842
FXUS63 KGRR 011711
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
111 PM EDT Tue Jul 1 2025

.KEY MESSAGES...

- Spotty Chances for Showers/Storms Wednesday through Friday

- Cold Front to Bring Showers/Storms Saturday night into Sunday

- Near Normal Temperatures Today then Slow Warming Trend

&&

.DISCUSSION...
Issued at 345 AM EDT Tue Jul 1 2025

- Spotty Chances for Showers/Storms Wednesday through Friday

We look to be precipitation free today as drier air settles in on
westerly winds. On Wednesday however, during the afternoon and
evening, we may see some isolated/scattered shower and
thunderstorm activity. The forcing for the precipitation looks to
be via 1) a lake breeze boundary pushing into interior portions
of the Lower Peninsula as well as 2) a weak stationary boundary
sagging south out of Northern Lower. Precipitation coverage is not
expected to be widespread, but both the SREF and the HREF are
showing this potential (two trusted sources).

On Thursday the weak boundary is still in the vicinity and the
SREF once again is indicating some weak activity bubbling up
during the heat of the day. Again, not expecting widespread
precipitation and in fact most areas will likely remain dry.

Friday the models bring the heat and humidity back into the area
in full swing. As the moisture moves back in, it appears as though
we have some small chances for warm frontal showers and storms.

- Cold Front to Bring Showers/Storms Saturday night into Sunday

Better chance for showers and storms will come Saturday night into
Sunday as a cold front moves into the area from the north and
west. The models have slowed this front up by about 12 hours in
the latest runs. The front is being driven by a weak shortwave
trough in the mid levels which is losing amplitude as it moves in.
That said, it is the best forcing we see in the 7 day forecast.
Typical mid summer forecast this morning where there is very
little forcing throughout with conditions being dominated by weak
fronts and thermodynamics. Chances for rain mid week is only 20-30
pct. Chances Saturday night are 40-60 pct.

- Near Normal Temperatures Today then Slow Warming Trend

We will be less humid today and slightly cooler with highs back
into the lower 80s which is near normal. Ridging will build aloft
as we head into the end of the week. 850mb temperatures will rise
as well from around +13C today to +18 to +20C Friday into
Saturday. Highs will nudge up each day as we move forward with
lower 90s possible on Friday and likely Saturday.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 108 PM EDT Tue Jul 1 2025

Few to scattered VFR diurnal cu will dissipate with sunset
leaving clear skies overnight.

&&

.MARINE...
Issued at 108 PM EDT Tue Jul 1 2025

High pressure will remain overhead for the next few days resulting
in waves aob 2 feet. As the high moves east Friday, southwest
winds will increase and waves will respond by building to 2 to 4
feet late late Friday into Saturday.

&&

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

&&

$$

DISCUSSION...Duke
AVIATION...04
MARINE...04