610
FXUS63 KIND 132147
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
547 PM EDT Sun Sep 13 2026

.KEY MESSAGES...

- Partly Cloudy this evening, Mostly Clear overnight.

- Cooler and less humid on Monday

- Hot and humid conditions returning Tuesday and Wednesday with
  highs reaching the 90s

&&

.DISCUSSION (This evening through Sunday)...
Issued at 134 PM EDT Sun Sep 13 2026

Overview.

A weak frontal boundary moving across Central Indiana will bring a
brief chance of showers late this afternoon and early evening before
high pressure brings cooler and less humid air on Monday. Hot and
humid conditions will return quickly on Tuesday and Wednesday as an
upper-level ridge builds across the Ohio Valley, driving high
temperatures into the lower 90s. Occasional showers and storms are
expected late Tuesday through the weekend with best chances Tuesday
night and again on Thursday.

Tonight Through Tuesday.

The aforementioned surface cold front will drift through Central
Indiana this evening and will exit to the southeast during the
overnight hours. HREF guidance and HRRR show isolated to scattered
showers along the baroclinic zone through sunset, diminishing
rapidly as surface heating is lost and mid-level PVA departs.
Moderate CAA in the 925-850mb layer behind the front will push lower
dewpoint air across the region, while surface high pressure
expanding from the Upper Midwest builds into the Ohio Valley.
Efficient radiational cooling under clearing skies will drop Sunday
night lows into the 50s across most locations. There may be some
fog/low stratus across the Upper Wabash Valley but with the much
drier air, confidence is low.

Surface high pressure across the region on Monday will result in
broad-scale subsidence, light northerly flow, and pleasantly cool
conditions. Model sounding profiles show a dry tropospheric column
with low-level thermal mixing supporting daytime highs ranging from
the mid 70s northeast to the lower 80s in the lower Wabash Valley.
As the high shifts toward New England Monday night, return low-level
southerly flow will initiate rapid moisture advection aloft. Mid-
level height rises driven by an expanding 500mb ridge over the
Tennessee Valley will take hold by Tuesday. Strong thermal advection
at 850mb will lift daytime maximum temperatures into the upper 80s
to lower 90s on Tuesday, while dewpoints rise back into the upper
60s.

Wednesday Through Sunday.

The synoptic pattern on Wednesday features a strong mid-level
ridging over the southeastern states and Tennessee Valley, holding
low-level baroclinicity and main storm tracks north over the Great
Lakes. Continued S/SW surface flow and low-level WAA will maintain
hot and muggy conditions across Central Indiana, with highs in the
lower to mid 90s. There are some signs that a frontal system Tuesday
night may sag south into central Indiana, but with the strength of
the aforementioned ridge, confidence is fairly low as to how far
south the front and associated rain threats will go. While diurnal
MUCAPE values may exceed 1500 J/kg, weak mid-level capping and
background subsidence will keep convective risks isolated and
unorganized through Wednesday afternoon.

The next best chance for rain arrives late Wednesday night into
Thursday as models show an upper trough ejecting out of the Plains
toward the Upper Mississippi Valley. An advancing surface cold front
will interact with an intensifying 40-50 kt 850mb LLJ, driving a
deep plume of moisture northward with PWAT values surpassing 1.6 to
1.8 inches. Scattered showers and the potential for more organized
thunderstorm clusters are likely at times Thursday into Friday along
and ahead of the frontal boundary. Diurnal timing and cloud cover
will determine peak instability, though shear profiles remain
sufficient to support convective organization. As the front slowly
pushes south by Sunday, post-frontal CAA and building surface high
pressure to the north will lower high temperatures into the upper
70s to low 80s.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 546 PM EDT Sun Sep 13 2026

Impacts:

- VFR this TAF period

Discussion:

Post frontal high cloud from northern Indiana to central IL will
push across the TAf sites this evening providing high VFR Cigs.

On Monday, forecast soundings show a dry column with unreachable
convective temperatures as strong surface high pressure moves
through Indiana and Ohio due to strong ridging aloft. Some
high, passing CI will be possible through the day.

&&

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

$$

AVIATION...Puma
DISCUSSION...White