Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 181910
AFDGRR

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

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

.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.

&&

.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 18Z TAFS through 18Z Thursday afternoon)
Issued at 140 PM EDT Wed Apr 18 2018

VFR conditions this afternoon and evening will transition to MVFR
and IFR as rain moves in by 00Z and transitions to snow later this
evening. The steady snow will taper off around 06Z and some
partial clearing is possible late with VFR conditions expected to
return after 12Z Thursday.

East winds around 10 knots will go northeast this evening then
north on Thursday with some gusts to 20 knots.


&&

.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 from 11 PM this evening to 8 AM EDT
     Thursday for MIZ056>059-064>067-071>074.

LM...Small Craft Advisory from midnight tonight to midnight EDT
     Thursday night for LMZ844>849.

&&

$$

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



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