Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 231412

Area Forecast Discussion
National Weather Service Indianapolis IN
1012 AM EDT Wed Aug 23 2017

The AVIATION Section has been updated below.


Issued at 232 AM EDT Wed Aug 23 2017

High pressure is expected across the area through the weekend. An
upper level low may affect the area by the early part of next


.NEAR TERM /This afternoon/...

Issued at 948 AM EDT Wed Aug 23 2017

Surface analysis late this morning shows broad high pressure in
place over the Plains States...with NW flow spilling into Indiana.
GOES16 shows mainly clear skies across the state with a band of
clouds stretching from the northeast United States to Arkansas and
Texas...leftover front yesterday`s front.

Forecast soundings and Time heights continue to dry air and
subsidence in place across Central Indiana. This is due to the high
pressure in place today to the west...building across Central
Indiana as well as the strong upper ridge in place across the
Western Plains...resulting in lee side subsidence across the
plains...Great Lakes and Ohio Valley.

Forecast soundings suggest a few afternoon CU will be possible as
convective temperatures are reached this afternoon. Thus...partly
Cloudy/Mostly Sunny should work just fine. Given the ongoing Cold
air advection...have trended highs slightly below the forecast
builder blend.


.SHORT TERM /Tonight through Friday night/...
Issued at 232 AM EDT Wed Aug 23 2017

Fairly static upper air pattern expected during this period, as long
wave troughing sets up over the eastern parts of the country. This
will result in a dry northwest upper flow locally. Models suggest
little threat for precipitation as a large surface high drifts
slowly through the region. Will continue with a dry forecast through
Friday night.

Progged low level thicknesses suggest the GFS MOS highs for the next
couple of days are probably a little on the cool side. Will bump the
guidance highs Thursday and Friday. The guidance lows look OK.


.LONG TERM /Saturday through Tuesday/...
Issued at 304 PM EDT Tue Aug 22 2017

Good confidence that the weekend will be dry with below normal
temperatures per the blend as models and ensembles agree that broad
surface high pressure over Ontario and Quebec along with an upper
ridge will result in tranquil weather.

After that, there are differences with the models and ensembles
regarding how far northeast the Harvey revival will get and also
with its associated moisture plume. The 00z ECWMF for instance has
Harvey near the border of northern Texas and northern Louisiana at
00z Tuesday, while the 12z GFS has Harvey absorbed by an upper
Midwest trough and or upper low. The latter will spell more
convection over the area and support high pops by Monday. The former
solution would trend more towards dry Monday, with the upper
Midwest system having less moisture to work with. The blend splits
the difference with small pops Monday. This seems reasonable for
this far out, and after coordinating with IWX and ILN, will not
make any changes. Best pops look to be on Tuesday when the upper
system seems most likely to make an impact at this time anyway.

With increasing clouds, temperatures will have a hard time making it
out of the 70s next week per the blend.


.AVIATION (Discussion for 231500Z TAF update)...

Issued at 1013 AM EDT Wed Aug 23 2017

No ceilings and good visibilities under dry high pressure. Winds
should be 310-340 degrees at 8-11 kts by midday.




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