Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 271704

Area Forecast Discussion
National Weather Service Indianapolis IN
104 PM EDT WED JUL 27 2016

The AVIATION Section has been updated below.


Issued at 358 AM EDT Wed Jul 27 2016

An active weather pattern continues with a frontal boundary
meandering around the area and interacting with upper waves
bringing thunderstorm chances throughout the forecast period. With
mainly upper troughing over the area temperatures after today will
be near normal to slightly below normal.


.NEAR TERM /Today/...

Issued at 358 AM EDT Wed Jul 27 2016

Main convergence area appears to be near the southern border of the
forecast area at this time. Expect this to surge a little further
south today with high pressure to the north building in, and thus
think best chances for rain and storms will be south of the
area.However, while hi res models have been alternately pushing
precip into the southern counties and then out of them with
each subsequent run, the 6z RAP and HRRR both bring precip into
the southern counties, and the HRRR even comes as far north as I-
70.Favor the southern solutions given the current boundary
location but can`t ignore latest runs so will maintain slight to
low chance pops along the southern border. Given the heavy rain in
the southeastern counties yesterday, will need to monitor any
development in that area especially with the ample moisture and
near saturated deep layer soundings.


.SHORT TERM /Tonight through Friday night/...

Issued at 358 AM EDT Wed Jul 27 2016

Tonight an upper wave will arrive to interact with the front again
and bring more thunderstorm chances to the area. Models are showing
some variability on where the front will be and thus the axis of
highest pops and heaviest rainfall are tough to pinpoint. With the
addition of the upper forcing will go at least chance pops
everywhere and may put likelies in where models overlap. Thursday
looks like the best forcing and most widespread precip chances in
the forecast, with a front moving through the area and another
shortwave to work with. Will then need to continue to carry chance
pops Thursday night through Friday night with the front somewhere in
the vicinity but less confidence on timing of shortwaves and whether
the front will be over the forecast area or just north or south of
it. Given the uncertainty, can`t justify any flood headlines at this
point, but will need to monitor trends with subsequent issuance to
see if model consensus develops on location of heavy rain axis
given the ample available moisture.

For temperatures will use a consensus approach, with the knowledge
that should widespread precip/cloud cover last through the day
Thursday or Friday highs will be a decent bit lower. With more
confidence on precip Thursday lowered highs a bit from consensus


.LONG TERM /Saturday through Tuesday/...

Issued at 238 AM EDT Wed Jul 27 2016

ECMWF suggests a lingering frontal boundary will be found across
the southern parts of Central Indiana on Saturday while a broad
weak trough lies aloft. Confidence remains low for a precip
event...however given these features have included pops through
Sunday as they pass. This is what superblend suggests.

On Monday and Tuesday...ridging aloft and High pressure across
Central Indiana is suggested by the ECMWF...however superblend
continue to carry pops. Given the expected subsidence beneath a
ridge and large...broad high pressure in place across the eastern
United States...have trended pops dry. Temps look to remain near
seasonal normals.


.AVIATION /Discussion for 271800z TAFs/...

Issued at 102 PM EDT Wed Jul 27 2016

Winds will be light and variable through the forecast with a
diffuse frontal boundary in the area. Mainly VFR conditions are
expected during this TAF period though potential IFR fog and
ceilings could develop at KBMG and KHUF after 280600z.

The TAF sites are still in a moist tropical flow aloft.
Surface pressure gradients are weak and thus the light and
variable wind direction. Model soundings still show a mid level
inversion across the area which will impede significant
convection from occurring.

Light wind and mid cloud passing overhead at times tonight
may lead to some localized fog toward daybreak.

Models lift a weak surface low into the lower Ohio Valley
by daybreak and this will lift scattered light showers back
towards all sites except KLAF. Eventually this low rain threat
will also spread toward KLAF by 281400z.


.IND Watches/Warnings/Advisories...


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