Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KGRR 121429
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
929 AM EST Fri Jan 12 2018

LATEST UPDATE...
Update

.SYNOPSIS...
Issued at 330 AM EST Fri Jan 12 2018

Arctic air returns to the region today behind a cold front and
will be with us into next week. Some roads will be slick for the
morning commute as temperatures fall into the 20s and residual
moisture freezes up. Also a 1 to 4 inch snowfall is expected this
morning for areas south and east of a line from South Haven to
Alma.

Lake effect snow will occur near Lake Michigan over the weekend
but no significant accumulations are expected. A more widespread
snow is expected beginning Sunday night and continuing through
Tuesday, with some light accumulations likely over most of the
area.

&&

.UPDATE...
Issued at 926 AM EST Fri Jan 12 2018

Increased snow amounts for east and southeast counties as the
banding continues. I did add inch per hour rates to the WSW. High
res models show the snow diminishing later this morning into the
afternoon.  No other changes at this time.


&&

.SHORT TERM...(Today through Sunday)
Issued at 330 AM EST Fri Jan 12 2018

No changes to the existing Winter Weather Advisory. Good lift and
FGEN forcing will be present this morning as upstream mid level
trough deepens and moves east. Also there is plenty of moisture to
work with as precip transitions quickly to snow, with 4-5 g/kg
mixing ratios still noted on the 300K sfc from GRR to the south
and east.

Snow could become briefly heavy at times during the morning commute,
and some localized 4-5 inch total accums cannot be ruled out
within any of the more intense FGEN bands which set up south and
east of GRR. The period of freezing rain and sleet in the
transition zone is expected to be relatively brief this morning
given the fast arrival of the cold air behind the front, and have
raised total snow amounts a bit for the LAN/JXN/BTL areas. This is
supported by latest trends in the HRRR which are farther north
and west with the snow this morning and show the banded nature of
the snow.

Most of the snow should be done by noon, but increasing northerly
winds could lead to some blowing snow lingering into the
afternoon where accums occur.

Things turn relatively quiet but cold after today. The lake
effect snow over the weekend does not look too impressive since
moisture is fairly shallow and inversion heights generally below
5K feet. However there still may be some localized light
accumulations west of Highway 131.

.LONG TERM...(Sunday night through Thursday)
Issued at 330 AM EST Fri Jan 12 2018

A stacked low is progged to be moving into the Western Great Lakes
by early next week.  This will keep the region in the cold air,
along with a prolong period of snow that should start late Sunday
night and last until Monday night or Tuesday.  This system will also
see some lake enhancement with H8 temps around -15C.  This will be
mainly true once the low is to our east, by Monday night.  Snow
amounts could be rather impressive, with 2-4 inches expected inland,
and perhaps 6-9 inches for areas west of U.S. 131 by Tuesday
morning.  Once this system is to our east another reinforcing surge
of arctic air moves in for Tuesday and Wednesday. Lake effect snow,
mainly hugging the coast should persist these two days.

By Wednesday night and Thursday temperatures should not be as cold
as an upper ridge builds over the upper Midwest.  Surface high will
also accompany the ridge, so it appears dry for this period.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 653 AM EST Fri Jan 12 2018

IFR to LIFR conditions expected this morning from GRR to the south
and east due to widespread and occasionally heavy snow. West of
the snow area conditions will be MVFR with just a few flurries at
MKG. Look for improvement to VFR from west to east later this
morning into the afternoon as the snow ends/moves out. North sfc
winds will be gusty at 15 to 25 kts today into the evening, likely
not diminishing until rather late tonight.


&&

.MARINE...
Issued at 330 AM EST Fri Jan 12 2018

Gales and freezing spray expected on Lake Michigan as arctic air
pours in.


&&

.HYDROLOGY...
Issued at 330 PM EST Thu Jan 11 2018

Snowmelt is expected into tonight, as warm moist air continues to
invade the region. Most of the snow pack should melt, but not all of
the melt water will make it into the river system before the cold
air moves back in and locks it down later tonight through the
weekend.

There is still 1 to 2 inches of snow, mainly north of Grand Rapids.
No excessive rainfall is expected with the warmup and amounts should
be generally under one half inch through the warm period. This has
resulted in minor river flooding scattered across Southwest Lower
Michigan. Some ponding of water, away from the rivers, will be
possible. The rivers will need to be closely monitored for ice
breakup and potential ice jam flooding.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 7 PM EST this evening for MIZ059-
     066-067-073-074.

     Winter Weather Advisory until 1 PM EST this afternoon for
     MIZ050>052-056>058-064-065-071-072.

LM...Gale Warning until 4 AM EST Saturday for LMZ844>849.

&&

$$

UPDATE...MJS
SYNOPSIS...Meade
SHORT TERM...Meade
LONG TERM...JK
AVIATION...Meade
HYDROLOGY...63
MARINE...Meade



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.