Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 071747

Area Forecast Discussion
National Weather Service Northern Indiana
1247 PM EST Wed Dec 7 2016

Issued at 1226 PM EST Wed Dec 7 2016

Flow around a deep low pressure system north of Michigan continues
to push cold air into the Northern United States. With the cold air,
initially light lake effect snow occurs Thursday into Friday, but
becomes more intense later in the day Thursday. Significant lake
effect snow accumulations are expected especially Thursday night and
early Friday. Thereafter, high pressure returns for Saturday with
more settled conditions, but snow is expected to follow for Sunday
as a low pressure system moves through the area. Cold air, once
again, moves in following this system with a chance for more lake
effect snow early next week.


Issued at 1117 AM EST Wed Dec 7 2016

Some changes will be made midday regarding the current winter
weather headlines. The winter storm watch will transition to a
winter storm warning for Berrien/Cass/St. Joseph counties in
southern lower Michigan. The winter weather advisory will remain
in effect for surrounding counties of far northern
Indiana/southern lower Michigan with a slightly delayed start time
of 15Z. New 12Z guidance continues to support period of heaviest
lake effect snow from the late Thursday afternoon through Friday
morning. Given fairly consistent signals with lake effect
parameters and synoptic forcing for this period, will go ahead
with the upgrade at this time. An updated WSW will be sent by
around 17Z.


.SHORT TERM...(Today through Friday)
Issued at 444 AM EST Wed Dec 7 2016

A lake effect snow event will begin to unfold tonight as much colder
air spreads over the relatively warm water of Lake Michigan behind a
cold front. A secondary trof should move across the area late
Thursday and cause winds to veer a little more to the northwest.
Have issued a winter storm watch for lake effect snow and blowing
snow and a winter weather advisory for lake effect snow for late
tonight through Friday. Southern Lake Michigan remains
exceptionally warm for this time of year. Given thermal profiles,
lake fetch and instability, expect 5 to 8 inches over far
southwest Lower Michigan with lesser amounts farther inland by
late Friday. Inversion heights should begin to fall Friday as the
ridge axis approaches.


.LONG TERM...(Friday night through Tuesday)
Issued at 444 AM EST Wed Dec 7 2016

Lake effect snow will continue to diminish Friday night ahead of the
next system poised to arrive this weekend. Even the spectral models
such as the EC and GFS have really been struggling the past several
days handling the short wave energy with a broad and expansive upper
trof over North America. Went with the cooler GFS this weekend
favoring all snow Sunday, although can`t rule out a rain/snow mix
over southern areas. Confidence in any solution is even lower for
next week. A lot of cold air will be over the Canadian interior
stretching down into the Northern Plains with plenty of energy in
both the northern and southern streams. Cross/polar flow with bring
a fresh surge arctic air south, so the wintry pattern is set to
continue next week.


.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
Issued at 1226 PM EST Wed Dec 7 2016

High clouds are coming in from the south and cooler air coupled with
clouds are coming in from the north and west to start this period.
The cooler air will help to set off some light lake effect snow
showers that reach SBN overnight, but should stay north of FWA
due to a lack of a northerly component in the flow. Later
Thursday, a better chance for accumulating snow at SBN occurs.
CIGs north and west of SBN are already into MVFR, but some models
slow the trek of the clouds into SBN by around 00z.


IN...Winter Weather Advisory from 10 AM Thursday to 4 PM EST Friday
     for INZ004>007.

MI...Winter Weather Advisory from 10 AM Thursday to 4 PM EST Friday
     for MIZ080.

     Winter Storm Warning from 4 AM Thursday to 4 PM EST Friday for

LM...Small Craft Advisory until 7 AM EST Friday for LMZ043-046.



SHORT TERM...Skipper
LONG TERM...Skipper

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