250
FXUS63 KGRR 011858
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
258 PM EDT Sat Jun 1 2024

.KEY MESSAGES...

- Showers Through Late Tonight, Some Patchy Fog Also Possible

- Cool and Cloudy Sunday Morning, Then Partial Clearing/Milder

- Above normal temps early next week

- Cooler and unsettled mid to late week

&&

.DISCUSSION...
Issued at 258 PM EDT Sat Jun 1 2024

- Showers Through Late Tonight, Some Patchy Fog Also Possible

MRMS imagery across the region shows a large batch of showers moving
over Lake Michigan and into our lakeshore area. SPC mesoanalysis
shows no instability present throughout the atmosphere, and this
really isn`t expected to change into tonight. There is a possibility
for some scant elevated instability to approach I-94 where a rogue
lightning strike is possible, but otherwise only showers or a steady
light to moderate rain is expected. This precipitation is being
supported by the right entrance region of an upper jet, and lower
down there is a 500 mb shortwave trough as well as a south to north
oriented low level jet of about 30-35 kts nosing into Lower
Michigan. The 12z HREF LPMM 24 hour precipitation supports potential
for 0.25"-0.50" across our region through early Sunday, with some
localized areas of 0.50"-1.00".

Patchy fog development is possible tonight with an increase in
surface dew points and very light winds as showers traverse the
region, though HREF probabilities for < 1/2 mile are only 20-40%
mainly near and west of US 131. What is more likely is low stratus,
rather than fog.

- Cool and Cloudy Sunday Morning, Then Partial Clearing/Milder

The 12z HREF favors a cool and cloudy start to Sunday with a slow
decrease in low level moisture. Expect temperatures to be stuck in
the low to mid 60s Sunday morning before some partial clearing gets
underway starting with the lakeshore region, then progressing east.
For areas east of US 131, breaks in clouds may not occur until after
18z or so. Have adjusted highs down a bit from previous guidance,
mainly featuring 70-73 across the eastern half of our forecast area
and 73-76 west. There is a low probability for an isolated shower to
pop up mainly east of I-69 Sunday afternoon. Areal coverage looks
minimal enough to largely keep that out of the forecast at this time.

- Above normal temps early next week

It will be quite warm and increasingly more humid early next week
in a southerly flow waa pattern and as a ridge builds over the
eastern CONUS. H8 temps will reach 15-16 C and with some sun high
temps will reach the low to perhaps middle 80s Mon/Tue. A few
showers and storms are possible as well but we expect dry wx to
prevail the majority of the time on both days.

- Cooler and unsettled mid to late week

A cold front will bring scattered showers and thunderstorms on
Wednesday. After fropa a cooler and drier airmass will advect in as
an upper level trough also moves over the Great Lakes region late in
the week.

This will result in a cool and somewhat unsettled wx pattern with
below normal temps by late week into the weekend. Some scattered
showers are expected as well as several upper level disturbances
move through in conjunction with some instability from daytime
heating and with relatively cool air aloft tied to the upper trough
axis. By Friday high temps will struggle to reach the middle to
upper 60s.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1232 PM EDT Sat Jun 1 2024

VFR conditions will continue at all the terminals this afternoon.
Rain showers will develop late this afternoon and then continue
through most of the overnight period. An isolated storm is
possible late this afternoon and evening but there is not enough
potential for thunderstorms to warrant inclusion in any of the
terminal forecasts at this time.

Conditions will slowly deteriorate to MVFR then IFR overnight due
to lowering cigs. Showers will gradually taper off during the
early to mid morning hours Sunday with mainly IFR conditions
Sunday morning which will slowly improve to MVFR by late morning.

&&

.MARINE...
Issued at 258 PM EDT Sat Jun 1 2024

Some patchy fog is possible this evening through early Sunday
morning. Probabilities look low for any dense fog formation.
Otherwise, expect wave action to be 1-2 ft for the majority of the
next several days and winds generally 5-15 kts.

&&

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

&&

$$

DISCUSSION...Laurens/Hoving
AVIATION...Laurens
MARINE...Hoving