000
FXUS63 KGRR 190738
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
338 AM EDT Tue Mar 19 2024

.KEY MESSAGES...

- Small chances of snow North today and Wednesday

- Medium to High Confidence for Snow/Mix Late Week

- Low Confidence on Storminess early Next Week

&&

.DISCUSSION...
Issued at 338 AM EDT Tue Mar 19 2024

- Small chances of snow North today and Wednesday

The couple of chances of snow up North that we will see today, and
then again Wednesday, will be associated with a couple of different
short waves brushing the area. The circumstances will be far from
ideal with each of the waves to bring much more than a couple of
tenths of an inch across the North.

The first wave approaching the area today is coming in from the WNW.
The first thing going against much precipitation from this wave is
it is expected to shear out as it drops through the area today. In
addition, deep moisture is never really in place. We initially had
some low level moisture that is making its way out currently. By the
time the mid/upper level moisture lowers enough, there is no low
level moisture to help it reach the ground. The best chance where
these layers of moisture will overlap enough to get some snow at the
sfc will be across the U.S.-10 corridor this morning.

The snow chances then end this afternoon as the wave and moisture
moves by, leaving some short wave ridging in place. Then later
tonight into Wednesday, we will see the next short wave approach the
area from the NW. This wave will remain intact and even strengthen a
bit as it approaches. The problem with this wave for precipitation
chances is that the track of it just barely brushes our northern
counties again. Moisture is once again limited for most of the area,
with just a thin layer up around 4-5k ft, and no real depth in our
area.

- Medium to High Confidence for Snow/Mix Late Week

Upper troughing will extend south into the Great Lakes from the
polar vortex across Hudson Bay by Thursday. An area of snow blossoms
in a baroclinic zone across the NW CONUS/SW Canada on Wednesday and
moves southeast along the arctic front, arriving in Lower Michigan
by late Thursday night into Friday. Models are converging on the
evolution of a sfc wave forming along the front, leading to higher
confidence in the chances for some measurable snow. The surface low
is progged to shear out and weaken, becoming an open wave by Friday
with snow and mixed precip diminishing, but it appears that the
timing of the snow will impact travel for the morning commute.

- Low Confidence on Storminess early Next Week

Western CONUS troughing amplifies and goes negative tilt early next
week and a surface cyclone will evolve over the Plains. Ensemble
spread is significant on the details of how this evolves. The
current forecast is most reflective of the GFS with a less highly
amplified solution and snow arriving on Sunday, changing to rain on
Monday. The more amplified, blocky solutions of the ECMWF and GEM
would hold off precip until Monday or Tuesday.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 147 AM EDT Tue Mar 19 2024

VFR conditions will continue through Wednesday evening. Stratus
deck will prevail with bases around 3500 to 5000 feet AGL this
morning. West winds will gust over 20 kts this morning then go
northwest in the afternoon.

&&

.MARINE...
Issued at 338 AM EDT Tue Mar 19 2024

We will be holding on to the Small Craft Advisory, and extending it
yet again through Wednesday night.

We did give some consideration to upgrading to a Gale for today, but
ultimately decided that the it is a marginal situation for too short
of a duration.

Winds will diminish slightly tonight as one core of wind moves out,
and then another will move in on Wednesday. We could be flirting
with Gales once again, but the situation looks even less favorable
than the marginal scenario today. Winds will finally diminish
Wednesday night, with waves falling below criteria by Thursday at
12z.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 8 AM EDT Thursday for LMZ844>849.

&&

$$

DISCUSSION...NJJ/Ostuno
AVIATION...Ostuno
MARINE...NJJ

NWS GRR Office Area Forecast Discussion