Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 191843

Area Forecast Discussion
National Weather Service Indianapolis IN
242 PM EDT Thu Oct 19 2017

.UPDATE...Long Term section has been updated below.


Issued at 220 PM EDT Thu Oct 19 2017

High pressure will provide dry and warm weather through Saturday.
Then, a pair of low pressure systems will bring wet weather to
central Indiana late weekend and into next week. The second cold
frontal passage will bring much cooler weather to the area by next


.NEAR TERM /Tonight/...

Issued at 220 PM EDT Thu Oct 19 2017

An upper ridge will build over the area tonight as surface high
pressure expands from the southern states to the eastern Great
Lakes. Model time sections were showing a very dry column except at
the upper levels of the atmosphere. Thus, good confidence there will
no more than some passing cirrus and overnight lows in the upper 40s
to lower 50s per the blend.


.SHORT TERM /Friday through Sunday/...

Issued at 220 PM EDT Thu Oct 19 2017

High confidence in warm and dry weather through Saturday as surface
high pressure moves slowly eastward across the eastern states. Then,
a change is in store as a frontal system is expected to move just
west of central Indiana Sunday afternoon. The 12z ECMWF has now
caught up with the faster 12z GFS. They both bring the cold front to
near a Rockford to St. Louis line by 12z Sunday. The deepest
moisture and best lift both arrive Sunday per similar model output.
That supports the likely to categorical blend pops on Sunday.
Meanwhile, blend small pops west overnight Saturday night look
reasonable as well. Confidence in overall trend is high if not exact
timing. Also, good confidence in temperature trends with above
average highs in the lower and middle 70s through Sunday.

Models were hinting there could be some weak elevated instability
over parts of the area Saturday night and Sunday. However, at this
time, feel the limited instability is not enough to mention thunder.


.LONG TERM /Sunday Night through Thursday/...
Issued at 242 PM EDT Thu Oct 19 2017

The long term period will be wet through middle of next week and
turning much cooler.

Models move a high amplitude upper trough slowly east across the
area during the long term.   These actually start out two separate being an upper disturbance over the lower Mississippi
valley and a stronger upper low over central Canada.  Models tend to
merge these systems over time as the upper low over Canada digs
towards the great lakes and the southern system being absorbed by
the northern system as it moves to the northeast.

Models are in general agreement...but there are timing differences
with the southern system as the GFS and Canadian are a little faster
with the southern system and are not as wet Monday on.  The Euro on
the other hand is quite wet and slow with the southern system.
Because of uncertainty...will go with a model blend for now with
chance of showers through the middle of next week and then dry by

Temperatures will become progressively cooler through the middle of
next week with highs in the upper 50s to lower 60s by Tuesday and
the lower to middle 50s by Wednesday.  Overall superblend
temperatures seem reasonable and only a few minor tweaks were made.


.AVIATION /Discussion for 19/18Z TAF Issuance/...

Issued at 1245 PM EDT Thu Oct 19 2017

VFR conditions expected through the TAF period.

High pressure will remain in place through the period with clear
skies expected. Isolated patchy fog may be present tomorrow
morning across eastern and southern Indiana, but should stay clear
of the terminals. Winds will generally be southwesterly at 6-8




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