Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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820
FXUS63 KGRR 140830
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
330 AM EST Sun Jan 14 2018

LATEST UPDATE...
Synopsis/Short Term/Long Term/Marine

.SYNOPSIS...
Issued at 330 AM EST Sun Jan 14 2018

Lake effect snow showers will impact the shoreline again today,
before a more widespread light snow develops tonight and continues
on Monday. Most locations will see an inch or so tonight and
another inch or two on Monday and the Monday morning commute
could feature slick conditions.

Additional snow showers are expected Monday night and Tuesday,
with the potential for several inches of lake effect snow around
South Haven. Cold air will stay with us through midweek then a
warmup will occur toward the end of the week with highs next
weekend up around 40.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 330 AM EST Sun Jan 14 2018

Localized snow accumulations of an inch or two are possible today
along the lakeshore, particular in the Muskegon and Grand Haven
areas. The low level flow continues to back, and good convergence
is progged along the coast (maximized near MKG around Noon) as
the southwest flow over Lk MI interacts with the overnight land
breeze.

Inversion heights today are relatively low around 5K ft, so the
snow should not get too out of hand. The coastal snow showers are
expected dissipate later today and this evening while lifting
north as the low level flow turns more southeasterly due to
apching synoptic system.

Really no change regarding the widespread synoptic light snow
tonight related to the warm advection/isentropic lift component of
the approaching low. A rather deep DGZ is progged but the
lift is meager. Only about an inch of snow is expected overnight,
but it may still be enough to make for a slick Monday morning
commute considering the cold sfc temperatures of 10-15.

On Monday the ocnl widespread light snow continues as the upper
low drops into Wisconsin and a shortwave and the sfc occlusion
pivot into the area from the southwest. The sfc occlusion/trough
is shown to set up in a west-east fashion across srn lwr mi on
Monday night into Tuesday and highest pops and additional light
snow amounts will be with the enhanced convergence along this
feature.

The big wild card in later periods is if and where the heavy mid
lake convergence band decides to come onshore. The northern end of
this band is expected to head toward Green Bay Sunday night and
Monday due to easterly flow north of the sfc low. However there is
some indication that the srn end of it will come onshore around
South Haven Monday night and Tuesday. This will need watched
since some impressive snowfall rates could develop if/where/when
it comes onshore.


.LONG TERM...(Tuesday night through Saturday)
Issued at 330 AM EST Sun Jan 14 2018

Lake effect snows will continue Tuesday night, but then should
gradually diminish Wednesday.  The flow should be NNW which will
favors western Allegan and Van Buren Counties to see the steadiest
snows, with lighter snows from U.S. 131 and west.  Mainly another
inch or two, localized 4 inches in western Allegan and Van Buren.

A pattern shift occurs Wednesday night and this should last into
next weekend.  The upper flow becomes more zonal, with surface high
pressure centered over the TN Valley Thursday.  This high moves to
the Carolinas by Friday night.  This brings a SW low level flow over
the Great Lakes region and H8 air around 0C pushes in. The models
are in much better agreement on this as compared to last night`s
runs. Daily high temps should moderate each day in this set up,
warming from the low 20s Wednesday, to around 40 by Saturday.  For
the most it looks dry in this period too, until perhaps Saturday
when we see a cold front move into the upper Midwest.  This may
bring some rain, possibly mixed with snow north.  Even higher
chances of rain should move in early next week as the front arrives.
Cold air and a change back to snow appears to not occur until Sunday
night.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1148 PM EST Sat Jan 13 2018

A band of lake effect snow was hugging the Lake Michigan coast. It
was occasionally moving in toward AZO. However the winds will be
shifting to the southwest prior to 09Z which will bring this band
inland, impacting MKG and perhaps GRR through the wee hours of the
morning. MVFR and patchy IFR will be seen within this band. The
band is expected to dissipate around 18Z.

Southerly winds will increase by early afternoon to around 10
knots, and then become gusty after 02Z. Snow will be arriving
toward the end of this forecast period with some possible IFR near
or after 06Z.


&&

.MARINE...
Issued at 330 AM EST Sun Jan 14 2018

We have considerable ice in the nearshore area, especially south
of Whitehall.

&&

.HYDROLOGY...
Issued at 1202 PM EST Sat Jan 13 2018

The colder temperatures that have moved back into the region will
cause ice to reform and solidify on area rivers into next week.
Additional flooding is not expected and rivers will likely be locked
down by the end of the weekend. Will still need to monitor rivers
for potential ice jam flooding.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&

$$

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



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