Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 141430
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
930 AM EST Sat Jan 14 2017

.UPDATE...
The NEAR TERM Section has been updated below.

&&

.SYNOPSIS...
Issued at 306 AM EST Sat Jan 14 2017

The freezing rain threat will continue at times into Sunday across
central Indiana as the area remains in the transition zone between
cold air to the north and seasonable air to the south. Warmer
temperatures return for Monday through next week, but a series of
systems will keep frequent chances for rain in the forecast.

&&

.NEAR TERM.../Today/
Issued at 930 AM EST Sat Jan 14 2017

Based on latest obs, took the rain and freezing rain line further
north to very near Interstate 70. Heaviest echoes were moving across
areas south of 70. However, more echoes across east central Illinois
west central Indiana will move across the northern forecast area
this morning and could cause some icy issues with temperatures only
in the upper 20s. Will continue with Advisory.

Previous discussion follows...
Issued at 306 AM EST Sat Jan 14 2017

Some light freezing drizzle is falling across parts of central
Indiana early this morning, but much of the area is dry.

Another wave will move across the area today, bringing more
precipitation with it. Precipitation with this wave is moving across
Missouri and western Illinois at the moment. Current hi res model
progs have the main part of the precipitation moving into the
western forecast area near 12Z and then spreading east during the
morning.

Temperatures at the moment are in the upper 20s north, around 30
central, and just above freezing south. These should change little
this morning, so expect freezing rain to be the dominant
precipitation type across most of the area (thanks to continued warm
air aloft). The far southern forecast area might be predominantly
rain, but can`t rule out some freezing rain initially.

By early afternoon precipitation will be mainly rain from I-70 and
south, with a mix north. However, precipitation chances will
diminish during the afternoon as the wave exits.

Will go likely PoPs most areas this morning, with chances lowering
during the afternoon. Precipitation amounts look to be light (less
than 0.10 inch).

Much of the northern forecast area will see it`s first round of
freezing rain this event. As noted earlier, far southern areas will
be mainly rain, but some brief periods of freezing rain can`t be
ruled out early this morning. This plan to keep the advisory intact
all areas today.

Went below MOS temperatures for the most part, closer to a blend of
raw model output.

&&

.SHORT TERM.../Tonight through Monday night/
Issued at 306 AM EST Sat Jan 14 2017

Models are close enough that the SuperBlend initialization
was accepted for most items.

High pressure will nose into the area tonight from the north,
keeping most of the forecast area dry. Far southern areas could see
some light precipitation, and temperatures will be cold enough for
this to be some freezing rain. However, PoPs will be in the slight
chance category as forcing is weak.

Additional weak waves will move into the area Sunday into Monday
morning, allowing for slight chance or chance PoPs. Temperatures
will be cold enough for a wintry mix at times Sunday morning and
again Sunday night into Monday morning across parts of the area.

Better forcing will arrive later Monday afternoon and Monday night
as an upper low moves into the Mississippi Valley. Thus the
initialization`s likely or higher PoPs were accepted. Warmer air
will flow into the area, so all precipitation will be rain Monday
afternoon and beyond.

With much of the forecast area remaining dry tonight, there is a
temptation to expire the advisory early. However, far southern areas
still have a small chance for freezing rain, and many areas will see
a low threat for freezing rain again Sunday morning. Rather than
cancel and perhaps have to reissue an advisory again Sunday, will
let the advisory run as is for now. Will mention in the product how
there will be a lull in freezing rain chances tonight.

&&

.LONG TERM /Tuesday through Friday/...

Issued at 139 AM EST Sat Jan 14 2017

ECMWF keeps a warm and progressive SW flow in place across the
area during this period. A warm front is expected to push across
Indiana on Tuesday as a strong trough across the region slowly
works through the state...providing ample forcing. A stronger Cold
front is then expected to pass on Wednesday as the strong trough
aloft departs. Thus will focus best pops during this extended
forecast on Tuesday and Wednesday.

ECMWF suggests ridging beginning to build across the region on
Thursday into Friday a highly amplified and active pattern remains
in place aloft. Overall...forcing and lower level features appear
limited on Thursday and Friday...thus will leave pops out for now.

Temps will remain well above normal through the period as the
prevailing west to southwest flow aloft continues to keep cold air
bottled up well to the north.

&&

.AVIATION /Discussion for the 141500z IND TAF Update/...
Issued at 920 AM EST Sat Jan 14 2017

IFR conditions to continue through the day. Temperature at the
freezing mark and should nudge above it around noon. So, left
freezing rain in through noon.

Previous discussion follows...
Issued at 547 AM EST Sat Jan 14 2017

IFR Conditions with possible freezing precipitation is possible
over the first 6-8 hours of the TAF period. Some improvement to
MVFR is expected this evening before improvement to VFR is
expected overnight.

Radar shows a wave of precipitation within the WSW flow aloft
pushing toward the TAF sites on the north side of the the stalled
frontal boundary to the south. This wave will push across the TAf
site this morning with some Freezing rain expected mainly in
locations along and north of I-70....where temps are below
freezing. HRRR shows this wave exiting the area shortly after
18Z-20Z. and Time heights show best lift is lost at that time.
Thus will trend toward improving conditions at that point.

Surface High pressure over the upper midwest then is expected to
build across the TAF sites tonight...allowing a return to VFR as
Time Heights show dry air within the column.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
Freezing Rain Advisory until 1 PM EST Sunday for INZ021-028>031-
035>049-051>057-060>065-067>072.

&&

$$

SYNOPSIS...50
NEAR TERM...50/MK
SHORT TERM...50
LONG TERM....Puma
AVIATION...JP/MK



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