-- Discussion containing changed information from previous version are highlighted. --
990
FXUS63 KGRR 092355
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
755 PM EDT Sun Jun 9 2024

.KEY MESSAGES...

- Quiet Weather Early This Week...Outside of the High Swim Risk

- Warming Trend into Mid-Week

- Rain Chances Tuesday Night and Thursday Night

&&

.DISCUSSION...
Issued at 329 PM EDT Sun Jun 9 2024

- Quiet Weather Early This Week...Outside of the High Swim Risk

The main sensible weather to be concerned with will be the area of
post frontal low clouds that will sag south through the area
tonight and Monday morning. A cold front is situated off to our
north this afternoon across far Northern Lower Michigan. The front
will make steady progress to the south tonight pushing through the
entire area bringing drier/cooler air as well as a band of low
clouds. The clouds should clear the area in the mid to late
morning on Monday near I-94. We do have a very small chance for an
isolated shower (20 pct) this evening near Highway 127, but this
threat is extremely small. Most areas should stay dry. Monday
night looks clear and cool with lows in the upper 30s to middle
40s.

See the marine section below for details on the high swim risk
tonight and Monday. All area beaches will be affected with the
worst conditions in the afternoon.

- Warming Trend into Mid-Week

A cooler start to the week Monday, then return flow Tuesday brings a
warming trend as surface ridging builds. Expect a continued warming
trend into the end of the week as the ridge axis moves over the
Great Lakes. By Thursday the thermal ridge moves overhead with temps
to 13-16C resulting in highs in the mid to upper 80s.

- Rain Chances Tuesday Night and Thursday Night

A weakening front will bring chances for rain Tuesday night across
the northern CWA as a shortwave moves north of the area. Dewpoints
surge Wednesday and Thursday ahead of an approaching surface low
supporting better rain chances Thursday into Friday. Precipitable
water surges to 1.5 to 2 inches presenting the possibility for heavy
rain, while MUCAPE builds to 1000j/kg. A fair amount of uncertainty
exists on overall evolution, but showers and storms look possible
for the Thursday night time window.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
-- Changed Discussion --
Issued at 755 PM EDT Sun Jun 9 2024

A period of MVFR cigs is expected late tonight into early Monday
behind a cold front which is currently sinking south through Lwr
MI. The duration of the lower ceilings (roughly 1800-2500 ft) is
expected to last around 4 to 6 hours, and mostly between 06Z and
12Z. Otherwise VFR prevailing this evening and for most of
Monday. Gusty northerly winds will relax somewhat after sunset
then pick up again Monday afternoon to 10-20 kts.
-- End Changed Discussion --

&&

.MARINE...
Issued at 329 PM EDT Sun Jun 9 2024

Earlier this afternoon we update the Beach Hazard Statement to
include Muskegon County. We also extended our northern beach,
Grand Haven northward, all the way through the day on Monday for
hazardous conditions.

The event tonight into Monday (especially Monday) is our classic
"advancing high setup." The high building in from the northwest
enhances the gradient in place along our shoreline, given a
thermal low usually forms over the Lower Peninsula in the
afternoon. As is usually the case, the winds and waves peak around
400pm or so with stronger winds working down the shoreline. High
resolution modeling suggest our entire lakeshore will see at least
18kt winds Monday afternoon with a core around 25 knots centered
near Muskegon and Ottawa Counties in the afternoon. Our local wave
guidance suggests the entire lakeshore will see 4-6 footers in the
late afternoon, hence the extension in time and space. Winds and
waves will subside significantly Tuesday night.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
MI...Beach Hazards Statement through Monday evening for MIZ037-043-
     050.
     Beach Hazards Statement through Monday evening for MIZ056-064-
     071.
MARINE...Small Craft Advisory until 11 PM EDT Monday for LMZ844>849.
-- End Changed Discussion --

&&

$$

DISCUSSION...Duke/Thielke
AVIATION...Meade
MARINE...Duke