008
FXUS63 KIND 270516
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
116 AM EDT Fri Jun 27 2025

.KEY MESSAGES...

- *HEAT ADVISORY* continues through late day Friday

- Heat indices up to 100-107 degrees and low temperatures near or
  above 74 degrees through Friday

- Scattered daily afternoon showers/t-storms, isolated strong to
  severe wind gusts are possible as well as localized flooding

&&

.FORECAST UPDATE...
Issued at 958 PM EDT Thu Jun 26 2025

Subsidence behind convection earlier today kept central Indiana
quiet for a while, but as this limiting factor moved off, pop up
convection returned to the area. A few of these are lingering across
the area, but with the loss of heating, these should dissipate soon.

Extended the isolated shower and storm mention for a bit this
evening, but expect the remainder of the night to be quiet.

Cirrus from this convection as well as previous convection will
gradually thin, but skies will average out partly cloudy for much of
the area.

Adjusted hourly temperatures as needed, but overall the forecast low
temperatures look good with only a few tweaks needed.

&&

.SHORT TERM (This evening through Friday)...
Issued at 254 PM EDT Thu Jun 26 2025

Showers and thunderstorms have developed today, largely from Indy
eastward. Cumulus developed initially across the entire area fairly
evenly...but over time only the eastern half grew into storms. The
western half, however, has diminished in coverage and height.
Low-level water vapor reveals a pocket of dry air located over the
western portion of the CWA. What likely happened is that cumulus
fired up upon reaching convective temps...but as the boundary
layer deepened, some of that dry air mixed down allowing
convective processes to diminish over our western counties.

Convection is therefore likely to be confined mainly to the eastern
portions of the area. Some of the storms have strengthened nicely,
with a few weak downburst signatures shown on the KIND radar.
Storm activity may continue to pose a downburst threat as it
travels east into Ohio. Steep low-level lapse rates and decent
storm top flow support this idea. Shower and storm activity should
rapidly diminish after sunset as diurnal heating is lost.

Showers and thunderstorms return on Friday as a weak cold front
approaches the area. Model soundings show greater moisture in the
column compared to today, with similarly weak flow aloft. Lapse
rates are steep in the low-levels but modest to weak aloft. CAPE
profiles are tall with ELs over 12km and values around 2000-3000
J/Kg. Despite weak flow, frontal forcing combined with the
buoyant atmosphere should allow for convection by the afternoon.
Severe weather is not expected, but an isolated downburst capable
of strong/marginally severe wind gusts cannot be ruled out.

Temperatures...heat advisory continues into Friday with yet another
hot and humid day expected. Lows in the mid 70s should provide
little nocturnal relief and exacerbate heat-related health
effects.

&&

.LONG TERM (Friday night through Thursday)...
Issued at 254 PM EDT Thu Jun 26 2025

A Rex Block over the SE CONUS has kept a strong ridge over the Ohio
Valley, resulting in an extended heat wave for central Indiana. The
Rex Block creating the extended heat wave over the Ohio Valley will
begin to break down tomorrow through the weekend, mostly related to
the arrival of a weak and slow moving low level shortwave over the
Great Lakes region. As the shortwave nears late Friday into Saturday
an increase in lift will likely allow for continued scattered to
numerous coverage of showers and thunderstorms Friday night into
Saturday.  Given the presence of the shortwave, there is likely to
be some near surface high pressure building in from the NW on
Saturday, with a push of slightly drier air along with its arrival.
This will slowly decrease precipitation chances throughout the day
Saturday from NW to SE. By Sunday, this dry air mass should
encompass all of central Indiana, significantly reducing PoPs. With
greater cloud coverage, and the arrival of a slightly drier air mass
on Saturday, it is likely that temperatures will be more limited,
with highs slightly lower; in the upper 80s.

Even with the shortwave present, upper level forcing will be very
weak, with marginal shear through the lowest 6km. This should limit
storm organization, with any severe weather expected to be very
isolated.

The ridge will continue to break down early next weak, with more
seasonal temperatures expected Monday through Wednesday (mid 80s).
Low to mid level moisture is expected to stick around for early next
week as well, leading to daily thunderstorm chances once convective
temperatures are reached. Generally, synoptic dynamics are expected
to remain weak, leading to the continued expectation of unorganized
thunderstorms, but model uncertainty is high on any low level
features for a more mesoscale specific threat.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 115 AM EDT Fri Jun 27 2025

Impacts:

- Wind gusts in the low 20KT range Friday afternoon

- Isolated to scattered thunderstorms near peak heating to early
  evening Friday

Discussion:

Another hot and humid period expected across the TAF sites today,
with primarily VFR conditions outside of any convection.

Winds will gust from midday through early evening, generally in the
20-23KT range from about 220-240 degrees. These gusts will subside
in typical diurnal fashion after sunset.

Another day of thunderstorm activity is expected this afternoon into
early evening, with perhaps a bit more coverage as a weak boundary
approaches the region. Will carry PROB30 groups at all sites near
peak heating into the evening.

&&

.IND WATCHES/WARNINGS/ADVISORIES...

Heat Advisory until 8 PM EDT this evening for INZ021-028>031-
035>049-051>057-060>065-067>072.

&&

$$

UPDATE...50
SHORT TERM...Eckhoff
LONG TERM...Updike
AVIATION...Nield