Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 242029

Area Forecast Discussion
National Weather Service Grand Rapids MI
329 PM EST Tue Jan 24 2017

Synopsis/Short Term/Long Term/Marine

Issued at 329 PM EST Tue Jan 24 2017

Rain showers will return around midnight tonight across Southern
Lower Michigan, but as the precipitation reaches Central Lower, it
will be a wet snow that will continue into Wednesday morning.  Areas
north of a Whitehall to Mt. Pleasant line could pick up an inch or
two by mid Wednesday, before the snow switches over to a rain and
snow mix Wednesday afternoon.

As colder air arrives Wednesday night, all areas across Central and
Southern Lower will switch over to snow.  However snowfall is
expected to rather light.  Another two inches or less will occur
from Wednesday night through Thursday night across the region.

Periods of lake effect snows will begin to kick in late Thursday
night and last through Sunday.

After highs around 40 both Wednesday and Thursday, we will see
cooler days into the weekend and early next week, with upper 20s to
mid 30s more common.


.SHORT TERM...(This evening through Thursday night)
Issued at 329 PM EST Tue Jan 24 2017

Will not be issuing any headlines just yet.  The window for steady
accumulating snow across Central Lower seems too small late tonight
into Wednesday morning.  Lake effect snows begin to contribute
Thursday night.

Pcpn will be slow to develop tonight due to the lack of deep
moisture.  This will mainly be true due to the surface ridge that
will be hanging on, while the surface storm center only moves to SE
IA by 12Z Wed.  Expect we will see warm advection pcpn break out
between 06Z and 12Z over the NW CWA.  This should be snow, but may
mix with rain at times.

Into Wed morning a burst of steadier snow may occur over the NW CWA,
roughly NW of a MKG-CAD line.  This seems to be the best time frame
for accumulating snows of perhaps an inch or two.  Some minor
impacts are possible, but with temps in the low to mid 30s, main
roads should largely be wet or slushy.  Temps creep up into the mid
and upper 30s by afternoon when more rain will mix in with the snow.
Southern Lower will see all rain Wed.

Similar track of the surface low is expected, roughly from MKG to
Saginaw Bay Wed evening.  But because this is about six hours
slowly, the transition to snow across Southern Lower looks a bit
delayed, mostly occurring after midnight.  Another inch or two will
be possible across Central Lower, but accums will be minimal

It will continue to snow lightly Thursday and Thursday night, with
upper troughing overhead.  But a short wave will approach late
Thursday night.  Its this feature that will usher in the colder air.
Cold enough to kick up the lake effect.  So expecting an uptick to
the snow late Thursday night.  Otherwise the Thursday/Thursday night
snows will generally be an inch or less.

.LONG TERM...(Friday through Tuesday)
Issued at 329 PM EST Tue Jan 24 2017

Made some changes to Superblend in the extended. Bumped up POPs
significantly for Friday through Sunday for lake effect snow and
lowered temperatures a degree or two.

West to northwest flow lake effect snow showers will be enhanced by
a couple shortwave troughs moving through. The first one comes
through Friday morning with inversion heights increasing to near 10
kft. Snow showers should decrease by Friday night then pick up again
on Saturday with the passage of another trough which features a Lake
Superior connection and strong sfc convergence across the SW zones.
We could see a persistent band forming along the I-94 corridor
Saturday night into Sunday.

Lake effect snow should decrease by Sunday night Monday as shortwave
ridging moves in ahead of a clipper and arctic front that arrives
late on Tuesday with synoptic snows being fairly light as the sfc
low passes well to the north. Southwest flow lake enhancement is
possible though.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 105 PM EST Tue Jan 24 2017

IFR conditions should prevail much of the time with rain and snow
at times this evening then steadier rain Wednesday morning. Winds
will be northwest this afternoon then go southeast overnight at or
below 10 knots.


Issued at 329 PM EST Tue Jan 24 2017

A slower than expected movement of the storm system for
Wednesday/Wednesday night will also delay the higher winds.  So at
this point, it does not appear we will need a small craft advisory
until Wednesday night.  However once the rougher conditions arrive,
they should linger through Thursday night.


Issued at 1151 AM EST Tue Jan 24 2017

The area saw anywhere from no rain for the lakeshore counties, to
a third of an inch for some locales along the U.S.-127 corridor
last night through this morning. This is forecast to bring stable
river levels or even some minor rises in the next day or two.
Additional pcpn coming late tonight through Wed will bring between
0.10 to 0.50 inches, highest amounts to the NW. The highest
amounts will be locations that did not see much, so no significant
impacts on the rivers are expected. Also, with some/most of the
pcpn up north coming as snow, this will not run off into the

Cooler air moving in later this week will limit run off also, as
pcpn will fall mostly as snow and little will melt.




LONG TERM...Ostuno
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