817
FXUS63 KGRR 041900
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
300 PM EDT Sat May 4 2024

.KEY MESSAGES...

- A few showers,maybe some thunder this evening, quiet Sunday

- Dry Monday, then chances for showers/storms

&&

.DISCUSSION...
Issued at 255 PM EDT Sat May 4 2024

- A few showers,maybe some thunder this evening, quiet Sunday

Showers/thunderstorms will try to get their act together this
afternoon in Illinois and Wisconsin will move across Lake Michigan
and western Indiana early this evening along with a weak cold front.
Models are indicating this line will struggle to remain organized
as it moves east and considering decreasing elevated instability
overnight - it is looking more like a broken weakening line of
showers/thunderstorms that may result in quite a bit of the area
seeing no rain at all. If any storms do hold together, not out of
the question that some small hail will be possible though this
doesnt look that likely at this time.

Any lingering light showers should be off to the east by daybreak
Sunday. High pressure begins to build in Sunday with stubborn cloud
cover lingering through much of the day. This could result in cooler
temperatures than Saturday but dry weather should result regardless.

- Dry Monday, then chances for showers/storms

Transient high pressure over Lower MI Monday will produce sunny
skies and mild temperatures with highs around 60. An upper low over
the northern Plains will influence our wx the rest of the week as
pieces of energy will rotate through the flow and move across the
region.

Clouds will increase Monday night with storms likely Tuesday when a
warm front lifts north late in the day. Moderately strong dynamics
look to be develop late Tuesday as a LLJ moves over the region and a
mid level speed max aims at Lower MI from the southwest. H85-h5
lapse rates also climb to around 7c/km during this time frame. Given
the warm frontal interaction, strong shear and decent helicity, all
forms of severe wx look to be possible from late Tuesday afternoon
through Tuesday evening; SPC has highlighted the southwest cwa for a
severe wx risk.

Once the warm front moves through late  Tuesday night there may be a
lull in precipitation until the next wave over the central Plains
moves toward the region late Wednesday through Thursday night. More
showers/storms are expected then. The upper low isn`t progd to move
through the state until late Saturday, so unsettle conditions will
continue through the first half of the weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 124 PM EDT Sat May 4 2024

Pesky MVFR cigs continue across some of the terminals. Latest
visible imagery shows some decrease in the cu field which should
lead to a decrease in MVFR cigs this afternoon.

An approaching cold front will fire off a line of showers/storms
over IL late this afternoon which will then move east. However,
it`s going to encounter more atmospheric stability which will
weaken the line. We included a VCSH comment in the TAFs and any
precipitation that does develop should be in weakening mode as it
moves through.

Models indicate more IFR/LIFR tonight along the frontal boundary.
Once the front clears the region Sunday morning, cigs will lift.

&&

.MARINE...
Issued at 300 PM EDT Sat May 4 2024

Winds this evening still expected to nudge up this evening as a cold
front works across Lake Michigan. A few showers and some thunder
possible but showers/storms should be weakening as they approach the
shoreline. Behind the front north/northwest flow should increase a
little but at this time looks like it should peak out 15-20kts and
will continue to hold off on an advisory.

&&

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

&&

$$

DISCUSSION...Maczko/04
AVIATION...04
MARINE...Maczko