Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 161636

Area Forecast Discussion
National Weather Service Indianapolis IN
1136 AM EST Wed Jan 16 2019

The AVIATION Section has been updated below.


Issued at 354 AM EST Wed Jan 16 2019

Another early morning of patchy freezing drizzle across much of
central Indiana will be followed by another cloudy day. A low
pressure system moving toward the area tonight will bring chances
for snow and then rain to the area throughout the day on Thursday.
After that, a stronger system will arrive Friday night and bring
more snow and possibly some ice for Saturday/Saturday night. Windy
conditions and colder temperatures will arrive in the wake of
Saturday`s system, plunging central Indiana into the coldest
temperatures of the season.


.NEAR TERM /Rest of Today/...
Issued at 943 AM EST Wed Jan 16 2019

Mid level vorticity lobe currently dropping southeast through the
area is progged by short term model data to pass off to the
southeast by early this afternoon. Will hold onto some areas of
flurries/freezing drizzle/drizzle into the midday hours over the
central and southern zones.

Previous discussion follows.

Seeing reports of patchy freezing drizzle and light snow grains
across parts of central Indiana. Across the southern counties
temperatures remain above freezing, so just looking at patchy
drizzle there. Given the low level saturation in the soundings and a
very weak front slowly sliding south through the area am keeping the
patchy drizzle south, patchy freezing drizzle north and central
going through the mid morning hours. May see drizzle come to an end
after that, but also possible the front will stall more and patchy
drizzle/freezing drizzle will hang around into the afternoon.
Temperatures are within a couple degrees of freezing either way and
are likely to remain pretty steady into the late morning/early
afternoon when they could warm a couple degrees. Will continue with
SPS to highlight potential for some black ice and slick spots on
untreated roads.


.SHORT TERM /Tonight through Friday night/...

Issued at 354 AM EST Wed Jan 16 2019

Tonight a system will swing out of the plains and bring a warm front
moving into southern Indiana from the south, along with an upper
wave from the west. These will combine to provide forcing for
precipitation across central Indiana moving in the late night/early
Thursday morning hours and hang around through the day as the system
moves through. Models have cut back on the warm nose aloft and
instead are bringing in a layer of above freezing air at the surface
after saturation of the column and thus no longer look conducive for
freezing rain, and instead look more like snow transitioning to rain
from south to north. Decent isentropic lift and weak frontogenesis
along with the temperature profile remaining below freezing for much
of the day could mean over an inch of snow in the northern counties
by Thursday evening, with only perhaps a tenth of an inch possible
across the southern counties where mainly rain is expected.

This system will move out early Thursday night providing dry
conditions during the day on Friday. Late Friday night, though, the
next system will approach, again out of the plains but having a more
southerly track of the upper system than the first one. Soundings
show some potential for perhaps some brief sleet at precip onset,
but given the very brief nature and colder profiles in some other
models, will leave snow as the main precip type late Friday night
with some rain mixing in over the far southern counties.


.LONG TERM /Saturday through Tuesday Night/...

Issued at 359 AM EST Wed Jan 16 2019

The focus of the extended period remains on the snowstorm progged
for Saturday. The bulk of the precipitation is still expected to
move through between Sat 12Z to Sun 06Z. This is high confidence,
so raised the latest pops to categorical. The precipitation type
though is where confidence starts to wane. There still remains a
strong gradient separating the northern two-thirds of central
Indiana from the southern third with heavy snow over the northern
portions and a mix (even rain at times) across the south. So, just
the slightest shift in track could result in a big difference in
snow totals. At this time, the northern two-thirds of the forecast
area could see upward of 6 to 8 inches, but that southern third
could be as low as 1 to 3 inches.

As the system moves into the Mid-Atlantic states on Sunday,
precipitation will quickly end over central Indiana. However, a
cold snap will then ensue. Daytime highs for Sunday and Monday
will dip into the teens and 20s with overnight lows below zero on
Sunday night. However, the cold snap will be rather short with
temperatures returning to and above normal by Tuesday ahead of a
warm front. The associated surface low will then bring the next
round of snow accumulation to central Indiana as well starting
Tuesday. It won`t be quite as much as this weekend`s system, but
it will be measurable. Once again, it looks like mainly snow
across the northern half of central Indiana and a mix to the


.AVIATION /Discussion for the 161800Z TAFS/...
Issued at 1135 AM EST Wed Jan 16 2019

Most of the light mixed precipitation, and associated IFR
conditions, has diminished across the terminals as a mid level
vorticity lobe drifts off to the southeast.

Widespread MVFR ceilings 012-025 expected at the terminals through
this evening.

Light surface winds this afternoon will become 110-130 degrees at
4-7 kts by late evening.




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