Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 092317

Area Forecast Discussion
National Weather Service Northern Indiana
617 PM EST Sat Dec 9 2017

Issued at 616 PM EST Sat Dec 9 2017

Heavy lake effect snow will continue to impact portions of
northwest Indiana and far southwest Lower Michigan late this
evening before diminishing to flurries through southern Michigan
after midnight. Otherwise dry and chilly through Sunday. Lows
tonight near 20 with highs Sunday afternoon near 30. Another Alberta
clipper will bring renewed snow and lake effect snow chances Monday
afternoon through Tuesday.


.SHORT TERM...(This Afternoon through Sunday)
Issued at 150 PM EST Sat Dec 9 2017

Heavy lake enhanced/effect snow will remain the story well inland
into the evening hours. A classic type 6 MESOVORT, no doubt
enhanced under the synoptic scale sfc reflection this morning, has
worked inland into north-central IN as of 1830z. Whiteout
conditions and 1-2"/hr snowfall rates have been observed with this
feature. The hope is for this mesovort and snowfall rates/impacts
to weaken some as it tracks toward or just southwest of the Fort
Wayne area within the next few hours. Will cover with a SPS if
needed. Otherwise the main focus is turning to the developing
dominate single band in areas under warnings and advisories.
Radar/satellite show the main convergent axis along the long axis
of Lake MI with another separate band southwest from near Muskegon
MI. Strong low level flow will force this band well
inland...mainly west of US 31 this afternoon...then gradually
shifting east and weakening a bit with time to the US 31 corridor
early evening and to or just west of Hwy 15/US 131 mid evening.
Whiteout conditions/1-2" per hour rates/blowing snow can be
expected within this band.

Only a few leftover light snow showers or flurries off the lake
then by later tonight into Sunday morning as backing
winds/drying/subsidence take a toll on inversion heights. The next
weak/trailing pv filament and associated subtle sfc trough swings
through later Sunday afternoon/early evening. This weak forcing
coupled with some lake enhancement could be enough to generate a
few light snow showers or flurries mainly north of US 20 in far
nrn IN/lower MI.


.LONG TERM...(Sunday Night through Saturday)
Issued at 225 PM EST Sat Dec 9 2017

Perturbed/cold northwest flow will persist into next week as several
clipper systems ripple through bringing snow chances and reinforcing
shots of cold air. The first system to watch will be Monday into
Tuesday as shortwave and attendant sfc low take a track east
through the Lower Great Lakes by Monday aftn/eve...then deepening
a bit into the Eastern Great Lakes by early Tuesday given some
phasing with a trailing pv anomaly. Model trends today have been a
little farther south with leading WAA/isentropic snow (1-3"?)
Monday into Monday evening, best chances still north of US 30. CAA
wing then wraps in later Monday night into Tuesday with colder
temps and another round of LES. LES and additional chances for
weak clipper systems will result in additional more light snow
chances mid-late week. Eastern conus troughing does look to relax
by next weekend. This could result in a decent, yet brief, warmup
into Saturday and possibly Sunday.


.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 616 PM EST Sat Dec 9 2017

Near term focus on torrid lake single band about to overtake KSBN
terminal. Passage of parent sw through ern IN had allowed
for rapid upstream development/organization of intense single band
within maximized low level thermal trough. This feature will
translate slowly ewd over the next several hours yet begin to
diminish with swd extent as convergent boundary layer flow relaxes
and dry entrainment begins. Thus a period of LIFR restriction likely
invof KSBN yet this evening followed by rapidly improving flight
conditions after about 04z.

Transitory MVFR cigs invof KFWA early with improvement following
toward midnight.


IN...Winter Storm Warning until midnight EST /11 PM CST/ tonight for

     Lakeshore Flood Advisory until midnight CST tonight for INZ003.

     Winter Weather Advisory until 7 PM CST this evening for INZ013.

     Winter Weather Advisory until midnight EST tonight for INZ005-

MI...Winter Storm Warning until midnight EST tonight for MIZ077.

     Lakeshore Flood Advisory until 1 AM EST Sunday for MIZ077.

     Winter Weather Advisory until midnight EST tonight for MIZ078.

LM...Gale Warning until 10 PM EST this evening for LMZ043-046.



SHORT TERM...Steinwedel
LONG TERM...Steinwedel

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