030
FXUS63 KGRR 031428
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1028 AM EDT Mon Jun 3 2024

.KEY MESSAGES...

- Morning Fog, Warm and Rain-Free Daytime, Chance Storm Tonight

- Medium/High Confidence in evolution of upper troughing this week

&&

.UPDATE...
Issued at 1028 AM EDT Mon Jun 3 2024

We were able to let the marine dense fog advisory go as planned
this morning without any issues. The patch of dense fog along the
shoreline was pushed offshore by the increasing wind from the SSE.
Winds should remain high enough that the fog should not become an
issue there in the foreseeable future.

With regards to the forecast for the land areas today/this
evening, the already low shower/storm chances continue to trend
down for the area. The models indicate that the sufficient
instability will mainly stay over Wisconsin through early evening.
By the time what is left over from the Wisconsin convection and
short wave arrives in the NW corner tonight, any diurnal
instability will be mostly gone.

&&

.DISCUSSION...
Issued at 342 AM EDT Mon Jun 3 2024

- Morning Fog, Warm and Rain-Free Daytime, Chance Storm Tonight

Airport observations, webcams, and nighttime microphysics satellite
imagery indicate regions of fog in a few different parts of the
area, and variable visibilities within those regions including
occasional dips to a quarter mile. Fog should mix out over land by 8
or 9 AM with a fair amount of sunshine today.

Keeping the forecast rain-free until after 7 or 8 PM based on the
00Z HREF, which is slightly later with the timing than the previous
12Z run. Convection from Iowa to Wisconsin and northern Illinois
today will struggle to make it into Michigan with slight ridge
amplification over the eastern Great Lakes and a lack of upper-level
jet support. Somewhat better dynamics and 850-700 mb moisture
advection arriving after 8 PM will provide better chances of a
thunderstorms from Wisconsin being maintained, especially northwest
of Grand Rapids. CAPE less than 500 J/kg would be a limiting factor
especially with eastward extent. Each model within the HREF has its
own take on the decay of the Wisconsin convection over Michigan
tonight, so confidence in the details is low.

- Medium/High Confidence in evolution of upper troughing this week

There remains good agreement among model solutions with the closed
upper low approaching from the northwest this week. This low figures
in the evolution of persistent troughing across the Great Lakes by
the end of the week with lower 500 mb heights and low level
northwest flow indicating cooler than normal temperatures into early
next week.

As far as rain chances,Tuesday will see some showers and
thunderstorms in moist southerly flow ahead of the upper low with
the best chances on Wednesday as a cold front will focus rain and
embedded thunderstorms. Deep layer shear is progged to be 25 to 30
knots on Wednesday afternoon so some organized convection is
possible, although severe storm threat appears low.

The upper low will bring showery and seasonably cool weather for
several days from late week into early next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 715 AM EDT Mon Jun 3 2024

Patchy LIFR and IFR conditions will go to VFR this morning as fog
and low stratus dissipate. VFR conditions expected this afternoon
and evening. There could be scattered showers and thunderstorms
this evening across western Lower Michigan in the vicinity of MKG.

South to southeast winds today AOB 10 knots.

&&

.MARINE...
Issued at 342 AM EDT Mon Jun 3 2024

Areas of dense fog are present along the shore especially between
Holland and Ludington, as indicated by satellite images and webcams.
Expecting the fog should diminish later this morning as southerly
winds increase. Waves build to 1 to 3 feet today, highest near the
Sable Points. May have to contend with thunderstorms crossing the
lake after 7 PM, though models suggest they will be on a weakening
trend. Additional thunderstorms could affect the nearshore waters
between Tuesday evening and Wednesday morning.

&&

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

&&

$$

UPDATE...NJJ
DISCUSSION...Ostuno/CAS
AVIATION...Ostuno
MARINE...CAS