Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 210812

Area Forecast Discussion
National Weather Service Indianapolis IN
312 AM EST Sun Jan 21 2018

The LONG TERM Section has been updated below.


Issued at 327 PM EST Sat Jan 20 2018
The warm-up has started across central Indiana with highs climbing
into the mid 40s this afternoon. Temperatures will rise even
further the next few days with highs topping off in the 50s as
flow remains southerly. However, the low clouds have spread into
the area as Gulf moisture is pumped into the region ahead of the
next system. Patchy fog, drizzle and rain showers will be the
norm through the weekend and into next week. Cooler temperatures
will briefly return around mid-week, but then another warm-up and
dry conditions can be expected in the extended period.


.NEAR TERM /Tonight/...

Issued at 327 PM EST Sat Jan 20 2018

The current synoptic set-up has an area of low pressure rotating
over the Deep South. This disturbance is helping to pump Gulf
moisture into the forecast area from the southwest. In addition,
low clouds are also infiltrating the area from the west as well
ahead of a low pressure system over the Four Corners Region. As
the night wears on, the chances for drizzle and patchy fog will
also increase, reducing visibilities. As far as temperatures,
generally stuck close to guidance with overnight lows in the mid
30s to low 40s.


.SHORT TERM /Tomorrow through Tuesday/...

Issued at 327 PM EST Sat Jan 20 2018

The main focus of the short term period will continue to be the
above normal temperatures and rainfall chances with a low pressure

Rain chances will increase further tomorrow as a low pressure
system continues its track into the Central Plains. Central
Indiana will generally stay in the warm sector for the duration of
this system though with high temperatures climbing into the 50s on
Sunday and Monday. Meanwhile, overnight lows will be in the 30s
and 40s.

Latest model runs continue to show the best rain chances from
Sunday night through Monday afternoon when isentropic lift is
strongest. Dynamics and confidence are still not high enough
though to insert mention of thunder. So, will continue to leave
it out of the forecast. A tight pressure gradient will result in
strong southerly winds on Monday and Monday night though with
sustained speeds of 10 to 15 mph, gusting to 25 mph.

As slightly cooler air mixes in behind an associated cold front
on Monday night, rain will slowly transition to a rain/snow mix.
Temperatures closer to normal for this time of year will then
prevail on Tuesday with highs in the mid to upper 30s. The
rain/snow showers will taper off through the day on Tuesday.


.LONG TERM /Wednesday through Saturday/...

Issued at 251 AM EST Sun Jan 21 2018

As has been the case the past few days, the main storm track has
shifted to more of a west-to-east across the CONUS. This has
moderated temperatures and it looks like, for the most part, this
will be the case through this period.

Wednesday will start off with a mid/upper level trough effecting
the earlier periods moving off to the east and high pressure
centered over the mid/southern Plains moving eastward into the
Tennessee Valley to the south. This will result in a dry period
through Thursday with temperatures around normal for Wednesday,
then warming to the mid-upper 40s during the day as the high moves
off to the east.

A minor wave at mid levels is forecast by the models to move
northeast through the area going into Friday, but no precipitation
is expected at this time. As this feature minors out Friday
afternoon, the next mid/upper level trough will move in for the
later periods with warm air advection ahead of the accompanying
frontal boundary late Friday/early Saturday. As with the frontal
boundary earlier in the week, this next cold front will result in
widspread rain and possibly isolated thunderstorm with it as it
enters the state Saturday afternoon. High temperatures on Friday
and Saturday will be well above normal with 50s in the southern
half of our area and low temperatures in the low-mid 30s Friday
and in the 40s going into Saturday.


.AVIATION /Discussion for 210600z TAF issuance/...

Issued at 1135 PM EST Sat Jan 20 2018

High confidence in poor flying conditions through the overnight
and much of the day on Sunday. Visibilities will be running around
and under 1SM at all sites but KBMG through the night with drizzle
and fog. Ceilings will likely be around 300 ft, again with the
exception of KBMG. Conditions at KLAF will worsen through the
night, and KBMG will likely worsen near daybreak. Visibilities
will improve during the day on Sunday, but ceilings will remain

A low level jet will bring LLWS to all sites but KLAF through the
night and much of Sunday. Chances for widespread rain will
increase Sunday night.




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