416
FXUS63 KGRR 042044
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
444 PM EDT Fri Jul 4 2025

.KEY MESSAGES...

- Small chance of a shower/storm through Saturday; Otherwise Hot

- Shower and storm chances increase Saturday night into Sunday night

- Dry Monday and Tuesday; Rain Chances Wednesday-Thursday

&&

.DISCUSSION...
Issued at 243 PM EDT Fri Jul 4 2025

- Small chance of a shower/storm through Saturday; Otherwise Hot

The SW portion of the area had to contend with some showers and
storms that lingered longer than expected this morning. Those have
since fizzled out quickly as the low level jet and moisture return
have weakened considerably over the last few hours.

We will be left with only small 20-30% chcs of a shower or storm
this afternoon east of U.S.-131. The atmosphere is still quite
unstable with the heat and moisture still around, and upper ridge
building over the area. Forecast soundings show the mid levels
warming a bit with the upper ridge building overhead later this
afternoon and evening. This will essentially cap the atmosphere, and
reduce the small chances of rain even more. This will be the case
through Saturday.

The clouds have limited the heating a bit today for the southern
half of the area. We will see clouds scatter out a bit, and allow
for temps to warm to 90F today. 850 mb temps warming to around 20C
with the heat dome overhead will allow temps to warm into the lower
90s for Saturday. Dew points are not going to be too oppressive in
the low to mid 60s F. This should limit the potential for any type
of heat headlines being needed with heat indices expected to stay
below 100F.

- Shower and storm chances increase Saturday night into Sunday night

The second half of Saturday night will see the cold front to our NW
drop in late. We will see shower/storm chances arrive over the NW
corner of the forecast area after midnight, and then spread SE
through Sunday morning.

The timing of the front and rainfall being focused on late Saturday
night and Sunday morning for a majority of the forecast area will
limit any severe potential a bit. The lack of strong instability
without any help from a diurnal boost will also keep things mostly
tame. In fact it may limit rainfall for the Central and Northern
portions of the forecast area.

Southern areas will see the best instability build with some heating
taking place before the rain/front will move in. Sfc based LI`s are
forecast to drop to around -4 to -5C and MU CAPE increasing to over
1,000 J/kg. Even with the best instability, deep layer shear values
are wimpy, with only 15 to 20 knots of 0-6km shear. This situation
looks like it will mainly be a beneficial rain, with little to no
chance of severe weather.

The front will sink south of the area Sunday night, taking the
rainfall with it.

- Dry Monday and Tuesday; Rain Chances Wednesday-Thursday

Once we see the front sink south of the area, dry and cooler weather
should return to the area for Monday. The upper heights drop a bit
as the weekend upper ridge gets flattened well.

Sfc ridging will then dominate over the area Monday through Tuesday.
A flow from the north and east will bring in slightly cooler
temperatures, and much drier air. This will hold over the area until
at least Tuesday evening as the sfc ridge slips east of the area.

Rain chances then look to return to the area for Wednesday and
Thursday, with cooler temperatures holding in over the area. The
upper jet will be dropping in over the Upper Midwest, and allowing a
short wave trough to move over the area. This system will not have
much moisture to work with as we do not see a moist flow set up from
the Gulf ahead of the sfc front. The short wave will mostly act with
diurnal instability to fire a few showers and storms Wed and Thu
afternoons.

There is some uncertainty as to how quick this system moves out
toward the end of next week. We feel it is more likely to move out
by next Friday, but can not rule out it sticking around a little
longer.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 420 PM EDT Fri Jul 4 2025

Showers and storms will continue to move to the east. Chances
 for showers and storms will continue to dwindle as the evening
continues. Have put Prob30 in through 21Z at LAN and 00Z at JXN
for any storm potential. Winds will remain gusty through the first
half of the afternoon and gusts will slacken into the evening
becoming calm between 23Z to 01Z. An inversion capable of trapping
smoke will settle in late this afternoon into the evening. VFR
will dominate the pattern overall

&&

.MARINE...
Issued at 243 PM EDT Fri Jul 4 2025

We will be issuing Small Craft Advisories and Beach Hazards
Statements for the weekend with this afternoon`s forecast cycle.

No problems with winds and waves through Saturday morning with a
lighter pressure gradient in place. Winds will then increase for the
northern half of the marine zones beginning Saturday afternoon. This
takes place as a result of the cold front pressing down closer to
the area. The area of concern for Saturday will be north of Muskegon
with the increasing flow from the SW. The winds will then spread
down a bit further Saturday night to around Holland. Winds will then
switch to become from the NW on Sunday as the cold front moves
through. Areas south of Holland do not look to be as strong as the
north at this time.

Once the wind and waves subside on Sunday afternoon/evening, winds
should stay on the lighter side for a good period of next week.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement from Saturday afternoon through Sunday
     evening for MIZ037-043-050.
     Air Quality Alert until midnight EDT Saturday night for MIZ050-
     056-057-064-071.
     Beach Hazards Statement from Saturday evening through Sunday
     evening for MIZ056.
MARINE...Small Craft Advisory from 8 PM Saturday to 8 PM EDT Sunday for
     LMZ846.
     Small Craft Advisory from noon Saturday to 8 PM EDT Sunday for
     LMZ847>849.

&&

$$

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