427
FXUS63 KIND 260933
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
533 AM EDT Fri Jun 26 2026

.KEY MESSAGES...

- Flood Watch through Saturday morning for southern portions of
  central Indiana with 1 to 3 inches of rain possible

- Multiple rounds of showers and storms producing torrential
  rainfall and localized flooding expected through Saturday night

- Isolated severe storms possible across south central Indiana this
  afternoon and evening

- Hot and humid conditions expected for much of next week with
  multiple days in the 90s and heat indices over 100 degrees

&&

.DISCUSSION (Today through Thursday)...
Issued at 255 AM EDT Fri Jun 26 2026

Convection continues to develop in advance of a mid level wave over
the mid Mississippi Valley this morning...expanding east across
southern Illinois and into the lower Wabash Valley. Embedded cells
are dumping in excess of an inch an hour in spots but at least to
this point at 06Z...the heaviest totals have remained just south of
the forecast area. Temperatures ranged from the mid 60s to the
lower 70s.

Quasi-zonal flow aloft in tandem with a stagnant frontal boundary
over the Ohio Valley will provide for multiple opportunities for
showers and storms through Saturday night. Storms will carry a
renewed concern for flooding later today into tonight as a surface
wave rides along the boundary and across the region. The front will
be forced north of the region by Sunday with the upper level regime
transitioning to a broad ridge over the Mississippi and Ohio
Valleys. This will resulting in an extended period of hot and humid
weather through next week likely resulting in the hottest days of
the summer to date.

Today through Saturday Night

The ongoing convection from southeast Missouri northeast into
southwest Indiana should continue to expand over the next several
hours in response to stronger 850mb flow nosing into the Ohio
Valley. The presence of a southwesterly component to the low level
flow supports potential backbuilding of convection and training
cells through daybreak that will carry a short term flood threat
focused especially across the lower Wabash Valley. PWATs will
gradually nudge up as well in response to a surge in moisture
advection into the area from the southwest. Showers will expand
northeast across the forecast area from just before daybreak through
much of the morning.

Coverage and intensity of convection will tick up into the afternoon
as a surface wave approaches from the west. A remnant MCV associated
with the convective cluster over eastern Kansas early this morning
will move into the Ohio Valley by the afternoon. This feature
presents a wild card introducing a conditional severe weather risk
in addition to the flooding concerns for several hours later today
focused over southern portions of the forecast area. An increase in
low level shear and helicity within the lowest 1 to 2km could be
sufficient in concert with weak instability up to around 1000 j/kg
to carry a threat for damaging winds and a few tornadoes within
stronger cells by late day. The tropical nature of the airmass
highlighted by a deeply saturated column...dewpoints in the lower
70s and LCLs below 1000m also offers some historical context locally
with the MCV in the area to create potential mischief for cells to
rotate in the near surface layer. That being said...the expected
thick stratus into the afternoon will serve as a limiting factor to
convective intensity. At this time...greatest concern would be from
mid afternoon into the early evening across far southern portions of
the forecast area south into Kentucky...with higher impacts very
likely south of the forecast area where better surface heating will
be present.

The heavy rainfall and potential for flooding remains the primary
concern for later today however. Gradual strengthening of the low
level jet in advance of the surface wave will continue to pump a
rich fetch of moisture into the region with PWATS rising above 2
inches over southern counties by mid afternoon. This along with
freezing level rising to near 15kft are suggestive of warm rain
processes and highly efficient rainfall from convection into the
early evening as the low passes through. Am becoming concerned
though that the flood threat will not be over once the low passes as
CAMs are starting to pick up on renewed convective development over
the southern half of the area into the overnight along the remnant
frontal boundary. Strengthening of the low level jet oriented to the
west-southwest tonight increases the potential for backbuilding and
training of convection in the vicinity of the boundary before
shifting south closer to the Ohio River by daybreak Saturday.

With the trends noted above and considering the recent wet
conditions across the southern portions of the forecast area...have
extended the Flood Watch east to encompass the rest of the southern
third of the forecast area. High confidence exists in a widespread 1
to 3 inches with locally higher amounts across the Watch area by
Saturday morning.

The convective focus is likely to shift closer to the Ohio River
initially on Saturday as the boundary drifts in that direction but
it will start to pull back north later in the day as ridging aloft
amplifies to our west. This will unfortunately pull convection back
into the waterlogged portions of the southern forecast area Saturday
afternoon and evening and could renew flooding concerns. In
addition...a subtle wave traversing overtop of the expanding ridge
may generate a convective cluster diving southeast into parts of the
area Saturday night. This may require an extension in time to the
Flood Watch that will be revisited later today or tonight.

Sunday into Next Week

A few storms may linger Sunday morning but the trend will be for the
frontal boundary to lift north of the area Sunday as deep ridging
expands into the Ohio Valley. This will serve as the transition
point towards progressively hotter and more humid conditions that
will last through much of next week as the core of the ridge peaks
with heights at 596-597dam. Multiple days with highs in the 90s are
anticipated with the highest heat indices of the summer so far
rising into the 100s during the afternoons. Isolated late afternoon
and evening convection may develop by late next week as the mid
level heights begin to fall back. As the upper ridge retrogrades
back to the southwest next weekend...will need to monitor for an
increased risk for convective clusters riding along the periphery of
the ridge impacting parts of the region.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 533 AM EDT Fri Jun 26 2026

Impacts:

- Rain spreading across the area this morning

- Numerous showers throughout the day and tonight with thunder
  possible as well this afternoon and early evening

- Poor flying conditions developing by early afternoon and
  persisting through Saturday morning

Discussion:

Showers continue to expand northeast across central Indiana early
this morning. This first wave of rain will pass across the terminals
over the next few hours and may be followed by a brief lull in
shower coverage later this morning. The approach of a surface wave
as a frontal boundary oscillates across the area will bring numerous
showers and scattered thunderstorms this afternoon and evening with
the potential for IFR and lower visibilities briefly within any
convection that impacts the terminals. Showers should become more
scattered in coverage late tonight as the front lingers over central
Indiana in the wake of the surface low moving away to the east.

Ceilings will gradually lower to MVFR levels by midday then settle
at IFR and lower later this afternoon into tonight. Light and
variable winds early this morning will largely transition to E/SE
for much of the day with the possibility of more chaotic wind
directions this evening as the low passes through the area.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Saturday morning for INZ051>053-060>065-
067>072.

&&

$$

AVIATION...Ryan
DISCUSSION...Ryan