-- Discussion containing changed information from previous version are highlighted. --
656
FXUS63 KGRR 302327
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
727 PM EDT Thu May 30 2024

.KEY MESSAGES...

- Clear tonight, warmer Friday

- Warm and unsettled weather pattern through Wednesday

- Pattern change on the horizon late next week

&&

.DISCUSSION...
Issued at 251 PM EDT Thu May 30 2024

- Clear tonight, warmer Friday

Surface analysis shows high pressure centered over Lake Michigan and
clear skies stretching from Ontario west to Iowa. Forecast concerns
through Friday night are minimal.

Clear skies are expected again tonight and given dewpoints in the
lower 40s, we`ll see temperatures drop into the 30s across the
northern cwa. Patchy frost is possible in low lying areas near US-
10. However, as the high drifts east overnight, a light south wind
will develop prior to sunrise; temperatures won`t be as cold tonight
as they were last night.

Another sunny day is expected Friday and temperatures will be above
normal in the mid to upper 70s. As the high continues drifting east
Friday night, a developing low in the mid Mississippi Valley will
move toward the Great Lakes, aided by a deeper upper trough over
western Ontario. The effect of this will be increasing clouds Friday
night. The increase in cloud cover will help temperatures bottom out
in the mid 50s.

- Warm and unsettled weather pattern through Wednesday

Saturday continues to feature our next chance of rain for the area.
The upper ridge giving us our nice days today and Friday will have
shifted east of the area by then. The best chance for rain on
Saturday will be the further south you go. This is the result of a
split flow between the northern stream north of the state, and a
southern stream wave moving just north of the Ohio River Valley. The
deepest moisture and instability will stay down there with the low
staying south of the area. In fact, it looks like most of the rain
the area sees will be just showers, except maybe right along the
southern border where some elevated instability will approach.

That system will clear out of the area by daybreak on Sunday. That
should allow for a mainly dry day, with continued warm temperatures.
The nearly zonal flow will keep the warmer weather in place and
colder air bottled up north of the border. Short wave ridging will
move across the area, bringing additional subsidence. The exception
to this will be maybe a pop up shower across the SE where some
residual low level moisture holds on longer in the wake of
Saturday`s system.

The next wave in this zonal upper air pattern now looks to arrive
later on Monday, bringing additional shower/storm chances. The upper
flow will be buckling a little more with stronger energy moving in
over the Pacific NW. The Monday system looks like it will have a bit
more widespread shower/storm activity than Saturday, but still
nothing significant. The more noteworthy thing about this system is
that the buckling of the upper flow will allow a bit more
instability to spread north over the area and result in more storms.
The low level moisture feed out of the Gulf is still not
impressive, and there does seem to be still somewhat a split in the
upper jet.

The Wednesday/Thursday system looks to be a bit more dynamic as the
upper flow continues to amplify with the stronger Pacific energy
entering the picture over the country. This far out the details are
still a bit unclear, but it does appear that we will see a system
with more potential impacts with regards to severe weather potential
whenever the timing is. The timing will all depend on how and when
the upper low closes off. There is good agreement that this looks to
occur by the ensemble means. When the front comes through, it should
have a good feed of instability and jet support with it. It also
could come through as early as Wednesday, or could wait until
Thursday.

- Pattern change on the horizon late next week

Whenever the aforementioned upper low cuts off and brings the
potential for impactful weather in, the result after it happens
looks to be a cooler and showery period. The upper cold pool will be
overhead with short waves rotating around it. This means
temperatures dropping to average to below average levels, and
occasional chances for rain showers and maybe some thunder.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
-- Changed Discussion --
Issued at 727 PM EDT Thu May 30 2024

High pressure holds strong over the region. Clear skies with calm
winds are expected through the night, then wind pick up to 5-10
knots Friday afternoon. Overall, expect continued VFR with no
aviation concerns to note.
-- End Changed Discussion --

&&

.MARINE...
Issued at 251 PM EDT Thu May 30 2024

High pressure over the Great Lakes is resulting in wave heights
generally a foot or less. The pressure gradient will remain weak
through much of the weekend resulting in low wind and wave heights.
Monday looks like the next time frame where wind and waves may
become hazardous to small craft.

&&

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

&&

$$

DISCUSSION...
AVIATION...Thielke
MARINE...