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610
FXUS63 KGRR 250742
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
342 AM EDT Sat May 25 2024

.KEY MESSAGES...

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- Potential for Storms Sunday Evening

- Cooler and Showery for Memorial Day and Tuesday

- Dry Weather for Wednesday through Friday
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&&

.DISCUSSION...
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Issued at 342 AM EDT Sat May 25 2024

- Potential for Storms Sunday Evening

Surface ridging moves in behind last nights cold front leading to
quiet weather today. Focus turns to Sunday evening into Monday for
more active weather potential.

An mid-level trough rooted over the Central Plains ushers in a
staunch shortwave through the Great Lakes as an associated surface
low ejects out of the Rockies and occludes while moving into Lower
Michigan. As a warm front lifts northwards, convection will develop
before a cold front sweeps through later in the evening and
overnight.

Instability is still pretty lacking across southern Michigan, but
there is uncertainty on the track of the low. Deterministic NAM
and GFS bring the low through central lower Michigan while the
Euro is taking a more northerly route bringing the low toward the
tip of the mit. A more northerly track of the low would put
southern Michigan more into the warm sector and supporting more
severe weather development, while a more southerly track would
keep favorable conditions for severe storms to our south. Even
with the Euro advertising a more northerly track instability is
still limited for our area. Altogether it appears the trends are
favoring keeping the better instability south of the state line
which reflects well with the SPC Day 2 outlook with Marginal up
towards I-96 and Slight just south of the state line. A few strong
storms may creep up towards I-94 to I- 96, but generally expect
most of the severe weather activity to keep to our south.

Still quite a bit of disagreement on rainfall totals through
Monday morning with ensemble 24 hour QPF ranging from a few
hundredths to over 1 inch across the I-94 corridor. PWAT values
nose up towards 1.5 inches Sunday afternoon, so locally heavy rain
will be possible with thunderstorms.

- Cooler and Showery for Memorial Day and Tuesday

Cooler air will filter into the Great Lakes for Memorial Day and
Tuesday as the low moves northeast into Ontario allowing a cold
front to press off to the east early in the day. 850mb temperatures
drop back into the single digits for early to mid week which should
mean highs in the 60s. Showery weather can be expected as multiple
shortwaves rotate through an upper trough which will be situated
above the Great Lakes. Overall rainfall is expected to be on the
lighter side given the deeper moisture will push off to the south
and east with the cold front early Monday. Rainfall amounts will
likely be less than a quarter of an inch for the Monday/Tuesday time
frame. Some local pockets of a quarter to a half inch will be
possible. Highs will be in the 60s given the cooler temperatures
aloft and clouds/showers. It will not be a rainout by any means, but
we will see some occasional light rain/showers.

- Dry Weather for Wednesday through Friday

Dry weather is a high confidence forecast for Thursday and Friday
with both ridging at the surface and aloft. Wednesday there could be
a few lingering showers, especially diurnally in the heat of the
day. 850mb temperatures will dip to +3 to +4 C Wednesday morning.
The cold air aloft and strong heating from a late May sun angle will
likely bubble up some scattered showers in the midday and afternoon
hours. Highs will likely hold in the 60s on Wednesday, rising into
the 70s for Thursday and Friday.
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&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 204 AM EDT Sat May 25 2024

A cold front stretches north to south over portions of eastern
Wisconsin down into Illinois at 200am. A band of MVFR/IFR ceilings
is located over Eastern Wisconsin and Northeast Illinois near and
just ahead of the front. It appears that the shower and
thunderstorm threat is largely over and the main issue in the TAFs
will be a period of IFR/MVFR conditions as the front moves
through. The ceilings will progress through the TAF sites from
west to east between 400am and noon. We cannot rule out an
isolated/scattered shower ahead of the front, so we have VCSH
wording in the TAFs. VFR weather is expected after noon.

&&

.MARINE...
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Issued at 342 AM EDT Sat May 25 2024

Conditons stay quiet through today, then westerly winds build Sunday
night with an advancing low pressure system. Showers and storms will
be possible Sunday afternoon, and winds and waves will build
through Monday. Conditons will be dangerous for small craft, and
waves and rip currents will be dangerous for beachgoers Sunday
night through Monday evening.
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&&

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

&&

$$

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