Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 091926
AFDIWX

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

.SYNOPSIS...
Issued at 225 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
afternoon into this evening. Areas outside of the lake effect
belts will see scattered snow showers and flurries end by early
this evening. Mainly dry and continued chilly otherwise into later
tonight and Sunday with lows near 20 degrees tonight and highs
near 30 degrees tomorrow. The next system will bring renewed snow
and lake effect snow chances Monday into Tuesday. Remaining cold
otherwise next week.

&&

.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 18Z TAFS through 18Z Sunday Afternoon)
Issued at 1249 PM EST Sat Dec 9 2017

TAF focus on next 6 hours handling strong snow band that is
starting to leave KSBN with a mesolow upstream sending another NW
to SE oriented band back into the airport. Site has been at 1/4sm
for about an hour and expect slight improvement (which may be
brief) as aforementioned second band moves in. Radar returns not
as high at this time as current band but vsby of 1/2sm or less at
times can be expected. Have maintained temp group for now with
1/2sm, as there is no way to handle the highly variable vsbys with
these bands. Confidence in location and timing of main dominant
band of snow low given mentioned mesoscale features. Winds will
start out on the lighter side if not calm briefly as low passes
over KSBN, then will rapidly increase from the NW causing blowing
and drifting snow as well as continued snowshowers into this
evening.

At KFWA same band impacting KSBN will move towards the site and
cause some impacts, although hopefully in a somewhat weaker state.
Will monitor trends, but keep things somewhat optimistic. Once
this feature passes, airport may end up with little additional
activity. Will address that in the coming hours.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Winter Storm Warning until midnight EST /11 PM CST/ tonight for
     INZ003-004-012-014.

     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-
     015-016.

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.

OH...NONE.
LM...Gale Warning until 10 PM EST this evening for LMZ043-046.

&&

$$

SYNOPSIS...Steinwedel
SHORT TERM...Steinwedel
LONG TERM...Steinwedel
AVIATION...Fisher


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