fairly stable, especially since the boundary remains to the south.
Latest HREF does show the potential for a weak mid level trough
and some shear through northern lower Michigan in the afternoon.
That could take advantage of the 1K J/kg of CAPE Wednesday
afternoon. For those reasons, SPC has a ribbon of marginal risk of
severe storms through the central and northern half of Lower MI
tomorrow afternoon and evening.


- Next chance for Showers/storms over the weekend

The large upper level low over northern Canada continues to send
waves through Michigan through the week. However, we remain
fairly stable through the latter half of the week with
temperatures at, to below normal into the weekend. A large upper
level low will move into the the Great Lakes region through the
area mid to late weekend with chance for rain into Sunday.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 747 PM EDT Tue Aug 11 2026

Patches of clouds at 1,500 to 2,500 feet exist this evening. The
trend toward mostly clear skies tonight with light winds, and
rather high dew points compared to expected low temperatures, is
a setup for fog early Wednesday morning. The 18Z REFS gives about
a 30-40 percent chance for quarter-mile visibility between 09 and
12 Z. Absent of that, plain IFR is favored regardless. Conditions
improve gradually between 12 and 15 Z, then daytime cumulus may be
on the edge of MVFR with a chance of an isolated afternoon
shower.

&&

.MARINE...
Issued at 312 PM EDT Tue Aug 11 2026

Showers and storms will move to the south this afternoon and
evening. A typical mid summer weather pattern will continue the
next few days. Light winds will continue. Expect sunshine and
some of our warmest water temperatures. Winds and waves will
remain fairly light through tomorrow.

&&

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

&&

$$

DISCUSSION...Ceru
AVIATION...CAS
MARINE...Ceru