-- Discussion containing changed information from previous version are highlighted. --
140
FXUS63 KGRR 111045
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
645 AM EDT Tue Jun 11 2024

.KEY MESSAGES...

- Small rain chances tonight

- Chance of storms Wednesday night, chance of strong storms Thursday

- Hot late weekend, early next week

&&

.DISCUSSION...
Issued at 328 AM EDT Tue Jun 11 2024

- Small rain chances tonight

High pressure building both aloft and at the sfc this morning is
allowing for clear skies across the area. You can see how the upper
ridge axis to our west and confluent flow aloft is helping to
dissipate the high clouds trying to move in. We will see high
temperatures a few degrees warmer as the temperatures at 850 mb will
warm 2-3C since 24 hours ago.

We will see a weak short wave and sfc warm front approach the area
this evening, and pass to our east overnight. We expect a lot of mid
level clouds with this as a weakening low level jet will nose in
overnight. There will be lots of virga with dry low levels hanging
on. A few light showers will reach the ground at a few pockets
where the showers are a bit heavier, with light amounts expected.

Once the front moves through prior to daybreak on Wednesday, we will
see any light rain showers and the clouds clear out. In addition, we
will see 850 mb temperatures warm another 5-6C. This will make a
difference in temperatures, going from mid 70s today, to low to mid
80s on Wednesday.

- Chance of storms Wednesday night, chance of strong storms Thursday

There is a chance of showers/storms across the northern half of the
cwa Wednesday night as a short wave moves across the state. PWATs
rise to over 1.5 inches, so showers/storms that develop could
briefing put down some heavier rain.

The bigger threat for storms will arrive Thursday as a weak cold
front pushes into the region. Timeframe for strong storms looks to
be from 16z-00z. SBCAPE around 1500 j/kg coupled with a spike in mid
level lapse rates close to 7c/km and the right entrance region of
the upper jet should provide enough dynamics for a few storms to be
strong to severe. Bulk shear near 40kts increases the chances for
cell organization. PWATs near 1.7 inches suggests a heavy rain
threat too. We`ll continue to monitor the situation.

- Hot late weekend, early next week

An upper ridge will begin to move from the Plains to the Great Lakes
and as heights rise, so will surface temperatures. H8 temperatures
rise from 8c Saturday to 18c Sunday and 20c Monday. Surface
temperatures are progd to rise from 80 Saturday to 90 Sunday and mid
90s Monday. Additionally, dewpoints in the 50s Saturday will climb
to the lower 60s Sunday, upper 60s Monday and around 70 Tuesday.
Heat indices will close in on 100 Monday; summer is definitely here.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
-- Changed Discussion --
Issued at 644 AM EDT Tue Jun 11 2024

No changes to the forecast. Mostly clear skies today will give way
to a mid cloud deck around 10k feet tonight as an upper trough
moves through.
-- End Changed Discussion --

&&

.MARINE...
Issued at 328 AM EDT Tue Jun 11 2024

It is likely we will not need any headlines until we approach the
late Wednesday night/Thursday time frame. A very weak gradient is in
place today with high pressure dominating the weather today. Winds
will increase some tonight with a weak low level jet passing
overhead. The winds aloft will not be favorable for making it to the
ground with warmer air nosing in and a stable lower atmosphere.

We will see winds increase sufficiently with a better gradient with
a weak cold front moving through on Thursday. It is then that it
looks more likely to need some Small Craft and Beach Hazards
headlines.

&&
06
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.

&&

$$

DISCUSSION...NJJ
AVIATION...04
MARINE...NJJ