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FXUS63 KIWX 122333

Area Forecast Discussion
National Weather Service Northern Indiana
633 PM EST Tue Dec 12 2017

Issued at 330 PM EST Tue Dec 12 2017

A few bands of heavy lake effect snow will diminish into this 
evening as very cold air spreads over the region. Several inches 
of accumulation are expected along with blowing and drifting snow 
especially north of Highway 30. The snow should temporarily 
diminish tonight ahead of another fast moving clipper system that 
will bring additional accumulating snow to much of the area
Wednesday and Wednesday evening. 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 00Z TAFS through 00Z Wednesday Evening)
Issued at 633 PM EST Tue Dec 12 2017

Dry entrainment impinging along wrn bound of current lake effect as 
well as relaxing low level thermal trough within slowly backing flow 
will continue to whittle away at ewd progressing snow bands. Thus 
expect snow will end quickly this evening across the terminals 
leaving VFR conditions behind.

Next upstream approaching wave dropping out of Alberta looks quite 
robust in sat imagery this evening and will amplify rapidly sewd 
overnight. Good low level warm advection response anticipated with 
snow redeveloping near/just after daybreak. 

 Three main bands of lake effect snow have emerged coming out of 
Lake Michigan and have been moving well inland. SBN has been in a 
dry area between the middle of the 2 west bands; although the east 
band has been tracking over the vicinity of FWA. Have adjusted TAFs 
accordingly with lower conditions as FWA. The next clipper is just 
upstream and will cause the ongoing bands to end quickly as winds 
back. More snow is possible late in the TAF period as this next 
system approaches. 


IN...Winter Weather Advisory until 7 AM EST Wednesday for INZ014-

     Winter Storm Warning until 7 AM EST Wednesday for INZ004>006-008.

     Lakeshore Flood Advisory until 3 PM CST this afternoon for 

     Winter Weather Advisory until 6 PM CST this evening for INZ003.

MI...Winter Storm Warning until 7 AM EST Wednesday for MIZ077>079.


LM...Small Craft Advisory until 4 PM EST Wednesday for



LONG TERM...Fisher

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