Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 181447
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1047 AM EDT Sat Mar 18 2017

LATEST UPDATE...
Hydro

.SYNOPSIS...
Issued at 330 AM EDT Sat Mar 18 2017

Light drizzle or light snow will continue much of Saturday, but
little to no accumulation is expected.  High temperatures will be in
the upper 30s to lower 40s.  Sunday will turn out to be a nicer day,
with some sunshine and temperatures in the 40s.  A cold front will
push rain back into the area late Sunday night and it will continue
Monday.  However the rain is expected to end through the afternoon.

The rest of the week appears to be rather quiet, although another
chance of rain should return by Thursday night into Friday.  Most of
the days should see temperatures in the 40s, but a warm up is
expected by late in the week.

&&

.SHORT TERM...(Today through Monday)
Issued at 330 AM EDT Sat Mar 18 2017

An upper low will continue to move across the CWA early this
morning.   This will continue to cause areas of light drizzle or
occasionally snow.  The DGZ is fairly dry through much of the day,
but it appears we will occasionally see cloud tops reach into the
DGZ for some snow mixing in at times.  Any snow accums will be
isolated and only a dusting where a random snow burst occurs.

The drizzle will gradually diminish toward 00Z this evening as the
moisture continues to become more shallow as the upper low moves
away.  The clouds should begin to break up a bit toward daybreak,
otherwise it will just be cloudy much of the night.

Surface high pressure arrives into Sunday.  Looks like we keep
enough low level moisture to expect some clouds through the day.
Will call it partly sunny.  Highs into the low and mid 40s.

Then a cold front arrives by Monday morning.  Moisture appears
rather limited, so expected scattered showers, most common late
Sunday night into Monday morning.  Total pcpn will likely be a tenth
of an inch or less.

.LONG TERM...(Monday night through Friday)
Issued at 330 AM EDT Sat Mar 18 2017

Much of the long term looks dry and cooler than average, with a
trend toward more wet and warmer conditions by next weekend.

We will be in between systems on Monday night, keeping conditions
rather mild and dry. The colder air will arrive later Tuesday as a
secondary and stronger cold front pushes south through the area.
Sufficiently cold air will advect over the area for lake effect to
be possible with H850 temps dropping to around as low as -16 to -17C
by Wednesday. We have kept a dry forecast going as the sfc ridge
builds almost overhead, and the low level flow from the NNE will
likely keep lake effect out of our area.

This ridge will push out of the area by Thu, allowing for return
flow to set up over the area. The flow coming from the south will
eventually advect enough warmth and moisture into the area ahead of
the next system to begin chances of pcpn beginning Thu night and
lasting through Sat. The pcpn will likely start out as some snow
with cold enough temp profiles in place. Any snow will change over
to rain quickly on Fri as much warmer air advects in. We could see a
decent amount of rain with a deep srly flow becoming established
ahead of the long wave trough out west.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 740 AM EDT Sat Mar 18 2017

Much of the region remained under IFR conditions early this
morning. It is expected that this will hold through the rest of
the morning. But as winds pick up, as well as the mixing, more
MVFR will develop into the early afternoon. Then as the winds
diminish again early this evening we should see some IFR
redevelop. This appears most likely for the I-96 TAFs, while the
I-94 TAFs may remain MVFR. Drier air will slowly work in
overnight, which should erode the IFR across I-96 through the
overnight.

Northwest winds will pick up later this morning to 10 to 15 knots,
then diminish again early to mid evening.

&&

.MARINE...
Issued at 330 AM EDT Sat Mar 18 2017

Small craft advisory conditions will continue into today.  Decided
to extend areas south of Grand Haven through the evening hours.
Northwest winds will peak to 25 knots later this morning.  These
winds will turn more to the north this evening and slowly diminish.

&&

.HYDROLOGY...
Issued at 1047 AM EDT Sat Mar 18 2017

River levels are running around normal to a little below normal.
With less than a half inch of precipitation expected through this
weekend and then no additional precipitation until Friday, no
flooding is expected across the area into next weekend. The
precipitation next weekend may be enough to push river levels up,
but they should remain below bank full.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 8 PM EDT this evening for LMZ847>849.

     Small Craft Advisory until midnight EDT tonight for LMZ844>846.

&&

$$

SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...NJJ
AVIATION...JK
HYDROLOGY...63
MARINE...JK



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