792
FXUS63 KGRR 091934
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
334 PM EDT Wed Jul 9 2025

.KEY MESSAGES...

- Showers and storm this afternoon, small chance for severe

- Dry weather Tomorrow

- Rain chances continue to expand, Friday into Saturday


&&

.DISCUSSION...
Issued at 330 PM EDT Wed Jul 9 2025

- Showers and storm this afternoon, small chance for severe

 Storms have spring as a low continues to move through Michigan
dragging a cold front through southern lower this afternoon and
evening. Weak supercells with damaging wind is the primary threat,
with the best DCAPE through central Michigan, north of I 96. Shear
remains weak though SFC based CAPE is over 2000 J/kg.
 These storms will continue to form along the frontal boundary,
with southwesterly flow ahead of the front, and westerly flow
behind it. The front will continue to move to the east through the
evening. With strong moisture through the mid levels, heavy
rainfall remains a concern, and as such WPC has southern lower in
an excessive rainfall outlook. Expect periods of heavy rainfall
with any thunderstorm, though only minor flooding is possible.
 The most likely location for any flooding would be just east of
Jackson and Lansing, where 2 to 3 inches of rainfall fell
overnight.
 Strong storms will be possible through the afternoon and into the
early evening. CAMS concur that as the boundary moves to the east
by mid evening, convection will cease.

- Dry weather Tomorrow

 As the cold front moves to the east overnight, skies will clear.
Patchy fog should form overnight due to moist low levels,
especially in regions that received recent recent rainfalls. Calm
winds will also aid in fog development. While not expected dense
fog, it is possible, especially in low lying regions. Fog should
lift/dissipate by mid morning. With high pressure overhead fair
weather with highs in the 80s is a foregone conclusion.

- Rain chances continue to expand, Friday into Saturday

Models continue to show the high pressure weakening into Friday as
a negatively short wave moves into the region daytime Friday.
This is out ahead of a deepening low that will be moving through
the Great Plains. A moisture boundary through the mid levels could
feed into this short wave and, given the summer sunshine could
allow for some scattered showers Friday afternoon. The previously
mentioned low should be engulfed by a deeper level low moving
through southern Canada and should trek through the northern Great
Lakes bringing widespread, beneficial rains through Saturday.
Latest QPF has upwards of a half on a inch, though given that
NAEFS mean PWATS have 1 to 1.75 over the area through most of
Saturday, those values could be higher. Deep layer shear remains
present and given large SFC based CAPE potential, organized
convection remains possible Saturday.

 Front should move to the east with drier air filtering into the
region in its wake. Expect warm, fair summer weather to return
late Sunday into early next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 136 PM EDT Wed Jul 9 2025

Storms continue to form through southern lower Michigan. Have
adjusted TEMPO`s for the TAF sites. Expected periods of TSRA at
GRR, LAN, BTL and JXN until around 21Z. Storms will continue to
move eastward with all storm threat ending around 00Z. Periods of
IFR cigs and vsbys will be possible overnight, primarily at JXN
and MKG. Conditions will improve between 13Z and 15Z tomorrow with
VFR then dominating.

&&

.MARINE...
Issued at 330 PM EDT Wed Jul 9 2025

Winds and waves are building as northerly flow continue to
strengthens behind the front. The northerly flow with beneficial
fetch will continue to build through the afternoon and through
the early evening as the gradient tightens.
 Winds will slacken overnight as a high builds into the area.
Expect waves to subside overnight with fair winds and waves
tomorrow.


&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 2 AM EDT Thursday for MIZ050-056-
     064-071.
MARINE...Small Craft Advisory until 2 AM EDT Thursday for LMZ844>847.

&&

$$

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