Plainfield, Indiana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

834
FXUS63 KIND 201045
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
645 AM EDT Sun Jul 20 2025

.KEY MESSAGES...

- Flash Flood Watch in effect 1 PM today through 8 PM Monday

- Multiple rounds of showers and storms are expected today into
  Monday, with locally heavy rainfall and flash flooding possible

- Strong to severe storms will be possible today into tonight, with
  damaging winds the primary threat, although large hail or an
  isolated tornado cannot be ruled out

- Hot and very humid next Wednesday-Friday, yielding widespread and
  potentially dangerous maximum heat indices in the 100s.

&&

.SHORT TERM (Today and tonight)...
Issued at 346 AM EDT Sun Jul 20 2025

Primary concerns through the next 24-30 hours will be multiple
rounds of storms possible along a remnant surface boundary and
multiple outflow boundaries, as well as a threat for strong to
severe storms today into tonight.

While confidence is fairly high in the occurrence of multiple rounds
of precipitation in the short term, confidence in exact details is
modest at best given both the mesoscale dependencies which will
heavily influence each subsequent round of convection, and the
difficulties even high resolution convective allowing models have
with resolving details in such weakly-forced environments. As prior
discussions have mentioned, individual CAMs should be taken with a
grain of salt.

That said, an extremely moist airmass is in place across the area,
with column precipitable water values near or in excess of two
inches, which is near climatological maximum, and this airmass will
remain in place through tonight into Monday. In addition, wet bulb
zero heights frequently in excess of 13kft and deep saturation will
promote highly efficient warm rain processes. Portions (though not
all) of central Indiana have received significant rainfall in recent
days, and HREF local probability matched mean progs indicate
significant chances for rainfall amounts of 1-3+ inches over the
next 24-36 hours, and pockets of higher amounts are a significant
possibility given the aforementioned circumstances which will
promote very high rainfall rates in convection. With multiple rounds
of storms likely, and at least some potential for training depending
upon how boundaries become oriented or reoriented with time, and the
aforementioned high rain rate potential on fairly saturated ground
in some areas, flood potential is a significant concern.

Despite uncertainties with respect to the exact evolution of storms
and placement of highest rainfall amounts, in collaboration with
neighbors, will go ahead with a Flash Flood Watch for all of central
Indiana through Monday.

Today into tonight, bulk shear values will be a bit more robust than
in recent days, and diurnal heating will result in ample
destabilization ahead of the initial round of convection currently
over the mid Missouri and Mississippi valleys, which may promote
intensification or additional development with this activity as it
pushes into the area later today. Redevelopment of organized
convection may occur as the day wears on along the outflow boundary
left behind by round one, which will also potentially move into the
area later today into tonight. Damaging winds will be the primary
threat, though an isolated tornado or large hail report cannot be
ruled out given the relatively robust shear values.

A fairly wide range of high temperatures (low 80s to low 90s) is
expected today, with midday/afternoon storms in round one likely to
suppress heating across the north, while later activity in the south
will allow temperatures to rise to near or above 90. Lows tonight
will be near expected dewpoints in the upper 60s to mid 70s.

&&

.LONG TERM (Monday through Saturday)...
Issued at 346 AM EDT Sun Jul 20 2025

Monday and Tuesday...

Flash Flood Watch to continue into early evening Monday as the
lingering cool frontal boundary remains stretched from WNW-ENE along
and south of the I-74 corridor.  Corresponding dewpoint gradient to
range from perhaps upper 70s over southwestern counties to mid-60s
near/east of Muncie.  Considerable cloudiness and at times scattered
to possibly numerous showers may actually bring the lowest maximum
temperatures in nearly two weeks over the regions northeastern half
where low 80s are expected.  Overall light rainfall is expected, but
Flash Flood Watch is in effect through end of the day Monday given
potential for areas of moderate/heavy rainfall...which may impact
areas with ample antecedent/recent rains.

Tuesday should be the most pleasant day of the long term, albeit
still sporting seasonably very warm and humid conditions.  The brief
taste of milder air from the passing northern surface ridge should
be greatest around dawn Tuesday when readings should drop to the low
60s over the region`s northeastern corner...with forecast lows along
the I-74 corridor in the mid-60s.  Mainly dry conditions Tuesday
should include a few afternoon showers near and south/west of
Bloomington, with most locations rebounding to the mid/upper 80s as
moderate humidity is quickly replaced by mainly 70-75F dewpoints by
the evening hours.

Wednesday through Saturday...

Upper subtropical ridge to build northward around the Tuesday night
timeframe and encapsulate Indiana and many surrounding states
through the end of the week.  This will set the potential stage for
another heat wave for most/all of the local region into this
weekend...although more concerning than the marginally-hot
afternoons will be anomalously high dewpoints maintained in the mid
to upper 70s, starting Wednesday afternoon.  Heat index values to
diurnally vary from around the mid-70s to potentially the 100-110
degree range. These afternoon maxima heat indices would be equal to
or slightly greater than those experienced amid the late June heat
wave.

Somewhat lower confidence in temperatures reaching the low 90s / and
heat indices exceeding 100 for the Friday-Saturday timeframe per
increased daytime convective/corresponding cloud chances.  Rain
chances are expected to exhibit an increasing trend from near-zero
Wednesday...to most-likely isolated cells Thursday...to more
scattered late-day showers/ t-storms through the late week.  The
late-week should see the pattern shift slightly east, which will
allow a ribbon of anomalously high precipitable water to slide into
the CWA amid weak forcing from a subtle southern end of a H500 wave
crossing the Great Lakes.  A few torrential downpours would be the
primary concern from any storms, with perhaps localized flooding
possible for any areas that saw heavy rain on consecutive days.
Organized severe weather appears unlikely given overall lack of
shear...although a few stronger cells could be possible around the
Thursday night timeframe under the passing wave.  The normal max/min
at Indianapolis from July 23 to August 14 is 85/66.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 645 AM EDT Sun Jul 20 2025

Impacts:

- IFR ceilings/MVFR visibilities improving to VFR by late morning

- Showers and thunderstorms possible at times from midday onward

Discussion:

Plentiful low level moisture has allowed low stratus and patchy fog
to develop overnight. This will improve gradually back to VFR by
late morning once mixing increases with sunrise.

Showers and thunderstorms along and ahead of a front will move back
into the area late morning into the afternoon hours, though
uncertainty precludes more than a PROB30 at any one point at this
time. Multiple rounds of activity are possible, though more
uncertain with time given the dependence on the evolution of prior
activity. Will carry showers at all sites after 00Z tonight, though
thunderstorms will remain a significant possibility.

Winds throughout the period will be less than 10KT, and will likely
vary significantly at times as the boundary moves into the area and
the impacts of convection are realized.

&&

.IND WATCHES/WARNINGS/ADVISORIES...

Flood Watch from 1 PM EDT this afternoon through Monday evening
for INZ021-028>031-035>049-051>057-060>065-067>072.

&&

$$

SHORT TERM...Nield
LONG TERM...AGM
AVIATION...Nield