920
FXUS63 KIND 081918
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
318 PM EDT Tue Jul 8 2025

.KEY MESSAGES...

- Scattered thunderstorms possible tonight across the western half
of central Indiana.

- More storms possible on Wednesday, with best chances across
southern and eastern Central Indiana.

- Greatest threat for storms in the extended period is Saturday.

&&

.SHORT TERM (This evening through Wednesday)...
Issued at 317 PM EDT Tue Jul 8 2025

Surface analysis early this afternoon shows weak and broad but
poorly defined high pressure was stretching from Arkansas across
Indiana to MI and Ontario. A weak low pressure system was found over
northern WI. GOES16 shows CU Developing across Central Indiana. More
cloud cover was found upstream over IA and MN, near the previously
mentioned low pressure system. Aloft, water vapor imagery shows
subsidence over Indiana but an approaching upper trough over the
northern Mississippi valley contained cloud cover and moisture due
to a thunderstorm complex. Showers and thunderstorms over NRN IL
were continuing to diminish, while storms had developed over
southern IL and western KY.

High pressure over the area is expected to continue to depart this
evening, allowing the development of weak and unorganized southwest
flow ahead of the low over WI and its associated upper trough over
the Mississippi Valley. Subsidence currently remains in place over
Indiana. HRRR shows storm development expected over IL this
afternoon, near a poorly defined cold front, slowly pushing east.
HRRR suggests this precip should reach the Wabash valley shortly
after 00Z, but weaken and dissipate as heating is lost and dry air
and subsidence is encountered aloft. Thus will to to confine best
pops this evening across western parts of the forecast area shortly
after 00Z, but eventually trend toward just a slight pop as the
frontal boundary will still be approaching and entering western
Central Indiana overnight. Skies should remain at least mostly
cloudy overnight as the upper trough arrives in Indiana and residual
mid level clouds linger across the state. Given the expected cloud
cover, lows in the upper 60s will be expected.

Wednesday...

Models suggest the upper trough moving through and exiting the
forecast area through the mid day hours, with subsidence building
into NW Indiana by mid to late afternoon and slowly expanding
southeast.  The weak, poorly defined surface front/trough should
also exit Indiana to the east by late in the day. Time heights show
good lower and mid level moisture available as this forcing is
passing. Forecast soundings show marginal CAPE near 1000-1300 J/KG
through the afternoon, but pwats remain quite high, over 1.90 g/kg,
indicative of a very moist air mass. HRRR shows most of the frontal
tsra development across eastern parts of Central Indiana on
Wednesday morning, while some isolated afternoon showers/storms are
shown to pop up in the wake of the front due to daytime heating
alone. Confidence is low for all of these features, but there is
enough of a signal here that at least some pops will be required.
Best pops will be used across the south and eastern parts of the
forecast area that will likely have the greatest chance to be both
impacted by daytime heating and forcing from the passing upper
trough and surface front. Lesser pops will be used across the rest
of Central Indiana, in the wake of the front, where storm
development should remain rather isolated as diurnal heating will be
the main forcing mechanism amid an unfavorable area for development.

With little temperature advection expected, highs in the mid to
upper 80s will be expected again,

&&

.LONG TERM (Wednesday night through Tuesday)...
Issued at 317 PM EDT Tue Jul 8 2025

A somewhat active weather pattern will develop over the area through
the long term, featuring multiple weak shortwaves and associated
surface features bringing several chances for thunderstorms across
central Indiana.

The first part of the long term will see a few weak shortwaves
embedded within a larger upper trough. This will help to provide
enough lift and moisture for daily chances of showers and
thunderstorms for the end of the week and into the weekend. Best
chances for storms will be during the afternoon to evening hours
each day, thanks to help from diurnal heating. At this time, severe
weather is not expected although isolated heavy rain and brief
strong wind gusts cannot be ruled out. Saturday has the best chance
for more widespread storms, with which has the best chance of
heavier rain and localized flooding within the long term as models
are showing a swath of PWATs in excess of 2" moving through the
region, which is above normal for this time of year.

The influence of high pressure looks to bring a brief break in
precipitation early next week before more troughing and shower/storm
chances arrive at the end of the period.

Temperatures will see highs in the mid to upper 80s most days with
areas across the south potentially seeing near 90 a couple of
days. Overnight lows will be in the 60s to 70s.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 1233 PM EDT Tue Jul 8 2025

Impacts:

- VFR this afternoon and evening.
- Scattered convection possible this evening...mainly at KHUF and
KLAF
- MVFR possible overnight and early Wednesday due to fog.

Discussion:

High pressure over Indiana will exit east this afternoon and
evening.  As max temps are reached today, some diurnal CU is
expected to develop. Convection is expected to re-initiate over IL
this afternoon and attempt to push toward the Wabash early this
evening. However the HRRR suggests that as heating is lost, any
showers or storms will weaken and dissipate before reaching IND or
BMG. For now, we have included a VCSH mention at LAF and HUF as
confidence is low.

Confidence is also low for fog tonight. As the upper trough passes
across Central Indiana mid level clouds is expected overnight, but
surface winds are expected to be light to calm. Clouds may diminish
cooling, however any evening rains would add to residual lower level
moisture. Uncertainty is high on this element, so for now just a
tempo of MVFR fog has been used.

Rain chances may return on Wednesday afternoon as an upper trough
crosses Indiana.


&&

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

$$

SHORT TERM...Puma
LONG TERM...KF
AVIATION...Puma