Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 231946
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
346 PM EDT Sun Jul 23 2017

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

&&

.SYNOPSIS...
Issued at 314 PM EDT Sun Jul 23 2017

Thunderstorm activity across central Indiana will come to an end
tonight as a cold front exits the area and cooler drier air
filters in. Dry weather is then expected through Wednesday as high
pressure builds over the area from the northwest. The next system
will arrive late Wednesday night as a cold front approaches and
then moves through the area on Thursday. Shower and thunderstorm
chances continue into Thursday night but move out by Friday and a
dry weekend is in store.

&&

.NEAR TERM /This afternoon and tonight/...

Issued at 314 PM EDT Sun Jul 23 2017

Scattered line of thunderstorms moving through central Indiana
this afternoon will continue to sink southeast through this
evening. The best upper forcing is north of the area but surface
convergence along cold front and leftover convective boundaries
will continue to provide the focus necessary to sustain scattered
convection across much of the area in this warm humid airmass for
the next few hours. The building upper ridge will start to push
any storm chances out from the southwest as it serves to stabilize
the airmass. Some additional convection from the north could move
during the tonight period or hang around for the first few hours
of that period on the leading edge of the upper wave moving south
through Wisconsin currently. Thus will keep chance pops going in
the north through around 3z and slight chance elsewhere before
dropping to dry by 6z with instability dropping out. With all the
rain received in parts of the area could wind up seeing some
patchy fog development late, but complicating this will be cold
dry advection behind the front. Thus only included this in the
southern half of the forecast area starting after 9z and running
through daybreak.

&&

.SHORT TERM /Monday through Wednesday/...

Issued at 314 PM EDT Sun Jul 23 2017

Models are in pretty good agreement and did not deviate from
blended initialization. High pressure builds over the area from
the northwest and will bring dry weather and initially cooler
temperatures to the area. Highs in the low to mid 80s are expected
for Monday and Tuesday with dew points back in the more
reasonable 60s. Wednesday as the high moves to the east through
the day temperatures will climb back into the upper 80s to around
90 and dew points into the upper 60s to lower 70s.

&&

.LONG TERM /Wednesday Night through Sunday/...
Issued at 228 PM EDT Sun Jul 23 2017

Models indicate low pressure will move across the great lakes
Wednesday night and a cold front will move south across Indiana
later Thursday and Thursday night.  There are some timing
differences with the GFS and Canadian models being a little faster
and the Euro a little slower.   The GFS tracks a stronger low
pressure system across the mid Mississippi valley into Kentucky
by Friday and as a result slows down the cold front then.
The GFS and Canadian models are a little more progressive then
and I decided to cut super blend POPS slightly north and central
Friday.

Otherwise...models are in good general agreement with Thursday
being quite wet and Friday night and the weekend being dry as
high pressure moves east across the great lakes.

Overall the MOS blend on temperatures seem reasonable. Lows will be
in the upper 60s to lower 70s Wednesday night...middle to upper
60s Thursday night and the lower 60s over the weekend.  Highs will
be in the 80s with some upper 70s over northeast sections Saturday.

&&

.AVIATION /Discussion for 231800z TAF issuance/...

Issued at 123 PM EDT Sun Jul 23 2017

Broken MVFR cloud deck has developed over the sites. Expect that
ceilings will increase to VFR over the next few hours with
increased solar insolation as cirrus deck exits.

On convective threat...storms are moving through KLAF at issuance
time but should be southeast of there shortly so included a VCTS
there but no explicit mention. Was going to leave VCTS out of KHUF
and KBMG for this issuance, but latest look at satellite and radar
trends show move convective development ahead of the cell at KLAF
and also an area of convergence in central Indiana that could lead
to scattered storm development over the next couple of hours. Thus
will include a VCTS at all sites, likely through around 23-0z. Any
sites that do see storms will likely see a brief drop to LIFR
visibilities and possibly IFR ceilings with gusty NW winds around
25-35 kts.

Tonight could see some fog development from saturated ground, but
cool and dry advection behind the cold front may counteract this,
so just included a tempo mention at KBMG where the drier air will
arrive the latest.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...CP
NEAR TERM...CP
SHORT TERM...CP
LONG TERM....JH
AVIATION...CP



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