771
FXUS63 KIND 281631
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1231 PM 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

&&

.FORECAST UPDATE...
Issued at 930 AM EDT Sat Jun 28 2025

Remnant frontal boundary weakening and becoming increasingly diffuse
as it is draped across the forecast area this morning. Axis of mid
and high level clouds coinciding with what is left of the boundary
bisecting central Indiana with mainly sunny skies north and south.
Most of the showers and storms from earlier this morning had
diminished as well. 13Z temperatures were in the 70s.

Scattered convection will redevelop within the unstable environment
this afternoon but the focus will shift to the southern half of the
forecast area as the boundary remnants drift south. Torrential
rainfall and the potential for localized flooding remains a primary
concern with storms later today especially with stagnant wind flow
and little to no shear supportive of much slower storm movement than
Friday. Stronger cells will again carry a gusty wind threat as
downdrafts collapse but overall coverage is likely to be lower this
afternoon than the last few days.

While slightly drier air will advect into the region from the north
as the afternoon progresses surface dewpoints will be slower to
drop...taking until late day or more likely this evening before
falling back into the mid 60s over northern counties. Not out of the
possibility that isolated cells could persist as far north as the I-
70 corridor into the early evening before diminishing as a result.
Have not made any changes to extend lower pops a bit longer into the
evening but this will be a trend to monitor going into the afternoon.

Highs in the mid and upper 80s look reasonable as cloud coverage
should drop off into the afternoon. Zone and grid updates out.

&&

.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 (18Z TAF Issuance)...
Issued at 1231 PM EDT Sat Jun 28 2025

Impacts:

- Isolated to scattered thunderstorms this afternoon and evening,
  focused largely south of I-70

- Patchy fog tonight, perhaps dense in spots

Discussion:

Much of the high level clouds have diminished early this
afternoon...replaced by a developing diurnal cu field. The cu will
drift south through late day as drier air advects south. Isolated to
scattered convection will again develop over the next few hours
focused largely across the southern half of central Indiana. KBMG is
the terminals with the greatest chance to be impacted but there are
hints at isolated activity as far north as the I-70 corridor through
early evening which could impact KHUF or KIND as well. For
now...coverage is not expected to be great enough to warrant a
mention in the forecast but will monitor and update as needed. Much
of the convection will be diurnally driven and will dissipate near
sunset.

Light to calm winds and eventually clearing skies overnight late
tonight may promote fog development...and locally dense fog is not
out of the question. Will carry MVFR fog with a BCFG mention near
daybreak Sunday at the outlying sites. Fog will diminish quickly
Sunday morning with establishment of diurnal cu again by midday as
deeper moisture lifts back north across the area. Isolated to
scattered convection will be possible again Sunday afternoon with
the potential at greater coverage than anticipated this afternoon.

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

&&

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

&&

$$

UPDATE...Ryan
SHORT TERM...Nield
LONG TERM...Melo
AVIATION...Ryan