Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 280701
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
301 AM EDT WED SEP 28 2016

.UPDATE...
The SYNOPSIS, NEAR TERM, and SHORT TERM sections have been
updated below.

&&

.SYNOPSIS...
Issued at 301 AM EDT Wed Sep 28 2016

An upper level low will loiter in the area into the weekend, keeping
cooler than average temperatures and chances for rain in the
forecast. Warmer and drier conditions return next week.

&&

.NEAR TERM.../Today/
Issued at 301 AM EDT Wed Sep 28 2016

An upper low will move into the forecast area today. In addition, a
surface low will move into Ohio and drag a front through central
Indiana. Q-vector convergence progs show decent forcing with this
system today.

Rain will continue to develop this morning as the system approaches,
and currently it looks like the southern and eastern forecast area
will see the highest chances for rain as the front moves through the
area. Will go likely PoPs there later this morning into early
afternoon. (Hi Res Rapid Refresh has higher coverage of rain early
this morning across the northern forecast area. Will have to watch
for development and may up PoPs there early).

After the front passes, the upper low will be moving in with cold
air aloft. The steep lapse rates could lead to additional scattered
convection developing, so will keep chance PoPs going most areas mid
to late afternoon to account for this.

It now appears that there will be enough instability to go with a
thunderstorm mention everywhere across the area this afternoon. The
southeastern forecast area looks to perhaps have some brief
sunshine, which could lead to higher instability.

SPC has placed the southeastern forecast area in Marginal Risk, and
this looks reasonable given the expected instability and cold air
aloft moving in (creating a hail threat). Will mention hail in the
Hazardous Weather Outlook.

MAV MOS and model blend look cool with some potential for occasional
breaks in the clouds today. Went warmer, but not quite as warm as
the MET MOS.

&&

.SHORT TERM.../Tonight through Friday night/
Issued at 301 AM EDT Wed Sep 28 2016

Focus remains on chances for rain through the period. Models are
close enough that a blend was used.

As the upper low meanders out of and then back into Indiana, chances
for rain will continue through the Short Term. For much of the
period, PoPs will be in slight chance to chance category, with
highest PoPs generally across the eastern areas, closer to the upper
low.

Higher chances of rain will move in Thursday night into Friday, as
more potent energy rotates into the area from the northeast. Will go
high end chance category to low likely PoPs across the north during
that period, with chance PoPs south.

There is still some uncertainty on the path of the upper low and
thus locations and timing of better forcing, so some changes in the
forecast remain a good possibility through the next couple of days.

Generally stayed close to a model blend for temperatures, as MAV MOS
is too cool for highs at times.

&&

.LONG TERM /Friday Night through Tuesday/...

Issued at 220 PM EDT Tue Sep 27 2016

The ECMWF continues to keep the persistent upper low over the
Ohio Valley Friday night through Saturday...before it finally
begins to drift farther north on late Saturday night and Sunday.
ECMWF then suggests ridging aloft build across the
region...nudging the low to the northeast. Thus have kept with
superblends low chance pops from Friday Night into Saturday...then
trended toward a dry forecast early next work week as ridging and
high pressure resume. Expect below normal temperatures to continue
on Friday and early Saturday as the low lingers in the area...a
return to near normal highs is expected next work week as high
pressure builds across the region and warmer southerly flow tries
to develop.

&&

.AVIATION /Discussion for the 28/06Z TAFs/...

Issued at 1236 AM EDT Wed Sep 28 2016

VFR conditions may give way to MVFR in stratus and showers later
this morning across the sites as a large upper low drops into the
region.

Skies will quickly cloud up overnight as the upper low approaches.
Fluctuations in conditions will be likely on Wednesday, with the
lowest conditions likely in any showers or perhaps an isolated storm
or two.

Winds will become more northwesterly with time, and will be 10kt or
less throughout the period.

Visibilities will be unrestricted except for minor restrictions in
precipitation.

&&

.IND Watches/Warnings/Advisories...NONE.

&&

$$

SYNOPSIS...50
NEAR TERM...50
SHORT TERM...50
LONG TERM...PUMA
AVIATION...NIELD



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