362
FXUS63 KGRR 220752
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
352 AM EDT Wed May 22 2024

.KEY MESSAGES...

- Quiet through Thursday

- Cold Front Brings Showers/Storms Friday night into Saturday

- Low Moves in From the South WIth Rain Showers on Sunday

- Upper Trough Results in Showers Monday into Tuesday

&&

.DISCUSSION...
Issued at 352 AM EDT Wed May 22 2024

- Quiet through Thursday

A cold frontal boundary will move through lower Michigan this
morning as the upper low progresses further north into Ontario. Some
light shower activity will be possible this morning, but most areas
should stay dry. Temperatures drop closer to normal with highs in
the 70s this afternoon and Thursday. Humidity values decrease as
dewpoints fall into the 50s behind the cold front.

- Cold Front Brings Showers/Storms Friday night into Saturday

A cold front will move into the state from the west Friday night
with an increase in moisture and instability. Surface dew points
will push into the 60s with MUCAPE values approaching 1000 j/kg. We
are currently carrying 60-70 pct chances for precipitation as the
cold front sweeps through. Chances will begin late Friday afternoon
and linger into Saturday morning, but the bulk of the rain will fall
Friday night. Rainfall totals will likely be in the quarter to half
inch range in most areas. SPC currently has a marginal in the
southwest cwa. Any severe threat would likely be confined to the
afternoon and evening as stronger storms advect in from the west.

- Low Moves in From the South With Rain Showers on Sunday

A surface low moves in on Sunday from the south bringing chances
for mainly rain showers. We currently have 30-50 percent chances
for rain Sunday into Sunday night as an upper system moves in as
well. The low will be deepening as it moves in with plenty of
moisture to work wit. Can see needing to up chances for rain
Sunday into Sunday night.

- Upper Trough Results in Showers Monday into Tuesday

The upper trough and low linger into the early portion of next
week. We actually have chances for rain from Monday night right
through Wednesday. Can see needing to up our chances from the
current 30-50 percent values with time as well. Also, we may need
to lower temps as there will likely be clouds and showers around
each day.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 200 AM EDT Wed May 22 2024

A cold front is situated north to south over portions of Central
Wisconsin. Ahead of the front a decaying line of showers and
storms are occurring. At this point we have left all thunder
chances out of the TAFs as it looks like the front will come in
largely if not completely dry. Behind the front over Western
Wisconsin, MVFR ceilings are in place. The front and the lower
ceilings will progress into Western Lower Michigan around 12Z.
Lower ceilings (MVFR) will spill into the TAF sites during the
course of the morning. MKG will be most impacted by these ceilings
as they will stay in the bulk of the day. By mid afternoon, most
places should be back to VFR. It looks like the frontal boundary
will pass through the area dry so we are expecting no restrictions
to visibility through the TAF period. South to southwest winds of
15 to 25 knots can be expected the remainder of the night and
through the daytime hours of Wednesday.

&&

.MARINE...
Issued at 352 AM EDT Wed May 22 2024

Strong southwest flow lasts through this morning leading to
hazardous winds and waves. Gusts to 25 to 30 knots are expected
through this morning before winds weaken during the afternoon.
Waves will peak at 7 to 8 feet and will drop from south to north
late morning and afternoon. Conditions will remain hazardous to
small craft through this evening, with conditions improving from
south to north. Marine conditions remain quiet through Friday
before waves begin to build to 3 to 4 feet Saturday morning with
westerly winds.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LMZ844>849.

&&

$$

DISCUSSION...Duke/Thielke
AVIATION...Duke
MARINE...Thielke