966
FXUS63 KIND 281057
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
657 AM EDT Sat Jun 28 2025

.KEY MESSAGES...

- Slightly less hot today, though still quite humid

- Scattered daily afternoon showers/t-storms through at least Monday,
  isolated strong wind gusts are possible as well as localized flooding

- Drier and slightly cooler conditions expected for the middle of next week

&&

.SHORT TERM (Today and tonight)...
Issued at 307 AM EDT Sat Jun 28 2025

The presence of a weak and diffuse surface boundary, not to mention
myriad remnant outflow boundaries from recent rounds of convection,
in the background setting of a continued warm and very moist
airmass, will set the stage today for additional thunderstorms,
primarily over the southern third to half of the area near and after
peak heating.

Very weak flow throughout the depth of the troposphere will result
in slow storm motions, and minimal to no severe threat beyond the
outside shot at a localized downburst owing to the minimal shear.
Thus, the primary hazards will be the typical lightning concerns, as
well as locally heavy rainfall and isolated flash flood concerns,
given the slow storms and precipitable water values approaching 2
inches, near the top end of climatology for what is already nearing
the peak PWAT time of year as it is.

Despite the ample instability, coverage should be limited to
isolated to scattered at best with a lack of large scale forcing for
ascent or other significant forcing mechanisms beyond the
aforementioned weak boundaries.

Temperatures will still be warm, and conditions quite humid, but not
quite as oppressive as much of this week. Expect most areas to top
out mid to upper 80s, perhaps a few areas near 90, which, combined
with dewpoints largely in the upper 60s to low 70s will produce peak
heat index values in the mid 90s, about 5-10 degrees cooler than
much of the week. Lows tonight will drop back to near dewpoints in
the upper 60s to low 70s, and depending upon degree of clearing, may
set the stage for some patchy dense fog, though this will depend
heavily on amount of debris cloudiness from convective activity
later today. Winds will likely be light enough to support at least
some light fog.

&&

.LONG TERM (Sunday through Friday)...
Issued at 307 AM EDT Sat Jun 28 2025

Sunday through Monday night..

Expect elevated rain chances early in the period as a shortwave
trough and associated cold front approach. Gradually strengthening
southerly flow ahead of the system will help push deeper moisture
northward on Sunday. This combined with daytime heating should
promote scattered diurnal convection. NBM POPs appear too high
during the day given weak overall forcing so decided to lower rain
chances. Still expect rain chances around 20-40% over the north half
of central Indiana and 40-50% across the south. POPs may need to be
lowered even more in future updates depending on model trends.

Stronger dynamics from the upper wave moving in will then likely
lead to more widespread convection late Sunday night into Monday.
Deep-layer shear is weak, but a few strong storms with gusty winds
cannot be completely ruled out Monday as moderate destabilization
occurs. The system should then begin to shift east Monday night with
rain chances diminishing. Expect highs to generally be in the upper
80s to near 90F over the weekend and mid-upper 80s on Monday.

Tuesday onward...

Mostly quiet weather conditions are expected Tuesday through
Thursday as weak high pressure settles in. In addition to a drier
forecast, slightly cooler temperatures in the mid 80s are expected
Tuesday and Wednesday. Dewpoints falling into the 60s should also
feel more comfortable compared to the very humid conditions over the
past week. Ensemble guidance suggest moisture begins to stream back
into the region ahead of another system towards the end of the week.
This will lead to increasing rain chances, but increasing model
spread leads to higher uncertainty in exact timing and details.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 656 AM EDT Sat Jun 28 2025

Impacts:

- Isolated to scattered thunderstorms again Saturday, primarily south

- Patchy fog tonight, perhaps dense in spots

Discussion:

Expect scattered to broken VFR cumulus, with convection potentially
developing over the southern third to half of the area today. Will
carry a PROB30 thunder group at BMG, but IND/HUF may not be entirely
out of the woods. Much of the convection will be diurnally driven,
dissipating near sunset.

Light to calm winds and eventually clearing skies overnight late
tonight may promote fog development, and dense fog is not out of the
question. Will carry MVFR fog with a BCFG mention near daybreak
Sunday at the outlying sites.

Winds will generally be less than 10KT through the period.

&&

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

&&

$$

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