816
FXUS63 KIND 261941
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
341 PM EDT Sun Jul 26 2026

.KEY MESSAGES...

- Hot and humid conditions through Monday

- One or more thunderstorm complexes possible tonight into Monday
  night, with damaging winds and heavy rainfall the primary
  threats, though uncertainty on exact details remains high

- Temperatures nearer normal and less humid mid week

&&

.DISCUSSION (This evening through Sunday)...
Issued at 340 PM EDT Sun Jul 26 2026

This Afternoon into Monday Night...

A highly uncertain forecast scenario remains the case again today,
particularly with respect to the severe thunderstorm threat from
late today into Monday night, with multiple scenarios on the table.
As is often the case with these depth of the warm season setups, the
exact evolution of each convective round will be largely
thermodynamically driven and heavily influenced by the prior rounds,
resulting in low confidence in the exact details as time goes on.

A volatile airmass is in place this afternoon to our southwest
across the mid Mississippi and far lower Ohio Valleys, along and
west of a frontal zone, characterized by temperatures in the mid 80s
to mid 90s and dewpoints as high as the low 80s, resulting in MLCAPE
values near 5000 J/kg, along with modest to strong effective shear
values of 25-40KT overlapping. This should promote thunderstorm
development late this afternoon into this evening as a subtle upper
level disturbance slides southeast along the periphery of the upper
level ridge, and this activity may nudge into the southwestern
portions of the forecast area this evening. Will stick with chance
PoPs for now, as it is unclear how far east this activity will make
it, as the instability gradient will likely result in storm motion
with a largely southerly component, and substantial convective
inhibition remains across central Indiana on the milder side of the
cloud-reinforced differential heating frontal boundary.

Additional severe convection is likely to develop over the upper
Midwest, and this activity could make it into central Indiana as
early as the pre-dawn hours Monday, though the unfavorable diurnal
timing may limit the severe threat should this come to pass. With
both of these possible rounds of thunderstorms, damaging winds would
be the primary concern.

Another round of convection appears likely to initiate somewhere
over the upper Great Lakes tomorrow afternoon associated with an
upper level shortwave and surface cold front, again likely dropping
southerly along an instability gradient in a continued volatile
airmass characterized by ample shear and instability, along with
precipitable water values at times in the vicinity of 2 inches. This
will present again a primarily damaging wind threat, though an
isolated tornado cannot be ruled out. Additionally, the
aforementioned moist airmass along with deep warm rain processes as
the wet bulb zero height remains seasonably high will present a
heavy rainfall and localized flash flood threat, limited by the
relatively progressive nature of any thunderstorm complexes - but a
fairly strong westerly low level jet ahead of the cold front could
produce some regeneration/training potential on the western flank of
any MCS depending upon cold pool orientation.

Temperatures will have the potential to soar well into the 80s or
low 90s on Monday afternoon, though this, too, is uncertain as any
early day convective debris cloudiness could limit the impact of
warm advection and insolation - the more sun, the greater the
potential for highs getting to the 90 degree mark, which may couple
with dewpoints well into the 70s to produce heat index values at or
above 100 degrees Monday afternoon.

Tuesday onward...

Cold frontal passage Monday night into early Tuesday will bring
temperatures back down much closer to seasonal normals from mid week
onward, with a largely dry forecast until very late in the week as
surface high pressure dominates the area. As the ridge aloft
retrogrades slightly and the overall pattern amplifies, upper level
disturbances late in the week may promote rain chances, though
significant disagreement on these systems precludes more than a
slight chance to low chance PoP in any one period from Friday into
the weekend.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 129 PM EDT Sun Jul 26 2026

Impacts:

- Lingering MVFR ceilings at HUF early

- MVFR fog possible overnight

- Chance of thunderstorms near daybreak into the morning hours Monday

Discussion:

Low clouds have gradually scattered out in many places this morning,
but MVFR ceilings linger at HUF. VFR should return there in the next
few hours.

With plentiful low level moisture and light to calm winds overnight,
expect fog development again, though not quite to the same degree as
this morning, with mid and high cloud working against radiational
cooling. Will take the outlying sites down to 3-4SM.

There is a highly conditional thunderstorm threat late tonight into
the morning hours Monday, and will carry PROB30 at all sites for a 4
hour or so period somewhere in the 09-15Z time frame depending on
the site. Confidence in this is low, but any storms that do impact
the area will have the potential to be strong, so wanted a mention
of some kind in.

Winds will be fairly light and frequently variable through the
period.

&&

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

&&

$$

AVIATION...Nield
DISCUSSION...Nield