Area Forecast Discussion
Issued by NWS Northern Indiana

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855
FXUS63 KIWX 081616
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
1116 AM EST Thu Dec 8 2016

.SYNOPSIS...
Issued at 1223 AM EST Thu Dec 8 2016

A strong low pressure system moving slowly east across
southeast Canada will cause cold west to northwest winds across
the Great Lakes resulting in significant lake effect snow over
southwest Michigan and far northern Indiana over the next couple
of days, with scattered snow showers over northwest Ohio and most
of the rest of northern Indiana. A low pressure system is
expected to move east across the Midwest this weekend causing snow
in our area, mainly Saturday night and Sunday. This system should
be followed by colder air overspreading the area into the middle
of next week with probably additional lake effect snows.

&&

.UPDATE...
Issued at 1046 AM EST Thu Dec 8 2016

Broad cyclonic flow, cold advection, and steep lapse rates have
allowed for lake effect snow showers to develop along with lighter
snow showers/flurries across much of the forecast area this
morning. Snow accumulation likely all not that efficient through
early PM as deepening mixed layer slowly begins to saturate better
snow growth layer. Snow shower intensity should pick by this
evening as next mid level trough sags across southern Great Lakes
and lake induced equilibrium levels increase to 8-10k feet. Fetch
considerations still suggest zone of greatest potential
accumulation from northern Berrien through Cass and St Joseph
counties, and possibly into Branch county. Some concern that
Branch county may need to be transitioned to a warning depending
on how things set up this evening, but confidence is not high
enough at this time to change headlines. Did go ahead and issue a
winter weather advisory for Hillsdale with expectation that
favorable fetch could result in 2 to 5 inch type accumulations in
western portions of the county. Did make some adjustments to
diurnal temps this afternoon showing little if any temperature
recovery in some spots due to the cold advection. Updated WSW has
been sent with Hillsdale addition to the advisory.

&&

.SHORT TERM...(Today and Tonight)
Issued at 534 AM EST Thu Dec 8 2016

Lake effect snow was already beginning north of Berrien county as
colder air was spreading over the relatively warms waters of Lake
Michigan. Few changes were made to the ongoing grids and forecast,
although have added Laporte County to the advisory given wintry
weather of blowing and drifting expected over far northern areas of
the county late today and tonight. The Lake Michigan water
temperatures over these southern portion of the lake around 45
degrees were exceptionally very warm for this time of year. Delta T
values will reach or exceed 20C with the cloud area very favorable
for snow growth. However, limited lake fetch, especially early along
with significant shear in the cloud layer will limit accumulations.
Have kept 5 to 8 inches over the advisory area, with lesser amounts
farther inland. Snow will diminish Friday as inversion heights
fall.

&&

.LONG TERM...(Friday through Wednesday)
Issued at 534 AM EST Thu Dec 8 2016

More cold and snowy weather is on the horizon for the extended.
Favor a general model blend for the approaching upper level system
this weekend. There was still considerable spread among GFS ensemble
members, so confidence in timing, track and snow amounts still
uncertain. Some members and the EC were warmer Sunday suggesting a
possible rain/snow mix. For now, kept all snow. Accumulations of
several inches are possible from Saturday through early Monday.
Otherwise, much colder air should spread over the area by Wednesday
along with snow and lake effect snow showers.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday Morning)
Issued at 601 AM EST Thu Dec 8 2016

Lake effect snow bands expanding southward over swrn MI should
impact sbn with grdly lowering vsbys today and mainly ifr
conditions anticipated for tonight as winds veer nw. Sgfnt lake
effect -shsn impacts expected to remain north of fwa with just
mvfr cigs and slight vsby restrictions in -shsn through the
period. Brisk westerly winds will continue to gust into the
20-25kt range through this eve, then slowly diminish.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Winter Weather Advisory until 4 PM EST /3 PM CST/ Friday for
     INZ003>007.

MI...Winter Weather Advisory until 4 PM EST Friday for MIZ080-081.

     Winter Storm Warning until 4 PM EST Friday for MIZ077>079.

OH...NONE.
LM...Small Craft Advisory until 7 PM EST Friday for LMZ043-046.

&&

$$

UPDATE...Marsili
SYNOPSIS...JT
SHORT TERM...Skipper
LONG TERM...Skipper
AVIATION...JT


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