Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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727
FXUS63 KGRR 242353
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
653 PM EST Fri Feb 24 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 PM EST Fri Feb 24 2017

A quick return to winter arrives overnight and continues into
Saturday.  Rain will change to snow overnight.  Snow accumulations
of 1 to 3 inches can be expected west of U.S. 131 by Saturday
evening.  Along with this will be wind gusts to 35 mph at times.
Farther east snow accumulation will generally be an inch or less.
Another weak system moves across Central Lower on Sunday, but snow
accumulations are only expected to be a dusting there.

Another warmup is expected into next week, with rain moving in
Tuesday and Tuesday night.  Another system could bring a rain and
snow mix for Thursday.

The weekend cool down will bring high temperatures down into the
30s, but then we should warm toward 50 degrees for Monday and
Tuesday.  Cooler weather is expected later in the week with highs
closer to 40 for Wednesday through Friday.

&&

.SHORT TERM...(This evening through Sunday night)
Issued at 330 PM EST Fri Feb 24 2017

Severe weather threat still possible through about 04Z this evening,
then we turn back to a winter regime.

Will go with a winter weather advisory for the lakeshore and Lake
County late tonight through Saturday.  Lake effect snow showers and
deformation zone will develop late tonight.  Expecting 1 to 3 inches
of snow and wind gusts to 35 mph at times.  This will create
hazardous conditions, and after a long break without snowfall we
felt it was best to advise. The steadiest snows will occur
Saturday morning when the wind also peaks, so some brief whiteout
conditions will be possible through the first half of the day.
Farther east most accumus will be an inch or less.

After a quiet Saturday night, a cold front sags in from Northern
lower on Sunday.  Higway 10 should see some light snow, but with
temps in the 30s accums won`t amount to much, under an inch. Farther
south the front will struggle to push snow too far south with high
pressure in the OH valley.

.LONG TERM...(Monday through Friday)
Issued at 330 PM EST Fri Feb 24 2017

Agree with previous discussion that no major systems are on the
horizon, though the second half of next week could turn more active
with the synoptic pattern supporting the possibility of clipper
systems traversing the Great Lakes.

Mid level flow turns southwesterly by Monday with a surface low
expected to move into Central to Northern Lower Michigan by Tuesday.
H850 temps may hover around zero at the onset of this event but
surface temps look quite warm. It seems if any wet snow does occur
the impacts would be quite minimal before precip turns over to rain.
The precip may end as a mix of rain and snow into early Wednesday
but again we are expecting little to no impact from this.

H500 ridge amplification across the Rockies and Great Plains by the
second half of the week will act to keep our temperatures much
closer to normal for the start of March, though nothing drastically
cold at this point. The GFS, ECMWF, and GEM indicate a pattern
supportive of occasional clippers moving into the Great Lakes, thus
our chance for some snow showers should be increasing between
Thursday and the start of next weekend. Too early to say what our
prospects for accumulations will be.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 653 PM EST Fri Feb 24 2017

The area of thunderstorms associated with the cold front should be
east of our CWA (JXN taf site) by 02z. Behind that there is an
area of dense fog (BIV 1/4SM FG) that trails the system as it
departs since the surface wind does not pick up till between 03z
and 06z (west to east). When the stronger winds kick in so will
the light snow. For the KMKG, KGRR and KAZO taf sites there should
be a 4 to 6 hour period of IFR. The rest of the taf sites should
see only MVFR snow around sunrise till early afternoon. ALL areas
should see conditions improve to VFR by late afternoon.

&&

.MARINE...
Issued at 330 PM EST Fri Feb 24 2017

Will hoist a gale warning from the first half of Saturday as north
winds and cold advection kicks up the lake.


&&

.HYDROLOGY...
Issued at 1237 PM EST Fri Feb 24 2017

Widespread rainfall overnight will produce rises on area rivers
over the next few days. Rainfall was generally one quarter to one
half inch...with amounts in excess of one inch across northern
portions of Lower Michigan. Current forecasts keep all rivers
below flood stage...but additional rainfall today could produce
stronger rises. Heaviest rain today should fall over southern
sections of Lower Michigan...which received less rainfall
overnight.

Colder temperatures return for the weekend...with a series of storm
systems bringing additional precipitation to the region this week.
While temperatures are not expected to be cold enough for ice
formation on rivers...the additional precipitation could cause
slower recession or additional rises on area rivers.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory from 3 AM to 8 PM EST Saturday for
     MIZ037-038-043-050-056-064-071.

LM...Gale Warning from 7 AM to 2 PM EST Saturday for LMZ844>849.

&&

$$

SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...Hoving
AVIATION...WDM
HYDROLOGY...MWS
MARINE...JK



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