Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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886
FXUS63 KGRR 190127
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
927 PM EDT Wed Apr 18 2018

LATEST UPDATE...
Update

.SYNOPSIS...
Issued at 310 PM EDT Wed Apr 18 2018

One more round of light snow tonight and we should be in the clear,
at least for a while. Precipitation will transition to light snow
this evening before ending after midnight. Minor accumulations
coupled with temperatures falling into the upper 20s could make for
slick driving conditions Thursday morning. A warmup begins Thursday
that will carry us through the weekend. Temperatures could reach 60
Sunday and Monday.

&&

.UPDATE...
Issued at 924 PM EDT Wed Apr 18 2018

The band of snow from near Muskegon to Freemont is forecasted by
the high res models to shift southeast through the evening. It
still looks like most locations will end up with less than an inch
of snow. After the snow moves out...temperatures are expected to
fall a few degrees into the upper 20s to low 30s. Thus a risk for
icy roads to start the day exists. Will maintain the current set
of headlines with the evening update.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 310 PM EDT Wed Apr 18 2018

Forecast concerns deal with the potential for another snow event
tonight.

Short range models have been tracking low pressure across IL/IN
tonight. The precipitation shield is much farther north and linked
with the upper low. The cloud shield is now moving across the the
southwest cwa and will cover the cwa tonight. Light rain will
develop this evening and transition to snow by late evening. We`re
not going to see much snow out of this...around and inch and most
likely less. However, the potential exists for the clouds to
dissipate late tonight which will result in temperatures dropping to
the upper 20s. The combination of subfreezing temperatures and not
strong winds should result in slick roads late tonight. We issued a
winter weather advisory to address the threat for icy roads tomorrow
morning.

Precipitation should be over by 12z and skies will clear leading to
warmer temperatures. The warming trend will continue along with dry
weather through the rest of the short term.

.LONG TERM...(Saturday through Wednesday)
Issued at 310 PM EDT Wed Apr 18 2018

Fair weather will dominate the extended period as the Great Lakes
region is under shortwave ridging sandwiched between northern and a
southern stream lows. Eventually, the two lows will merge as
amplification of the northern stream occurs early next week,
bringing a chance for showers by late Tuesday into Wednesday.

Superblend temperatures during this time are warm enough for the
precip to be liquid but some ensemble members of the ECMWF show a
very sharp northern stream trough and temps nominally cold enough
for some snow to mix in. We will not make any changes to Superblend
here and wait for future model trends with this trough.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 720 PM EDT Wed Apr 18 2018

Rain...sleet and snow has been occurring in the area over the past
2 hours. This has resulted in some MVFR and local IFR conditions.
As the precipitation picks up in intensity...a transition to all
snow is expected. It appears there will be a burst of snow this
evening with a risk for IFR and lower conditions. From about
midnight on...the precipitation is forecasted to taper off from NW
to SE through the area. VFR weather is expected for Thursday.


&&

.MARINE...
Issued at 310 PM EDT Wed Apr 18 2018

North winds will pick up tonight as low pressure moves across the
Ohio Valley. The small craft advisory remains in effect tonight
through Thursday night for winds to 30 knots and high waves.


&&

.HYDROLOGY...
Issued at 140 PM EDT Wed Apr 18 2018

Lowland flooding near riverbanks will be ongoing over the next
several days as water from last weekend`s mixed precipitation event
moves through the river basins. About 0.2 inches of rain/snow are
expected tonight in the Grand and Kalamazoo basins. Since no heavy
rain events are anticipated through early next week, river levels
will gradually crest then subside. The exception may be the Muskegon
and Chippewa Rivers, which still have a fair amount of surface water
locked up as snow/sleet. That snowpack will gradually melt with
warmer temperatures this weekend, so flood concerns are limited
though river levels will remain elevated.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 8 AM EDT Thursday for MIZ056>059-
     064>067-071>074.

LM...Small Craft Advisory until midnight EDT Thursday night for
     LMZ844>849.

&&

$$

UPDATE...MJS
SYNOPSIS...04
SHORT TERM...04
LONG TERM...Ostuno
AVIATION...MJS
HYDROLOGY...CAS
MARINE...04



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