000
FXUS63 KGRR 211225
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
725 AM EST Thu Jan 21 2021

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 328 AM EST Thu Jan 21 2021

- Breezy and milder today

- Cold Friday with light lake effect snow showers

- Snow possible Sunday and Monday

&&

.DISCUSSION...(Today through Wednesday)
Issued at 328 AM EST Thu Jan 21 2021

-- Breezy and milder today --

It will be breezy and milder today as strong southwest
to wsw flow waa will help to boost high temps into the
middle to perhaps upper 30s. A cold front will bring a
few light snow showers and flurries late tonight.

-- Cold Friday with light lake effect snow showers --

Nw flow light lake effect snow showers are forecast Friday
as h8 temps will fall to -16 to -18 C yielding high delta t/s.
However les potential has significant mitigating factors
including lack of deep moisture and low inversion heights of
around 5 kft agl. Therefore only light snow accumulations
on the order of an inch or two are expected in our favored
nw flow snow belt regions.

-- Snow possible Sunday and Monday --

The deterministic 00z ecmwf shows potential for a little
light snow to move in from the west Sunday.  Then for Monday
a consensus of medium range guidance the past several days
has shown potential for a fairly strong low pressure system
to move across the lower Ohio Valley region Monday with heaviest
pcpn with that system staying south of our area.

However ECMWF guidance and ensembles have trended further north
and now show potential for snow with potentially significant
accumulations across much of our area with potential for at
least a half to three quarters of an inch of qpf. There is still
considerable uncertainty in terms of exact track and strength of
the system though. It is noted that the 00Z GFS is significantly
further south.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 724 AM EST Thu Jan 21 2021

VFR conditions will continue into the afternoon then MVFR will
prevail from late afternoon through tonight. West winds will
increase to near 20 knots with gusts to 30 knots this morning
turning northwest in the afternoon.

&&

.MARINE...
Issued at 328 AM EST Thu Jan 21 2021

It will be breezy today and remain breezy tonight and Friday as a
significantly colder airmass moves in. Therefore a small craft advisory
is in effect through late Friday evening. It will take until the
early morning hours Saturday for waves to subside to below sca
criteria.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 3 AM EST Saturday for LMZ844>849.

&&

$$

SYNOPSIS...Laurens
DISCUSSION...Laurens
AVIATION...Ostuno
MARINE...Laurens

NWS GRR Office Area Forecast Discussion