Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 242322

Area Forecast Discussion
National Weather Service Indianapolis IN
722 PM EDT SUN JUL 24 2016

The AVIATION Section has been updated below.


Issued at 300 PM EDT Sun Jul 24 2016

One more relatively warm and humid day is expected
Monday before slightly cooler and less humid air filters
into our area Tuesday and Wednesday. The change in air mass will
be accompanied by scattered thunderstorms though not all
locations will receive this rain. The next weather system and
return of slightly warmer and humid air will bring a better
rain/storm coverage for the latter half of the week.

Temperatures for this period will start above normal then dip to
seasonal values for the balance of the week.


.NEAR TERM /Tonight/...

Issued at 300 PM EDT Sun Jul 24 2016

Synoptic models have been fairly consistent with the
approaching frontal system and associated timing and coverage
with precipitation. The rapid refresh has been a bit aggressive
with precipitation development for this afternoon relative to
observations perhaps the result of the extreme CAPE values being
observed. Cap appears to be well in place still so will lean
towards slower storm development of synoptic models. Lafayette to
Kokomo area looks to have best shot at getting rain being closest
to approaching front and instability still being relatively high.
Remaining areas rain chances are not as great as stabilizing
cooling occurs and frontal boundary and its lift only slow to
approach northern counties before daybreak.

Guidance minimum temperatures a tad on the warm side the last
few days and will go just below those...but with winds to remain
up a little...minimums should be several degree warmer than this


.SHORT TERM /Monday through Wednesday/...

Issued at 300 PM EDT Sun Jul 24 2016

Models are in fairly good agreement on movement and position
of front over the next several days as high pressure takes over.
The front will move from just north of our area at daybreak
Monday to our southern counties by sundown. With the strongest
wind fields and best upper support well to the north and northeast
convection should be relatively scattered. Where storms do
develop expect heavy rainfall given our fairly high precipitable
water values.

Do not plan to add Heat Advisory for Monday with heat indices
at highest just over 100 in our southern counties. Monday will
still feel relatively warm and humid though. Will keep max temps
near guidance and previous forecast. Rain chances will likely
follow diurnal trend with better chances at peak heating and
along and ahead of southeast advancing cold front. Again given
best dynamics being well northeast would expect no more than
scattered convection and pops still in the chance category.

For Tuesday and Wednesday the frontal boundary will slip south
of the Ohio River. Current forecast of rain chances in
southern counties may be a bit pessimistic as high pressure may
more likely drive rain chances south of the Ohio River. Will keep
low chances for now but another model run may suggest their

Temperatures Tuesday and Wednesday still look fairly good with
mid and upper 80s appearing reasonable. Might be a tad high on
holding southern county dewpoints in the lower 70s. High pressure
scouring out the tropical air may reach south of our area by
Wednesday and may need future adjusting.


.LONG TERM /Wednesday night through Sunday/...

Issued at 218 PM EDT Sun Jul 24 2016

Main challenge for the long term will be timing various upper waves
moving through and ahead of a mean Mississippi Valley trough.
Judging by the differences in the operational GFS and ECMWF and
individual ensemble spaghetti plot members, the confidence in
strength and timing of these waves is not good. For instance, the
00z and 12z GFS runs have a strong wave moving through Thursday
night, while the 00z ECMWF version is much weaker.  Thus, will
accept regional blend, which has chance pops Wednesday night through

Low level thermal progs support normal to slightly below normal
blend highs in the lower to mid 80s. Meanwhile, look for overnight
lows mostly be in the mid to upper 60s.


.AVIATION /Discussion for 250000Z TAF Issuance/...
Issued at 722 PM EDT Sun Jul 24 2016

Restrictions possible within convection overnight and Monday
otherwise predominantly VFR conditions expected.

Convection has been slow to develop but has finally started to
become better organized over northern Illinois since 22Z.
Convection developing in the vicinity of a prefrontal trough
and aligned with an axis of strong instability with MLCAPEs in
excess of 5000 J/KG. Central Indiana remains under the influence
of the ridge aloft and effectively capped with 700mb temps around

That presents the question of how far south the northern Illinois
convection comes over the next 6-8 hours as storms move against
the ridge flank. It has been another difficult day for model
guidance...most of which has been grossly overdoing the convective
development to the northwest. The parallel HRRR has the most
reasonable solution at this point and loosely utilized it for
timing and southward extent to convection into the overnight. The
only terminal with medium to high confidence in convective impacts
at this point is KLAF with the potential that KHUF and KIND are
also impacted after midnight. Introduce VCTS at KLAF at 02Z with
more specific impacts in the 05-10Z period. Will maintain a VCTS
mention only at both KHUF and KIND until a better determination
can be made regarding whether storms will directly impact either
site late tonight as airmass quickly becomes less favorable for
convection to persist further south.

Storms are likely to diminish in coverage and intensity overnight
as instability is lost...then refire by Monday afternoon south of
I-70 along and ahead of the cold front in the moist unstable
airmass. Will focus VCTS after 17-18Z at KBMG and KHUF and may
eventually need to include KIND as well. Drier air will advect in
from the north by Monday evening.


.IND Watches/Warnings/Advisories...
Heat Advisory until 8 PM EDT this evening for INZ021-028>031-



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