Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 162017
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
317 PM EST Tue Jan 16 2018

LATEST UPDATE...
Synopsis/Short Term/Long Term

.SYNOPSIS...
Issued at 318 PM EST Tue Jan 16 2018

The latest outbreak of cold and snowy weather will come to an end
Wednesday as a warm front pushes through the area thanks to a
storm tracking east in central Canada. Then a rather large Pacific
storm, will move into the western United States later tomorrow and
that will slowly track across the western and central United
States into the weekend. That will keep Southwest Michigan in
seasonably mild January temperatures with little threat for
precipitation. Finally late in the weekend or early next week a
storm from the southern plains, that came from that aforementioned
Pacific storm will bring a fair amount of wind, rain and warmer
temperatures in the Monday time frame. The cold air and snow
return beyond that.


&&

.SHORT TERM...(This evening through Thursday night)
Issued at 318 PM EST Tue Jan 16 2018

The primary issue with this forecast is when does the lake
enhanced snowfall end? Beyond that there will be a slow warm up
but tempeatures are not expected to get above freezing till
Friday.

As far as the lake enhanced snow showers are concerned, as long as
we remain in the upper trough, the snow showers will continue. The
upper trough and the assoicated polar jet that marks the back
edge of the cold air aloft, comes though this area around sunrise
Wednesday. So, I expect the snow showers will continue overnight.
Actually though the snow showers that are going on over central
Lower Michigan should come to a end. What I am watching is the
lake enhanced snow band over western and central Lake Michigan
currently. That will come on shore this evening and move across
the CWA early to mid morning Wednesday. Only the lake shore should
see any measurable snow from that feature and even then it should
for the most part be near or less than an inch.

Once the polar jet gets east of hear we will have some shallow
cold air around through Thursday but it will not be deep enough
for precipitation. A system passing north of this area may bring a
touch of freezing rain to the Route 10 area Thursday evening.
Otherwise expect a slow warm up each day for Wednesday and
Thursday.



.LONG TERM...(Friday through Tuesday)
Issued at 318 PM EST Tue Jan 16 2018

We are looking at moderating temperatures for much of the period
into Monday, before we cool off back to average or slightly below
average temperatures. Precipitation chances will be limited
initially, and will peak late Sun into Mon with the transition.

We will be inbetween systems Fri and likely through most of, if not
all of Sat. The nrn branch of the upper jet will be far enough north
of the area that any effects from nrn waves should stay north also.
A nice SW flow in the lower levels will help to facilitate the
advection of warmer air into the area.

Pcpn chances will begin to increase then by Sun for the area. We
will see a strong upper trough/low kick into the Plains, and help to
strengthen a sfc low across the Central Plains. This will tap more
moisture from the Gulf, and develop pcpn as the forcing interacts
with the moisture. We can not rule out a mix of p-types at the onset
as there is a Canadian High to our north trying to bring in
colder/drier air. Any mix in pcpn should be short-lived once the
developing system takes over control.

The best chance of rain will come Sun night into Mon as the warm
sector pushes in, and the low approaches the area. As we get into
the warm sector, 40s look likely, with 50 degrees not out of the
question. Needless to say, this will melt much of the snow in place
with higher dew points expected and rainfall to accompany the warm
air and wind. Lake effect and temperatures closer to average can be
expected to move back in Mon night/Tue.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1209 PM EST Tue Jan 16 2018

A few small bands of light snow remain scattered across the area
early this afternoon. They are shrinking in coverage, but will
take a few more hours before they clear all of the terminals. KMKG
looks to stay out from under those bands, with the eastern and
southern terminals more likely to see them. We believe they will
be mainly MVFR, but a local spot of IFR remains possible.

This will move out, then we will watch the band of lake effect
over Lake Michigan push onshore tonight. The western terminals
will see the biggest impacts from these, as they diminish pushing
inland. MVFR again looks likely with some chances of local IFR
mainly due to vsbys in the snow showers. These should move out by
15-16z everywhere. Winds will become gusty around 14-16z Wed with
gusts up to around 25 knots likely.


&&

.HYDROLOGY...
Issued at 1230 PM EST Tue Jan 16 2018

The ice jam continues along the Muskegon River in Mecosta County.
Latest information from Emergency Management is that little rise has
been noted since impacts from the jam were reported Monday evening.
Little or no additional impacts have been reported. Previously
open waters have since frozen with ice chunks that have built in
on the back side of the jam, but seem to be stable. Given the
little noticeable changes, we could be seeing the peak, but it
does not rule out ice movement and further fluctuation. Residents
should continue to monitor levels and pay close attention to
latest updates that are provided.

Sites elsewhere are showing some affects as a result of river ice,
but seem to be stable. Minor fluctuations have been noted with
overall downward trends on rivers at or near bankfull. Only one
advisory remains in effect, but is likely to be dropped sometime
late this evening or overnight.

Colder temperatures will allow ice to continue to build over the
next couple of days. There is concern in the upcoming weekend and
into early next week as temperatures rise and precipitation
chances increase. We could see a repeat of last week with melting
snow and rainfall. In addition to weakening ice, runoff could
cause rivers to rise and lead to additional ice jams.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...NJJ
AVIATION...NJJ
HYDROLOGY...JAM


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