660
FXUS63 KGRR 060725
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
325 AM EDT Sat Jul 6 2024

.KEY MESSAGES...

- Isolated Showers and Storms Today

- Another round of showers/storms possible early next week

&&

.DISCUSSION...
Issued at 325 AM EDT Sat Jul 6 2024

- Isolated Showers and Storms Today

Fairly tranquil weather expected over the weekend as upper
troughing prevails, but model soundings show a drying trend
through Sunday. There will be enough moisture and diurnally
driven instability to pop some showers and isolated thunderstorms
today with the greatest coverage this afternoon across interior
zones. With westerly low level flow we expect a lake shadow and
little or no showers across the western zones.

Shower activity diminishes and ends Saturday evening with the loss
of insolation. Model soundings are drying out and surface ridging
builds in on Sunday, so we will continue the dry forecast.

- Another round of showers/storms possible early next week

Another deep trough will swing into the region late Sunday night
through Monday. Latest mid range models are in good agreement on
the position and track of this positively tilted upper level
trough. Copious amounts of mid level moisture will accompany this
trough and coupled with good 500 mb vorticity there should be
enough instability for showers and storms in the Tuesday
timeframe.

The biggest question is how much gulf moisture will
this system tap into. Given the latest ensembles, while there is
anomalous moisture moving through the region by mid week, the best
moisture will be just east of the region. However there are some
outliers that open the possibility for heavier rainfall.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 143 AM EDT Sat Jul 6 2024

Cool, moist flow will continue overnight. Lows in the 60s and a
capping inversion will couple with the rainfall from earlier an
MVFR to IFR cigs are expected between now and 12Z. MKG and BIV are
already IFR with GRR, AZO and BTL expected to have periods of IFR
now through 12Z. Cigs will slowly lift and improve by 15Z. The
cool, moist flow will continue today and showers will be possible
this afternoon at LAN. Otherwise, VFR will then dominate the
pattern.

&&

.MARINE...
Issued at 325 AM EDT Sat Jul 6 2024

Winds and waves are expected to remain non-hazardous to boaters
and swimmers over the weekend and into next week. The chance for
thunderstorms is also low until early next week.

&&

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

&&

$$

DISCUSSION...Ostuno/Ceru
AVIATION...Ceru
MARINE...Ostuno