Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 212347

Area Forecast Discussion
National Weather Service Indianapolis IN
747 PM EDT Fri Jul 21 2017

The AVIATION Section has been updated below.


Issued at 332 PM EDT Fri Jul 21 2017

Central Indiana will remain on the edge of a strong upper ridge into
Saturday.  This will maintain hot and exceptionally humid
conditions...along with threat for clusters of thunderstorms to
impact the region...especially north tonight and Saturday.
A Cold front will move south across Indiana Saturday night and
early Sunday.

Slightly cooler and drier weather will be the rule early next week
as high pressure behind the cold front moves east across our region.

frontal boundary will shift south of the area
by early Sunday with drier and slightly cooler air spreading into
the region for the second half of the weekend. High pressure will
bring mainly dry weather with seasonable temperatures beginning
early next week.

An area of low pressure approaching from the west will produce a
chance of more showers and Thunderstorms Thursday and Friday.


.NEAR TERM /Tonight/...
Issued at 332 PM EDT Fri Jul 21 2017

Mostly quiet but hot weather was the rule early this afternoon.
Radar at 19Z indicated one small thunderstorm over west central
Indiana and the high resolution indicated isolated thunderstorms are
possible over western and southern sections this afternoon.   An
area of showers was also located just east of Kokomo.

A strong upper ridge was over the south central U.S....while a
stationary front extended from extreme northern Indiana west across
southern Iowa to Nebraska.   Models indicate a very unstable airmass
south of the front and with low level convergence along the
front...especially to our west.  Thunderstorms will increase over
Iowa and northwest Illinois next several hours and will likely
spread east toward northern Indiana by late evening.
SPC has our northwest sections in an enhanced risk of severe weather
later tonight.

Will mention slight chance POPS most areas this evening...increasing
to likely POPS near or shortly after midnight across our northwest
with stronger thunderstorms spread east across our northern sections
late tonight.

An isolated thunderstorm may linger into our south early this
evening per high res model.  Otherwise it should be dry there later
Lows tonight will be in the middle 70s with some lower 70s in a few


.SHORT TERM /Saturday through Monday/...
Issued at 332 PM EDT Fri Jul 21 2017

Forecast challenges focus on precip chances mainly Saturday and
Saturday night and also with...excessive heat and humidity south.

An area of low pressure over the upper midwest will move east across
northern Indiana and the southern great lakes Saturday and a cold
front will move south across our region Saturday night and early

Scattered thunderstorms will be the rule over northern sections...
while hot humid and mostly dry conditions will occur south with the
air mass more capped there.

The combination of highs in the middle 90s and high humidities will
produce heat index values from 105 to 109 across our south and will
continue heat advisories along and south of a Terre Haute to North
Vernon line through Saturday.

Expect our best chance of thunderstorms to be Saturday evening and
raised POPS some area then.

The cold front will move south into Kentucky Monday as weak high
pressure builds into the great lakes.   This will allow for mostly
dry and slightly cooler weather Sunday into Monday.  In most cases
stayed close to a MOS blend on temperatures.


.LONG TERM /Monday night through Friday/...

Issued at 237 PM EDT Fri Jul 21 2017

The long term starts out dry with high pressure over the area, and
confidence in this dry period is moderate. Lower confidence for the
low chance pops that arrive Wednesday, with general model
disagreement on any sort of upper wave making it into the area.
Higher chances for showers and thunderstorms arrive Thursday and
Friday with a front that could stall out as an upper ridge over the
area buckles. Temperatures in the mid 80s expected Tuesday with mid
to upper 80s Wednesday. Thursday and Friday lower confidence in
temperatures due to rain/storm chances, but thicknesses suggest
generally mid to upper 80s.


.AVIATION /Discussion for the 22/0000Z TAF Issuance/...

Issued at 733 PM EDT Fri Jul 21 2017

Scattered showers and thunderstorms will be possible throughout
the TAF period, but conditions will generally be at VFR levels.
The exception will be any reduced visibilities and ceilings that
could occur with any storms that do form. Winds will generally be
south/southwesterly at 8 to 12 kts.


Heat Advisory until 7 PM EDT Saturday for INZ051>053-060>062-



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