Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 181440
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1040 AM EDT Mon Mar 18 2024

.KEY MESSAGES...

- Snow showers to diminish today, snow chances North tonight

- Slight chance snow showers Tuesday night

- Chance of Snow/Mix Late Week

&&

.UPDATE...
Issued at 1040 AM EDT Mon Mar 18 2024

Increased the probability of precipitation through the rest of the
day across much of the area. This is due to a front moving through
helping to provide lift across the area along with the lake effect
along the lakeshore. Front is roughly along a Muskegon to Big
Rapids line and will gradually shift south through the day. An
additional dusting is possible for most, with areas in Allegan,
Van Buren and western portions of Kalamazoo county seeing an
additional half inch to inch and a half. Make sure to take it slow
in the snow!

&&

.DISCUSSION...
Issued at 340 AM EDT Mon Mar 18 2024

- Snow showers to diminish today, snow chances North tonight

As expected, periods of snow showers continue to be concentrated
along the lakeshore with much less coverage inland early this
morning. This is all the result of cold enough air producing
sufficient instability over Lake Michigan, and the main upper trough
axis dropping through the region.

Radar imagery indicates a likely sfc reflection of this trough over
the southern portion of the lakeshore from Holland through South
Haven at 07z. Additional snow showers are ongoing up north, but
radar returns and sfc visibilities are not indicating anything
significant falling. This relative break behind the sfc reflection
is some short wave ridging in the wake of the trough.

Inversion heights up around 8k ft will remain up into this morning
before sinking late this morning and afternoon. This is because the
upper trough and cold pool will be exiting the area. This will help
to diminish the snow shower intensity and coverage. Can not rule out
an inch or two near the lakeshore under the heavier snow showers
through the morning. By afternoon, accumulations will be little to
none as we warm up above freezing and ground sfcs will rise with
solar radiation.

We will see another chance of some light snow tonight. This light
snow will be focused roughly on the NE half of the area. There is
another wave and sfc low that is moving through the Northern Great
Lakes. This setup does not look favorable for much of any snow for
our area. We see mid level moisture move through with limited low
level moisture. Then by the time some low level moisture moves in,
the mid level moisture is gone. Mainly quiet weather is expected by
Tuesday, with temperatures about 10 degrees warmer as we will be in
the warm sector of this system.

- Slight chance snow showers Tuesday night

A clipper tracks southeast out of Canada Tuesday night in fast
northwest flow but the low center remains to our north and moisture
is limited. Model guidance and WPC QPF indicate lake enhanced snow
showers for late Tuesday night into Wednesday morning and slight
chance POPS have been expanded south to cover most of the forecast
area in this northwest flow regime.

- Chance of Snow/Mix Late Week

Complex evolution of the flow regime across the CONUS middle and
late next week with a rex block across the West breaking down and
upper low moving east. Model guidance has largely converged on a
solution showing more troughing/lower heights extending south across
the Great Lakes from a polar vortex across Hudson Bay by Friday with
a baroclinic zone along the US-Canadian border. An area of snow
blossoms in this baroclinic zone across the NW CONUS/SW Canada on
Wednesday and moves southeast along the arctic front, arriving in
Lower Michigan by late Thursday into Friday. This could bring at
least a light accumulation of snow.

Unsettled weather looks to continue into the weekend with an
inverted trough bringing snow and mixed precip on Saturday or Sunday.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 717 AM EDT Mon Mar 18 2024

Snow showers with areas of MVFR conditions and brief IFR across
western Lower Michigan will be tapering off by this evening. VFR
conditions should prevail after about 15Z but northwest winds will
continue to gust over 20 knots at times through the afternoon.

&&

.MARINE...
Issued at 340 AM EDT Mon Mar 18 2024

We have extended the Small Craft Advisory out in time another 24
hours through Tuesday night. Winds will stay up for the most part,
except for some very brief periods. The waves will not have a chance
to drop below the 4 foot criteria until late Wednesday
night/Thursday. High pressure building in on Thursday should allow
winds and waves to drop enough to not need an advisory at that time.

&&

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

&&

$$

UPDATE...RAH
DISCUSSION...Ostuno/NJJ
AVIATION...Ostuno
MARINE...NJJ


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