965
FXUS63 KGRR 260727
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
327 AM EDT Wed Jun 26 2024

.KEY MESSAGES...

- Patchy Fog This Morning

- Light Rain Late Morning to Early Afternoon

- Showers and storms Friday/Saturday

&&

.DISCUSSION...
Issued at 327 AM EDT Wed Jun 26 2024

- Patchy Fog This Morning

Still quite a bit of low level moisture around with dewpoints
hovering in the mid 60s to low 70s across the area. Shallow fog
development still looks possible early this morning but cloud cover
streaming in from the southwest will act to limit radiational
cooling and extensive fog development. Patchy fog with
visibilities down to 2-4 miles looks likely before sunrise, but
wouldn`t expect widespread dense fog development at this time.

- Light Rain Late Morning to Early Afternoon

A northern stream shortwave and associated cold front will act as a
trigger for a few showers late morning to early afternoon today.
Afternoon instability builds with MLCAPE towards of a few hundred
with decent deep layer shear supporting a few storms. Minimal
mid-level lapse rates and no substantial low level jet winds will
reduce the potential for anything beyond general thunderstorms.

High pressure builds in on the backside of the departing trough
leading to quickly clearing skies during the afternoon and evening.
Conditons stay dry through Thursday.

- Showers and storms Friday/Saturday

A belt of fast westerlies persists across the northern CONUS through
the late week and into next week. Shortwave troughs will bring a
chance of rain late Friday into Saturday and again Monday night
into Tuesday

Surface high pressure center moves east with warm advection pattern
developing by Friday morning. Moisture advection is also underway
with rain chances increasing Friday afternoon and evening as
moisture pools ahead of the advancing cold front. Model consensus
still has the greatest chance for showers and storms late Friday
night.

A severe weather threat may be possible late Friday night into early
Saturday as Lower Michigan is in the warm sector and model soundings
show 30 to 35 knots of shear ahead of the cold front. The limiting
factor is the persistence of convective inhibition Friday night into
Saturday.

Surface high builds in behind the front with fair weather for Sunday
into Monday, then another chance of showers as the next shortwave
trough approaches Monday night and Tuesday.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 132 AM EDT Wed Jun 26 2024

Patchy IFR conditions are possible between about 08Z to 12Z as
some ground fog or low stratus could form. The VFR conditions will
dominate on Thursday. Light and variable winds tonight go west on
Thursday around 10 knots then north Thursday night.

&&

.MARINE...
Issued at 327 AM EDT Wed Jun 26 2024

Going to be monitoring marine and beach conditions closely today for
our typical "Advancing Surface High" scenario. In these types of
situations, northwest to north winds build while channeling and
funneling down the lakeshore against the dune bluffs. Wind speeds
also tend to overperform due to tight thermal packing on the
lakeshore with the cooler waters next to the warmer land surface.
This results in a tighter pressure gradient right along the
lakeshore. Winds will build towards 20 to 25 knots with gusts
towards 30 knots at times. Waves will build this morning into the
afternoon, peaking near 3 to 5 feet this afternoon and evening at
Big and Little Sable Points. We will want to monitor beaches south
of Whitehall for wave development, but the curvature of the
lakeshore may spare more southerly beaches from the worst of the
waves. We will go with SCA and BHS for Mason and Oceana Counties,
but will monitor wave forecast trends closely in case headlines need
to be extended further south.

The northerly winds will make beaches on the north sides of north
piers particularly dangerous due to structural currents and
turbulent wave action. This includes Sterns Park in Ludington and
Mears State Park in Pentwater within the Beach Hazards Statement.
Muskegon State Park, Holland State Park, and North Beach in South
Haven will also need to be monitored closely today.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement from 2 PM EDT this afternoon through
     this evening for MIZ037-043.
MARINE...Small Craft Advisory from 2 PM this afternoon to 11 PM EDT this
     evening for LMZ848-849.

&&

$$

DISCUSSION...Ostuno/Thielke
AVIATION...Ostuno
MARINE...Thielke