311
FXUS63 KIND 141209
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
809 AM EDT Mon Sep 14 2026

.KEY MESSAGES...

- Cooler and less humid today

- Hot and humid conditions returning Tuesday and lasting
  potentially through late week with highs reaching the 90s

- Periodic thunderstorm chances late Tuesday through the end of the
  week

&&

.FORECAST UPDATE...
Issued at 808 AM EDT Mon Sep 14 2026

No major changes needed to the forecast with conditions generally
evolving as expected. After a chilly start to the morning compared
to recent days, temperatures will rise into the upper 70s to low 80s
today. Model soundings show that RH at the top of the boundary layer
will only be 75-80%, so expect fairly low coverage of diurnal cu
compared to recent days. There could be a few gusts up to 20 mph
across the northern portions of the forecast area, but expect gusts
to remain fairly infrequent.

&&

.DISCUSSION (Today through Sunday)...
Issued at 301 AM EDT Mon Sep 14 2026

A brief break from the warmer weather comes today as high pressure
in tandem with a quick moving upper trough within the band of
westerlies will move into New England by this evening. Upper ridging
will expand back north into the Ohio Valley by Tuesday with a
resumption of hot and humid conditions through midweek along with a
periodic threat for thunderstorms as a frontal boundary becomes
quasi-stationary over the lower Great Lakes. The ridge will persist
over the southeast U S through the weekend with the front drifting
into the area during the second half of the week before retreating
back north. Above normal temperatures will continue for much of the
period with slightly cooler air holding off until early next week.

Today through Wednesday Night

Clear skies early this morning as Canadian high pressure has taken
over across the region. With dewpoints into the 50s and northeast
winds...comfortable temperatures at 06Z ranging from the mid 50s to
the mid 60s.

The presence of the high as it moves east from the Great Lakes into
New England by this evening will produce a brief break from the
warmer weather experienced much of the first half of September so
far. The heat and humidity however will return in earnest as early
as Tuesday with return flow on the back side of the departing high
advecting a hot and humid airmass back into central Indiana through
midweek.

A notable area of deep subsidence will accompany the high pressure
today and pivot across the northeast half of the forecast area. This
will aid in a spectacular day highlighted by sunny skies...much
lower humidity levels and cooler temperatures. Diurnal cu will be
limited to the lower Wabash Valley primarily where afternoon
humidity levels will be subtly higher. As mentioned...this is
temporary with the hot and humid airmass suppressed to the south
drawing back into the area Tuesday as ridging aloft expands into the
Ohio Valley Tuesday.

A cold front will track into the Great Lakes and mid Mississippi
Valley on Tuesday. A broad area of convection will develop this
evening over the upper Midwest aided by a strong low level jet and
accompany the boundary as it drifts south into Tuesday morning.
There does appear to be potential for convection and remnant cloud
debris to make it as far south as the northern Wabash Valley prior
to the weakening of the 850mb flow during the morning hours
otherwise expect much of the day will be dry for the forecast area.
By late day...the remnant outflow boundary from the complex tonight
and early Tuesday may serve as a focus for renewed convection within
a highly unstable airmass across the northern half of the forecast
area. A capping inversion will be present south of Interstate 70
where mainly sunny and hot conditions will persist. Model soundings
show steep lapse rates through 700mb with DCAPE values over 1000
j/kg. A lack of BL shear will keep convection pulsating in intensity
but stronger cells will carry a damaging wind risk that will last
into the evening.

The front will slip into the northern half of the forecast area
Tuesday night and Wednesday with the potential for periodic storms
overnight Tuesday then again Wednesday afternoon and night as subtle
waves aloft ripple through the region. With PWATs in the 1.75 to 2
inch range and ample instability in place...convection will carry a
risk for locally heavy rainfall and gusty winds.

Temps...low level thermals today support highs ranging from the mid
70s northeast to the lower 80s in the lower Wabash Valley with
comfortable humidity levels. Highs will recover into the low and mid
90s Tuesday with heat indices around 100 degrees in the afternoon.
Temperatures for Wednesday are more conditional and are dependent on
convective coverage. Have highs ranging from the upper 80s north to
mid 90s south but if the boundary can make it further south and
there are more clouds and storms...daytime temperatures will end up
lower.

Thursday through Sunday

The Ohio Valley will remain in between the strong upper ridge to the
south and the band of westerlies to the north...resulting in the
frontal boundary retreating back north at the end of the week as
heights aloft rise yet again. Convection will largely be isolated
and diurnally driven both Thursday and Friday. A sharper upper level
wave will track across the northern tier of the country this weekend
suppressing the ridge back to our south. Consequently the front will
be pulled back south into the forecast area as well with an increase
in clouds and scattered convection.

Temperatures will range from the mid 80s to lower 90s for much of
the area Thursday through Saturday falling back into the lower and
mid 80s as the boundary drops into central Indiana on Sunday.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 535 AM EDT Mon Sep 14 2026

Impacts:

- None

Discussion:

Mainly clear skies early this morning with high pressure settles
over the region. An area of mid level clouds moving east through
Illinois should diminish in coverage today as it approaches with a
drier airmass across central Indiana. The high will drift east into
New England through the day with predominant easterly winds at
around 10kts then veer to southeast tonight. Mid and high clouds
will remain scattered at best through early Tuesday.


&&

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

$$

UPDATE...White
AVIATION...Ryan
DISCUSSION...Ryan