Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 280838

Area Forecast Discussion
National Weather Service Indianapolis IN
438 AM EDT THU JUL 28 2016

Aviation sections updated


Issued at 337 AM EDT Thu Jul 28 2016

An active pattern continues with a frontal boundary stuck in the
area and upper troughing bringing a series of upper waves to
interact with it. This will continue until early next week when
upper ridging starts to build back in over the area and the trough
kicks east.


.NEAR TERM /Early this morning and today/...

Issued at 337 AM EDT Thu Jul 28 2016

Radar loop at 330 am is showing showers and thunderstorms across
much of south central Indiana. Given the available moisture these
are very efficient rainfall producers with rainfall rates over 2-3
inches an hour at times. Included categorical rain over this area
and mention of heavy rainfall potential into later this morning.
Expect this to continue during the next few hours and then shift
east during the mid morning hours as the upper wave enhancing
convergence along the 850 mb front moves off to the east. Later
during the afternoon could see another wave enhance convergence
along the front which should shift a little north as the wave
approaches. Thus bring the chances for storms north during the
afternoon. With low confidence on where the front will set up
though kept PoPs for today after this first wave moves out in the
chance category. That plays into uncertainty on an axis of heavier
rainfall as well, and thus no headline for flood potential at this
time as northern counties are drier. If convective development
sets up across southern counties again this afternoon expect flash
flooding to develop rather quickly.

For temperatures think much of the day will spent with cloud
cover but still have warm advection aloft. Went with consensus in
the mid 80s.


.SHORT TERM /Tonight through Saturday night/...

Issued at 337 AM EDT Thu Jul 28 2016

A diffuse surface front with an upper trough bringing waves
through the area will keep thunderstorm chances in the forecast
through the short term. Low confidence on timing of any particular
wave so kept to consensus of mid range chances for thunderstorms
throughout, with slightly lower PoPs Saturday night as forcing
then looks a little less evident. For temperatures did not deviate
from a model blend, where more sunshine and less precip on any of
the days could increase highs several degrees or an all day
washout (not anticipated but not to be ruled out either) could
do the same in the opposite direction. Humid atmosphere will
remain in place though, with no model indications of dewpoints
dropping below 60s and most of the time hanging in the upper 60s
to lower 70s. Due to the ample moisture and slow storm motion,
heavy rainfall leading to flooding will be a threat but too low
confidence on location or timing to go with headline.


.LONG TERM /Sunday through Wednesday/...

Issued at 223 AM EDT Thu Jul 28 2016

ECMWF suggests high pressure building acrs the Great lakes and Nrn
Indiana in the wake of the departing low pressure system...and
have trended toward a dry forecast. However the ECMWF also
suggests ridging along with embedded ridge riding short waves
moving across the middle mississippi river valley and slowly
edging toward Indiana as this long term progresses. Confidence
for precip on Monday will remain low as subsidence remains in
place...but as we progress into Tuesday and Wednesday...warmer and
humid air begins to arrive on southerly flow. Meanwhile...the
ridge riding short waves begin to advect east in to the Ohio
valley. Thus will keep some pops in the forecast during this time
as suggested by superblend.


.AVIATION /Discussion for the 280900z ind taf update/...

VFR condition continue at IND as SHRA and TSRA across southern
Indiana continue to stream east-southeast amid the tropical flow
aloft. For now with cloud cover across the area have removed
diurnal MVFR fog mention....and will continue to trend toward
vcsh/vcts short any shower tho the south that may skirt the TAF

Previous discussion below

/Discussion for 28/0600Z TAF Issuance/...

Issued at 1155 PM EDT Wed Jul 27 2016

Conditions remain at VFR at this time with mainly mid to high clouds
from convection over the Lower Ohio Valley.  Radar showed a lone
-RASH moving into KBMG before rapidly dissipating.

Areas of moisture extends from from the Lower MS Valley northward
into the Ohio Valley. Guidance continues to indicate that weak
boundaries over the Ohio Valley will drift northward overnight into
the morning hours. Challenge is that these boundaries are weak,
making it hard to focus where convection will develop over the next
6-12 hours.  Thus, have gone with mainly VCTS through Thursday
morning over most areas.


.IND Watches/Warnings/Advisories...


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