Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 130644

Area Forecast Discussion
National Weather Service Northern Indiana
144 AM EST Wed Dec 13 2017

Issued at 132 AM EST Tue Dec 12 2017

A brief lull in the snow will continue for the remainder of the
overnight hours. However, another a fast moving clipper system
that will bring additional accumulating snow to much of the area
later today into tonight. Most of the snow accumulation is
expected northeast of Route 30. High temperatures today will range
from only the lower to mid 20s across south central Lower
Michigan, to the mid 30s across west central Indiana. Warmer
temperatures are then expected this weekend with highs in the mid
to upper 30s.


.SHORT TERM...(This Evening through Wednesday)
Issued at 327 PM EST Tue Dec 12 2017

...Lake effect event well underway...
...Strong clipper system to impact area Weds/Weds Ngt...

3 bands with varying degrees of dominance have been impacting
parts of the forecast area for much of the day. Eastern 2 bands
have shown signs of weakening as western most band, from LaPorte
county into Marshall and SE from there, has become the strongest
as wind begins to shift and causing increase in convergence.
Sporadic reports of 3 to 6 inches of snow under areas where bands
have been persisting. Amounts have been somewhat limited by
cellular nature of much of the activity as well as transitory
nature. Winds will slowly back westerly and eventually
southwesterly in advance of clipper system to deal with starting
Weds. Until this happens, lake effect bands will persist with at
least some additional accumulations likely. All headlines will
remain in place at least through this evening with potential to
begin clearing as bands shifts eastward. Additional accumulations
will range from a trace to several inches before all is said and
done. Winds have been causing blowing and drifting issues with a
slow decrease expected through the evening.

No time to catch our breath as once this event ends another will
quickly start Weds AM as strong Alberta Clipper will race southeast
tonight with surface low tracking somewhere over the forecast area.
Models generally in agreement of highest slug of moisture being
roughly from Muskegon to Detroit as the surface low tracks from
Chicago to Columbus during the afternoon and evening hours. However,
the forecast area is not out of the woods for accumulating snowfall
as wing of warm air advection will allow for light snow in NE areas
in the morning, followed by enough moisture being squeezed out
along/behind the clipper to bring light snow to much of the area
during the afternoon/evening hours. Have kept with higher pops (even
expanded somewhat from previous shift) and nudged up amounts,
especially NE. Portions of the area will likely need winter weather
headlines, but with ongoing event and some of the same counties in
headlines now may need them tomorrow will defer to either eve shift
or overnight shift to issue.

Brief lake response will commence in the wake of the low, much
closer to the lake this time around. Some spots could see an inch or
so warranting higher pops. Away from the lake clouds and with fresh
snow cover in place, overnight lows Thurs morning will drop to well
below normal levels in the single digits with wind chills
approaching zero.


.LONG TERM...(Wednesday Night through Tuesday)
Issued at 327 PM EST Tue Dec 12 2017

Another in the series of a clipper type of system will move across
the Great Lakes Region Thursday and Friday. The surface low track
with this system will be far to the north of the forecast area over
Upper Michigan. Some warm air advection type of snow is possible
mainly Friday and Friday night; and with some lake enhancement, may
be able to generate an inch or two of snow over far northern Indiana
into Lower Michigan. Milder air will spread into the area Saturday
through Monday with little if any precipitation expected.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday Night)
Issued at 128 AM EST Wed Dec 13 2017

Crashing inversion heights and slowly backing winds have eroded
lake effect snow showers. Two distinct upstream waves are being
monitored for additional snow chances later today. The better
chance of initial warm advection surge snow will likely remain
just north of terminals, but better chances of snow should arrive
after the 18Z-20Z timeframe as one of these two upstream waves
across the Northern High Plains approaches the western Great
Lakes. The secondary wave will drive a cold front southward this
evening with a period of light synoptic snow expected for most of
northern Indiana. Cigs should trend into the 1500-2500 ft range
this evening as this occurs with improvement back to VFR likely
not long after the end of this forecast valid period. In addition
to the potential of more accumulating snow today, south-southwest
winds ahead of this system will become somewhat gusty to around 20
knots late morning/afternoon before veering more north-northwest
tonight as sfc reflection tracks across the region.


LM...Small Craft Advisory until 3 PM EST this afternoon for LMZ043-



LONG TERM...Fisher

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