IND issues Area Forecast Discussion (AFD) at Jul 17, 2:57 PM EDT205
FXUS63 KIND 171857
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
257 PM EDT Fri Jul 17 2026
.KEY MESSAGES...
- Peak heat indices around 100 degrees each afternoon through
Saturday
- Numerous showers and t-storms expected through this evening with
more storms possible late Saturday and late Monday into Tuesday
- Isolated strong to severe thunderstorms are possible Saturday
evening, damaging wind gusts are the primary threat
&&
.DISCUSSION (This evening through Friday)...
Issued at 256 PM EDT Fri Jul 17 2026
This afternoon through Saturday night...
An active pattern is expected with multiple disturbances moving
through the region. The first disturbance is moving through later
today. Modest ascent from the mid-upper level feature combined with
daytime heating of a hot-humid airmass will promote numerous showers
and thunderstorms through the evening. At least moderate
destabilization has occurred this afternoon with steepening lapse
rates.
MLCAPE generally around 2000 to 2500 J/KG and DCAPE values
approaching 600 to 800 J/KG suggest the potential for gusty winds in
thunderstorms. Most thunderstorms will remain sub-severe given weak
deep-layer wind shear and modest DCAPE, but an isolated damaging
wind gust cannot be ruled out. Efficient rainfall rates from warm
rain processes may also result in localized flooding if any training
occurs. Look for convective coverage to quickly decrease around or
shortly after sunset due to the loss of daytime heating. A few
showers or a stray storm cannot be completely ruled out overnight
into Sunday morning with marginal forcing in place.
Additional scattered convection can be expected late Saturday as
another shortwave and associated cold front move in from the north.
Strong destabilization ahead of the approaching cold front along
with modest enhancement of mid-upper level flow could promote
isolated severe thunderstorms, primarily across northern portions of
central Indiana. Forecast soundings depict around 20-30 kt of
effective shear, strong instability with steep low-level lapse
rates, and DCAPE values as high as 1000 to 1300 J/KG which support
the threat. The primary convective hazard is damaging wind gusts.
The severe hail threat will be largely limited by the linear storm
mode. The main timing for severe weather potential is from the late
afternoon through the early overnight hours.
Sunday into next week...
Long range guidance generally depicts upper ridging and weak surface
high pressure building in Sunday behind the departing cold front.
This will provide quiet weather with cooler-drier conditions.
Guidance then suggest another shortwave approaches late Monday into
Tuesday. Exact details remain uncertain with this disturbance due to
diverging model solutions.
Increasing mid-upper level flow atop an unstable airmass late Monday
into Tuesday may support the potential for severe weather, but the
large spread in guidance limits confidence. It is worth noting more
significant cold air advection appears likely with this disturbance
which favors even cooler and drier conditions towards the middle of
next week. Temperatures are expected to cool into the upper 70s to
low 80s while dewpoints fall into the 50s to lower 60s.
&&
.AVIATION (18Z TAF Issuance)...
Issued at 137 PM EDT Fri Jul 17 2026
Impacts:
- Numerous showers and thunderstorms expected through 01Z before
coverage quickly decreases.
- Brief MVFR conditions possible with any heavier showers or
thunderstorms.
Discussion:
Numerous showers and thunderstorms have developed across central
Indiana this afternoon thanks to strong daytime heating of a hot-
humid airmass. Expect this to continue through about 01Z before
convective coverage quickly decreases. Brief MVFR conditions are
possible with any heavier showers or thunderstorms. Predominately
VFR conditions are expected overnight, but patchy ground fog cannot
be ruled out at the outlying TAF sites.
Winds will be light generally from 200-250 degrees sustained at 3-
8KT today with flow closer to 7-13KT Saturday. Infrequent wind gusts
around 17-20 kt are possible on Saturday.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
AVIATION...Melo
DISCUSSION...Melo
Source:
IND issues Area Forecast Discussion (AFD) at Jul 17, 2:57 PM EDT---------------
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