Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 222301
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
701 PM EDT FRI JUL 22 2016

.UPDATE...
The AVIATION Section has been updated below.

&&

.SYNOPSIS...
Issued at 355 PM EDT Fri Jul 22 2016

A large ridge over much of the nation will keep a hot and humid
airmass in place across central Indiana through the weekend.
Isolated thunderstorms cannot be ruled out, although most areas
appear likely to be dry through the early portion of the weekend.
A frontal boundary will approach the area later in the weekend
into next week, increasing the thunderstorm chances, primarily
late in the weekend into Monday, and from mid week onward. This
boundary will bring some slight relief from the heat.

&&

.NEAR TERM /Tonight/...
Issued at 355 PM EDT Fri Jul 22 2016

Morning convection over the region significantly stabilized the
atmosphere across the region, although mesoscale analysis
indicates some airmass recovery has occurred over the area this
afternoon.

Cannot rule out an isolated pop up storm tonight but in the
absence of significant upper level support, cannot justify more
than a 15 pop.

Will likely see more significant organized activity far to our
northwest and west, but likely dropping southeast and missing the
area or dissipating before reaching central Indiana as 700 mb
temps remain 10 to 12C.

With little change in airmass, expect similar lows overnight
tonight to last night. Bumped consensus numbers up slightly to
account for this.

&&

.SHORT TERM /Saturday through Monday/...
Issued at 355 PM EDT Fri Jul 22 2016

Will increase pops to 30 Saturday afternoon as there is at least
some chance that remnant circulation or boundaries from prior
convection to our west would be able to spark slightly more
expansive activity across our area, but again with a lack of
substantial upper level support and 700 mb temps remaining 10 to
12C, expect that widespread organized convection is unlikely
through Saturday evening. There is some indication that as the
frontal boundary approaches and the ridge weakens slightly, more
substantial thunderstorm activity could move into the area late
Saturday night into Sunday, followed by the front itself, which
will necessitate increased thunderstorm chances Sunday into
Monday. Significant uncertainty remains, obviously, as this will
depend heavily on how convective activity lays out over the next
24 to 36 hours.

Consensus temperatures appeared reasonable, although did bump them
up slightly, particularly tomorrow when models appear to be
overdoing potential coverage of precip.

Model dewpoints have been slightly too aggressive in recent days
and bumped them down slightly, but this still results in peak heat
indices Saturday and Sunday in excess of 100 across the entire
area, and in excess of 105 in portions of central Indiana. Will
continue heat advisory through Saturday as it currently stands.
May require extension into Sunday, but this will depend
significantly on thunderstorm activity which as previously
mentioned remains highly uncertain.

&&

.LONG TERM /Monday night through Friday/...
Issued at 212 PM EDT Fri Jul 22 2016

Models are in fairly good agreement except for faster return
of rain by the GFS later next week relative to other models.
Will use a blended solution.
1236
A frontal boundary pushing south of the forecast area at the
start of this period brings an end to very warm, humid and
occasionally stormy pattern of recent and upcoming days. High
pressure bridging across the Great Lakes into the Ohio valley
Tuesday and Wednesday will produce more seasonal and dry weather
for most of our area as the front stalls in southern Kentucky.

The next weather system begins approaching Wednesday night or
Thursday depending on model and strength of this system is quite
variable also. All models indicate a return of the front into the
southern Great Lakes on Thursday and a return to more unsettled
wet pattern for 24 to 48 hours. Potential for an inch or two of
rain with this but confidence is very low this far out.

Blended temperature solutions looked pretty comparable to
current forecast and was followed.

&&

.AVIATION /Discussion for 23/0000Z TAF Issuance/...

Issued at 652 PM EDT Fri Jul 22 2016

Running with VFR conditions at this time and should remain so
through 23/02Z this evening. High pressure to our southeast will
be in control overnight and winds should remain very light/calm.
Given that surface dew points are 69-74 deg across much of the
area, temperatures should fall within 1-2 deg of those dew points
which will set up for a widespread fog situation after 23/06Z.

Limited visibilities will result in IFR to MVFR through the
morning hours as heating will dissipate the fog, but low clouds
will be around through mid morning before breaking up for the
afternoon.

&&

.IND Watches/Warnings/Advisories...
Heat Advisory until 8 PM EDT Saturday for INZ021-028>031-035>049-
051>057-060>065-067>072.

&&

$$

SYNOPSIS...NIELD
NEAR TERM...NIELD
SHORT TERM...NIELD
LONG TERM...TUCEK
AVIATION...DWM



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