Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 131749
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1249 PM EST Fri Jan 13 2017

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

&&

.SYNOPSIS...
Issued at 256 AM EST Fri Jan 13 2017

Central Indiana`s luck looks to be poor as wintry precipitation will
likely cause some travel problems this weekend. A front will remain
stalled out across the Tennessee Valley, with waves moving long the
front. High pressure to the north will provide a source for cold air
flowing into the area. The result will be the wintry precipitation.
Additional fronts will bring frequent chances for rain next week.

&&

.NEAR TERM.../Today/
Issued at 256 AM EST Fri Jan 13 2017

Isentropic lift will increase from the south during the day
(especially this afternoon) as winds aloft increase from the south
across a temperature gradient. Meanwhile, at the surface, northeast
to east winds will continue to provide a flow of dry air which any
precipitation will initially have to overcome.

Skies will start out partly to mostly cloudy, but clouds will
increase as the lift increases. This will allow some sunshine at
some locations, but don`t think this will be enough to help boost
temperatures to MOS numbers most areas. Will go closer to a blend.

With warm temperatures aloft and initially cold temperatures at the
surface, precipitation type could start out as freezing rain south.
However, most areas will warm enough for just rain by mid afternoon.

Will keep PoPs in chance category most areas, with much of the
northern forecast area remaining dry all day.

Feel that the threat for freezing rain today across the south is too
low to change the start time of the Advisory.

&&

.SHORT TERM.../Tonight through Sunday night/
Issued at 256 AM EST Fri Jan 13 2017

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

Better chances for precipitation arrive tonight into Saturday
morning as lift increases aloft and an wave moves along the front.
Best chances will be across mainly the southern half of the area
closer to the wave. Will go likely PoPs across much of the southern
half of the forecast area at some point tonight into Saturday
morning, with lower PoPs north.

Soundings indicate that freezing rain should be the primary
precipitation type across the area during tonight into Saturday
morning, with southern areas turning to rain during Saturday
morning. (There could be some sleet mix in tonight as the
precipitation begins.) Fortunately, precipitation amounts look to
remain relatively light. Of course any amount of freezing rain can
cause issues for travel, but the light amounts should spare trees
and power lines from damage. Given this, the Advisory looks good for
the area into Saturday.

Some concern about temperatures Saturday afternoon with some models
keeping temperatures closer to freezing. This would prolong any
issues, mainly across the northern forecast area, during the
afternoon. Generally went below MOS for highs on Saturday.
(Ageostrophic flow from the right rear quadrant of an upper jet will
likely reinforce the colder air across the northern forecast area).

There looks to be a relative lull in the precipitation later
Saturday afternoon into Sunday morning as forcing weakens. Soundings
do indicate a low potential for freezing drizzle, and impacts from
previous freezing rain will likely continue. This will not change
the Advisory Saturday night into Sunday at this time.

Precipitation chances increase Sunday afternoon into Sunday night as
a warm front moves in from the south. The northern forecast area
could see some additional freezing rain during this time. Will have
to watch this time period closely as well. For now, PoPs will remain
in the chance category.

As is the case in these situations, a small change in temperature
could have big impacts on precipitation type. Stay tuned.

&&

.LONG TERM (Monday night through Friday)...

Issued at 1250 PM EST Fri Jan 13 2017

Expect mild temperatures with a lot of rain. There is
considerable uncertainty about the details.

Early in the period, there is significant model disagreement about
the track of low pressure over the area.  This leads to uncertainty
of up to 7 degrees for temperatures and 20 percent for precipitation
chances. However, temperatures seem likely to stay above freezing
and rain is probable at times.

Starting Thursday, there is better model alignment. Forecast
confidence increases. Potential errors in temperatures decline to
3 degrees and potential errors in rain chances to about 10
percent.

The consensus from Region will be used.


&&

.AVIATION /Discussion for the 131800z TAF Issuance/...
Issued at 1211 PM EST Fri Jan 13 2017

VFR Conditions are expected to deteriorate to MVFR and worse in
freezing rain 00z-02z at BMG, HUF and IND 00z-02z tonight and a few
hours later at LAF. Precipitation coverage will drop off after 16z
Saturday as high pressure re-establishes over the upper Midwest.
However, flying conditions will be poor.

Winds will be east and northeast less than 10 knots.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
Freezing Rain Advisory from 7 PM this evening to 1 PM EST Sunday
for INZ021-028>031-035>049-051>057-060>065-067>072.

&&

$$

SYNOPSIS...50
NEAR TERM...50
SHORT TERM...50
LONG TERM....JK
AVIATION...MK



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