904
FXUS63 KGRR 022324
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
724 PM EDT Sun Jun 2 2024

.KEY MESSAGES...

- Chance of rain Monday afternoon and night

- Cold front to bring showers and a few storms Wednesday

- Cooler and unsettled late week into the weekend

&&

.DISCUSSION...
Issued at 242 PM EDT Sun Jun 2 2024

- Chance of rain Monday afternoon and night

Cu/stratocu will decrease as heating wanes late in the day,
leading to partly cloudy sky overnight.

Our next chance of rain is Monday afternoon. A weak short wave is
going to move east from the northern Plains in weak zonal flow. A
30 kt low level jet ahead of it will push moisture into the
northwest cwa late in the day and evening. Instability will also
increase throughout the day as mid level lapse rates climb. As the
short wave approaches, we`ll likely see some showers/storms
develop; highest PoPs will be across the northwest cwa closer to
the better moisture and dynamics. HREF localized probability
matched mean (LPMM) suggests a quarter inch to over an inch of
rain possible across the northwest cwa with considerably less
elsewhere. Precipitation will diminish late Monday night.

Highs Monday will be well above normal in the lower to mid 80s.

- Cold front to bring showers and a few storms Wednesday

Warm and humid conditions are expected Tuesday through early Wednesday
out ahead of the cold front in the southerly flow waa pattern. H8 temps
should reach 17-18 C Tue afternoon. Guidance has trended warmer and
we now expect high temps to reach well into the 80s Tuesday with
mild temps in the 60s Tuesday night in the humid airmass.

A cold front will bring showers and a few thunderstorms Wednesday.
At first glance some parameters would appear favorable for severe wx
potential. However cold frontal timing is not favorable as it will
be coming through Wednesday morning with lots of clouds and showers
in place. Therefore we will have very limited instability for any
convection to occur and guidance favors areas well east of our area
for the better chance for convection and certainly any svr wx
potential.

- Cooler and unsettled late week into the weekend

An upper trough axis settles in late in the week resulting in much
cooler and somewhat unsettled wx and below normal temps by then.
Some scattered showers are expected as several upper level
disturbances pass through coincident with some instability from
daytime heating and cool air aloft.

Initially the relatively better chance for mainly diurnally drive
pcpn will be north to ne of our area in closer proximity to the
upper low center and where mid to upper level dynamics will be
stronger. However by the weekend stronger mid to upper level
disturbances will move in from the wnw keeping our wx cool and
unsettled with below normal temps and some scattered showers.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 724 PM EDT Sun Jun 2 2024

We continue to see improving conditions this evening, with the low
clouds from earlier lifting up and scattering out. Still a decent
amount of cumulus development, but it is all VFR at this point and
is diminishing.

The main impact to aviation interests in this forecast period will
be the potential for fog potential tonight. Dew points in the
boundary layer remain a bit high. We do not see a significant
amount of dry air moving in. Crossover temperatures are in the
upper 50s and lower 60s, which we should see exceeded below these
values at all sites. The lakeshore (KMKG) has the best chance with
the moist flow off of the lake. Also, the models seem to be
favoring the East where the limited drier air has not reached
quite yet.

We foresee plenty of IFR, and even VLIFR along the lakeshore and
to the east. Always tough to tell with fog forecasting, but that
is the trend we expect. The fog will burn off/mix out quickly by
mid Monday morning.


&&

.MARINE...
Issued at 242 PM EDT Sun Jun 2 2024

High pressure overhead is producing light winds at the lake and
this will continue for the next few days. The pressure gradient
and corresponding surface winds may tighten a bit Wednesday when a
cold front approaches.

Thunderstorms are possible Monday which would pose a threat to
boaters.

&&

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

&&

$$

DISCUSSION...Laurens/04
AVIATION...NJJ
MARINE...04