Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 232245
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
645 PM EDT Fri Jun 23 2017

.UPDATE...
The NEAR TERM Section has been updated below.

&&

.SYNOPSIS...
Issued at 200 PM EDT Fri Jun 23 2017

A Cold front over Central Indiana will push east and exit the
state tonight. Rain will end late this afternoon and evening as
the front passes. High pressure centered over the western plains
states will then build across the Indiana and the Great
Lakes...providing cooler and drier NW flow. This will result in
dry and pleasant weather this weekend...with below normal
temperatures and comfortable humidities.

Dry weather and below normal temperatures will be expected for
much of next week due to the strong high pressure system to the
west.

&&

.NEAR TERM /Tonight/...
Issued at 645 PM EDT Fri Jun 23 2017

Planning on canceling the Flash Flood Watch early as the heavy
rain threat has pushed out of the forecast area. Lingering shower
activity over the southeast zones will probably end around
240100Z.

Previous discussion follows.

Surface analysis shows a Cold front across NW Indiana stretching
to East Central Illinois to SE Missouri. Radar trends show a band
of showers ahead of the front across central Indiana. Some of the
showers continue to produce very heavy rain with the very moist
tropical air mass in place.

GFS and NAM continue to suggest a SE progression of the surface
cold front which will effectively push the stream of moisture SE
and out of Central Indiana. Rapid refresh suggests that by
00Z...only the far southeastern parts of the forecast area will
still be impacted by rain. HRRR progression after that suggests
the forecast area should be rain free by 03Z. Time heights show a
complete loss of forcing and strong drying within the column after
00Z with subsidence. Significant air mass change is also expected
as dew points in the lower 60s and upper 50s...as seen in NRN
Illinois...are set to arrive in the wake of the front.

Thus will trend toward a dry forecast tonight...especially across
the NW where Rain will have ended. May need to keep some pops for
the first 1-2 hours after 00Z across the SE where rain may not
have exited yet. Models suggest strong cold air advection tonight
and will trend lows at or below the expected forecast builder
blend.

&&

.SHORT TERM /Saturday through Monday/...
Issued at 200 PM EDT Fri Jun 23 2017

GFS and NAM suggest a large broad trough in place across the
Great lakes and Ohio valley through Monday. Several weak...poorly
organized disturbances look to pass within the flow...but best
dynamics look to remain well north of Central Indiana. Time
height sections continue to show a dry column through Monday.
Forecast soundings through Monday also show a dry column...but
attainable convective temperatures in the upper 60s to near 70.
However on both Saturday and Sunday afternoons...forecast
soundings show a good mid level inversion that should just result
in some flat topped CU. Furthermore CAPE appears really limited
with values less than 300 J/KG. Thus with dew points in the 50s
and high in the 70s expected for this
period...comfortable...pleasant and not humid weather is expected.
Thus will trend toward Partly cloudy days and Mostly clear nights.

Forecast soundings hint at slightly more CAPE on Monday afternoon
and less of a mid level cap. Forecast blender may try to insert
pops here...however...confidence remains very low at this point
given the NW flow expected and a lack of deep moisture.

&&

.LONG TERM /Monday Night through Friday/...
Issued at 220 AM EDT Thu Jun 22 2017

Next week will generally begin a bit cooler than normal and with a
spotty shower possible as an upper low exits the Great Lakes.
Temperatures will warm gradually, returning to near normal during
the week as upper level flow becomes more zonal and then weakly
anticyclonic by week`s end. A frontal zone will move toward the
region during the latter portion of the week, returning thunderstorm
chances to the area.

Blended initialization handled things well and only minor tweaks
were necessary.

&&

.AVIATION /Discussion for the 240000Z TAFS/...
Issued at 636 PM EDT Fri Jun 23 2017

Lingering shower activity expected to pass off to the southeast of
the terminals by issuance time based on radar loop. Satellite
shows rapid clearing of the lower cloud cover over northwestern
Indiana, so expected most of the cloud cover below 050 to scatter
out during the early evening hours.

Some concern about fog development later tonight given today`s
rainfall, but with drier air advecting in, confidence is low at
this time.

Surface winds 330-350 degrees at 9-12 kts early this evening will
diminish to 5-8 kts after dark and gradually back to 290-310
degrees by sunrise Saturday.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SYNOPSIS...Puma
NEAR TERM...Puma/JAS
SHORT TERM...Puma
LONG TERM...NIELD
AVIATION...JAS



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