Meridian, Michigan 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

408
FXUS63 KGRR 240830
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
330 AM EST Sun Nov 24 2024

.KEY MESSAGES...

- Rain showers tonight into Tuesday morning

- Light snow chances later Wednesday through Thanksgiving Day

- Pattern change to colder air and lake effect late in the week

&&

.DISCUSSION...
Issued at 330 AM EST Sun Nov 24 2024

- Rain showers tonight into Tuesday morning

The clouds that have been plentiful over the area the last couple of
days continue to hold on strong this morning. We have a layer of
both lower clouds and high clouds. We can not rule out seeing some
breaks in the cloud cover and some filtered sunshine this afternoon
as the low clouds dissipate and high clouds remain while ridging
aloft and at the sfc builds toward the area into this afternoon.

The break will be short lived however as our next system will be
organizing to our west this afternoon, and moving in tonight. There
is an upper wave over Southern ID this morning that will move out
into the Upper Midwest, and support a sfc low moving from the Front
Range of the Rockies, to near Chicago by 12z Monday morning. The
upper wave will be strengthening as it phases with a northern stream
wave across Southern Canada.

Initially there will be no precipitation with the sfc low due to a
lack of moisture. A 30+ knot low level jet nosing up into the area
later tonight will supply sufficient moisture for showers to
eventually develop later on. We will likely see a break between the
showers later tonight ahead of the front, and the next round of
showers that will come in that will be associated with the upper
wave Monday afternoon and night. The upper trough axis will pass
east of the area by 12z Tuesday, so most of the shower activity
should have ended by then.

- Light snow chances later Wednesday through Thanksgiving Day

The southern portion of our area could see some light precipitation
redevelop as early as Wednesday morning and linger much of the day.
There are not any strong features present at the sfc or short waves
aloft driving these chances. What is there are a couple of jet
streaks working together helping to provide some upper divergence
centered just south of the state. This jet energy, combined with a
low level flow out of the Gulf will help to develop precipitation.

The precipitation could be some light rain or snow depending on when
it falls. If it starts early enough, some light snow would be
possible before the boundary layer can warm up enough to mix some
rain in, or change it over to all rain. This precipitation should
not be significant coming off of ridging and drier weather from
Tuesday. Any rain on Wednesday could change back over to snow
Wednesday night.

We are watching for the potential of some accumulating snow for
Thanksgiving Day, especially for the southern half of the forecast
area south of I-96. The feature responsible for this potential is
the closed low off of the coast of the Pacific NW. This low is going
to be absorbed into the main jet stream, and open up and lift
through the Rockies and Plains toward the Ohio River Valley. This
will be inducing a decent sfc low that looks to track along the Ohio
River Valley also.

There has been some uncertainty as to how much of the precipitation,
in the form of snow will affect our area. The uncertainty really
rests in the evolution of the upper low/wave. A majority of the
ensemble data has been showing most of the snow staying south of the
area, with I-94 getting clipped with an open wave staying south.
There have been some outlier solutions showing the upper low being a
bit more closed, and wrapping more moisture up into the area. We are
currently leaning more toward the open wave and further south snow
solution with better agreement. We are watching for the low
potential of the closed low solution verifying, which would affect
the holiday a bit more.

- Pattern change to colder air and lake effect late in the week

No matter what track the upper low and sfc low takes on Thursday, we
are looking at high confidence of a pattern change that will bring
colder weather to the area, along with potential of a prolonged
period of lake effect for the first couple of columns of counties
near the lakeshore. 850 mb temperatures will be dropping to around
-10 to -12C providing plenty of sufficient instability for lake
effect. The upper flow pattern will be cyclonic with colder air
aloft overhead, leading to higher inversion heights and deeper
instability. The low level flow looks like it will be mainly from
the NW. That will favor the SW and NW corners of the area to see
snow accumulations of at least a few inches. Plenty of details have
to be fine tuned over the next few days.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1241 AM EST Sun Nov 24 2024

MVFR ceilings are prevailing south of MKG/GRR/LAN, and are already
pretty close to IFR in some spots. Consensus of short-term model
guidance is for IFR to become more common in southern Michigan
through about 15Z, and also MVFR to borderline IFR will creep
northward to include MKG/GRR/LAN. After 18Z, clouds at or below
2,000 feet will tend to become more scattered or few, though
areas of MVFR may remain.

&&

.MARINE...
Issued at 330 AM EST Sun Nov 24 2024

Our next marine headline event is expected to come late Monday into
Tuesday behind a frontal system that will be moving through the
area. Winds will come up a bit ahead of the front tonight, but as of
now look to stay just below Small Craft Advisory criteria. Helping
this cause will be an offshore component to the wind that should
keep the strongest winds offshore. A decent surge of colder air
behind the front along with a stronger gradient should bring our
nearshore easily to SCA conditions, with Gales not out of the
question. The threat of Gales at this time looks to be too low for a
watch at this time.

We may get into a prolonged SCA event then late in the week and next
weekend. Onshore flow with colder air funneling in over the area
will help to kick winds and waves up a bit.



&&

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

&&

$$

DISCUSSION...NJJ
AVIATION...CAS
MARINE...NJJ