039
FXUS63 KGRR 160727
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
327 AM EDT Thu May 16 2024

.KEY MESSAGES...

- Showers and storms late today and tonight

- Dry and very mild weekend

- Chance of showers/storms Monday through Tuesday night

&&

.DISCUSSION...
Issued at 327 AM EDT Thu May 16 2024

- Showers and storms late today and tonight

Mild weather is forecast today with partial sunshine and as winds
become south to southwesterly out ahead of the system approaching
from the west. High temps will reach the low to mid 70s (except
cooler near the Lake MI shoreline). Clouds will gradually
increase through the day but most of the day will be dry. Some
showers and thunderstorms will begin to develop by late this
afternoon as MUCape values reach 500-750 j/kg over our sw fcst
area by then.

A consensus of 00Z HREF svr wx parameters suggests that marginally
severe convection late this aftn/eve will stay to our west across
southern WI. That is where there is potential for stronger
instability to develop along with favorable 0-6km shear on the
order of 30-40 kts and forcing from the front.

We expect weakening convection to gradually move in ahead of the
low pressure system and upper disturbance this evening due to
relatively weak instability over our area. A few showers and
storms will linger Friday with a weak frontal boundary still in
our area.

- Dry and very mild weekend

Upper riding will build into the Great Lakes this weekend and
temperatures will respond by climbing well above normal. Highs are
going to be in the 80s Saturday and Sunday along with quite a bit of
sunshine.

- Chance of showers/storms Monday through Tuesday night

We`re still keeping an eye on a potential stormy pattern Monday
afternoon through Tuesday night. The models are quite a bit more
frisky in regard to generating instability through that period than
last night`s runs.

A northern stream low will push a cold front toward the region
Monday and bring in a strong stream of moisture with it. A minor
short wave looks to accompany the front as it moves toward Lake MI
Monday afternoon. MUCAPE rises to 1200 j/kg near the front and
showers and storms will probably develop along the boundary and clip
at least the western cwa Monday afternoon/night.

GFS and Euro show a second wave developing on the front and moving
northeastward toward Lower MI Tuesday. A stronger short wave
rotating around the low will be a catalyst for convective
development Tuesday afternoon to the west that may move across the
cwa Tuesday afternoon/evening. The LLJ looks to be stronger as does
the instability and especially the shear; we could be looking at
strong/severe storms late Tuesday.

Temperatures will cool off a bit behind the cold front
Wednesday/Thursday.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 121 AM EDT Thu May 16 2024

Latest IR loop shows cirrus moving in from the west. Clouds will
thicken during the day and lower...but still remain VFR through
the period...as a cold front advances eastward. Models continue to
show a chance of showers/storms after 00z and we included that in
the TAFs. It`s possible that cigs will drop below VFR as we get
closer to 06z.

&&

.MARINE...
Issued at 327 AM EDT Thu May 16 2024

Winds will gradually veer to the south and then to the southwest
to west this afternoon. Wind speeds will be fairly light at only
around 10-15 kts. Wind speeds will remain fairly minimal through
late week and this weekend and there really are no concerns for
hazardous winds/waves through then.

&&

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

&&

$$

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