527
FXUS63 KIND 190730
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
330 AM EDT Thu Jun 19 2025

.KEY MESSAGES...

- A few lingering showers and storms possible today, areas of fog
  possible tonight

- Hottest conditions of the season thus far expected this weekend
  into next week, with significant potential for impactful heat and
  humidity

&&

.SHORT TERM (Today and tonight)...
Issued at 330 AM EDT Thu Jun 19 2025

A much quieter, though not entirely quiet, weather day is
anticipated across central Indiana Thursday.

With the front still in the region early this morning and a weak
secondary upper level impulse still to pass through the area, some
lingering showers and perhaps a storm or two can be expected, with
chances highest in the east and northeast through the day, gradually
tapering off to isolated by this afternoon, as, while upright
instability will be present, increasing large scale subsidence as
the wave axis passes will help to keep coverage down.

Any lingering precipitation should come to an end by 00Z, with dry
and mostly clear skies setting up a good radiational cooling
situation in the setting of fairly damp soils and dewpoints that,
while slightly lower, are not expected to decrease significantly.
This should allow for some areas of fog to develop, perhaps dense in
spots, particularly in climatologically favored areas.

Temperatures today and tonight will be milder, topping out in the
mid 70s to mid 80s across the area, and dropping to near dewpoints
in the mid 60s tonight, though this reprieve will be relatively
short lived.

&&

.LONG TERM (Friday through Wednesday)...
Issued at 330 AM EDT Thu Jun 19 2025

...HOTTEST CONDITIONS OF THE YOUNG SEASON THUS FAR UPCOMING...

The primary focus of the long term will be on the upcoming hot and
humid conditions this weekend into next week.

A strong subtropical ridge of high pressure aloft (595-597 dam at
500 mb) will build over the Ohio Valley/east central CONUS this
weekend into next week, though some guidance suggests a slight
retrogression of this ridge to the southwest mid week next week,
which could put the area in line to experience thunderstorms at
times in the hot and humid airmass that remains in place on the
periphery of the ridge, particularly as a frontal boundary stalls
along the periphery and sparks potential ridge-riding convective
complexes. This potential will necessitate at least low to middling
chances for thunderstorms at times from Tuesday onward.

Strong subsidence aloft and an associated capping inversion should
prevent any thunderstorms despite the hot and humid conditions
through the weekend into Monday, though an isolated buildup would
not be shocking near peak heating - mainly Monday as the subsidence
inversion weakens.

Temperatures will likely climb into the 90s each day across most if
not all of central Indiana from Saturday into Wednesday, with peak
afternoon heat index values near or above 100 degrees, perhaps
approaching 105 degrees in spots. Heat headlines may well be on the
table at some point this coming weekend - but regardless, we are
looking at the first prolonged heat spell of the young summer season
for central Indiana, with overnight lows in the low to mid 70s
providing only minimal relief in the humid airmass, especially for
those without access to air conditioning.

Experimental NWS HeatRisk values suggest potential for major or
extreme (level 3/4 on a scale of 0-4) heat-related impacts for much
or all of central Indiana each day from Sunday onward as cumulative
heat stress builds, though possible convective activity mid week
could act to alleviate this somewhat. Nonetheless, those with
outdoor plans for the coming weekend into next week, or without
access to adequate cooling and/or vulnerability to heat illness
should pay close attention to the forecast and be prepared to take
action as necessary.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 123 AM EDT Thu Jun 19 2025

Impacts:

- MVFR ceilings (IFR at LAF) expected later tonight into Thursday
  late morning/midday

- A few showers or storms early in the period at a few sites

- Wind gusts in the 15-20KT range Thursday afternoon from 280-300
  degrees

Discussion:

As an upper trough passes through the region overnight, a few
lingering showers or storms may impact some of the sites early in
the period, followed by widespread MVFR ceilings (IFR likely at
LAF). The ceiling restrictions will last through late morning/midday
before VFR returns at all sites.

During the afternoon hours Thursday, west/northwesterly wind gusts
can be expected at times in the 15-20KT range. These gusts will
subside in the late afternoon/evening in typical diurnal fashion.

Light winds and mostly clear skies are expected tomorrow night
across the area. This may allow for some patchy fog formation given
good radiational cooling conditions, though this is far too
uncertain for inclusion at this time.

&&

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

&&

$$

SHORT TERM...Nield
LONG TERM...Nield
AVIATION...Nield