Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 181156
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
656 AM EST Mon Dec 18 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 AM EST Mon Dec 18 2017

Areas of light freezing rain or drizzle will make for slick travel
this morning north of I-96. Otherwise a mild week is ahead which
will melt much of our snowpack. However cold arctic air and snow
showers will return around Christmas.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 330 AM EST Mon Dec 18 2017

Have issued a Winter Weather Advisory for ocnl light freezing
rain and drizzle for much of the area north of I-96 through 11 AM.

Sub freezing sfc and road temps are currently present across the
advisory area and model consensus is for between 0.05 and 0.10
qpf between now and 18Z. Sfc temps are progged to slowly recover
above freezing from south to north through the morning, but latest
lamp guidance at Big rapids and Mt Pleasant indicates temps
remaining below freezing through 15Z.

Recent radar has shown an increase in echoes in corridor from MKG
to MOP as well as upstream over srn WI. P-type is tricky with
fcst soundings and hi res guidance pointing toward more snow than
ZR near U.S. 10 and mostly ZR/ZL elsewhere. Moisture depth and
whether or not the DGZ is saturated is also a concern and supports
more in the way of FZDZ.

The weak shortwave providing the lift for the light wintry mix
early this morning exits to the east by afternoon, but cloudy
skies and possibly some patchy drizzle expected to linger. Temps
will probably hold in the mid to upper 30s this afternoon due to
the cloud cover.

Rest of short term period relatively uneventful/mild with main
issue being cloud and temp trends as well as fog potential due to
melting snow/moist boundary layer. Our going sky fcst beyond
today could be too optimistic given potential for stratus.


.LONG TERM...(Wednesday night through Sunday)
Issued at 330 AM EST Mon Dec 18 2017

A high pressure ridge will continue to bring fair wx into Wednesday
night. On Thursday the wx pattern will begin to become more
unsettled as light snow and potentially some mixed pcpn develop in
an area of isentropic upglide mainly over our northern fcst area.

The low pressure system approaching from the west will bring a
better chance of pcpn area wide late Thursday night and Friday.
Thermal profiles should moderate sufficiently enough across (at
least) the southern half of our fcst area for rain Friday. A
wintry mix of pcpn is possible across our northern counties. We
will need to monitor this system closely as some of the medium
range guidance including the 00z ECMWF has now trended cooler as
compared to previous runs.

A cold airmass will begin to advect in behind that system Friday
night and through the weekend. A consensus of latest medium range
guidance continues to indicate potential for an even colder
arctic airmass to move in next week. However a trend is noted in
some of the medium range models including the ecmwf to delay the
arrival of the coldest air until late in the week.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 655 AM EST Mon Dec 18 2017

Widespread IFR or lower conditions will be present this morning
due to low stratus, drizzle and fog. Some improvement in
cigs/vsbys is expected this afternoon as light rain/drizzle ends,
although cigs probably remaining in IFR category. For tonight the
winds will increase out of the southwest to 12-20 kts and cigs
should lift into MVFR or better category.

&&

.MARINE...
Issued at 330 AM EST Mon Dec 18 2017

No changes made to the small craft advisory as winds increase out
of the southwest later today and tonight.

&&

.HYDROLOGY...
Issued at 323 PM EST Sun Dec 17 2017

A few gauge sites remain ice affected, most notably the Looking
Glass at Eagle and the White River at Whitehall. Of the two, Eagle
is the only site with a level confirmed to be above bankfull.

All sites are stable at this point and the Looking Glass River
continues to recede. Improvement is expected to continue with warmer
temperatures over the course of the work week. Precipitation is also
manageable with only a few tenths of an inch forecast through the
next 7 days.

Flood risks are minimal. For now, concerns are largely focused on
behavior existing ice jams. Otherwise, no addition flooding is
expected at this time.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 11 AM EST this morning for
     MIZ037>040-043>046-051-052.

LM...Small Craft Advisory from 2 PM this afternoon to 7 PM EST
     Tuesday for LMZ844>849.

&&

$$

SYNOPSIS...Meade
SHORT TERM...Meade
LONG TERM...Laurens
AVIATION...Meade
HYDROLOGY...JAM
MARINE...Meade



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