Flash Flood Warning 23, NWS Indianapolis, IN

Area Forecast Discussion
National Weather Service Indianapolis IN
1249 AM EDT Tue Jul 1 2025

.KEY MESSAGES...

- Rain shower/storm chances persist through tonight with the
  potential for localized flash flooding

- Isolated strong wind gusts are also possible this afternoon and
  evening

- Drier and slightly cooler weather expected this week before warmer
  and more humid conditions return Friday into next weekend

- Scattered showers and thunderstorms possible over the weekend

&&

.FORECAST UPDATE...
Issued at 958 PM EDT Mon Jun 30 2025

Isolated convection continues across central Indiana this evening.
Much of the convection is east and west of the area, associated with
areas of forcing.

A southern stream shortwave is across southern Illinois, and the
right entrance region of an upper jet was across northern Illinois.
An outflow boundary from earlier convection was moving south across
central Illinois and the northern portion of the forecast area.

Meanwhile, satellite blended precipitable water products show an
increase in mid level moisture near the southern stream wave to go
along with the already moist lower levels.

The forcing from the aforementioned mechanisms will work with the
moisture to produce numerous convection across the southern forecast
area tonight. Have upped PoPs into the likely category there
tonight. Will have lower PoPs north where forcing is weaker.

Instability will weaken diurnally, so odds of severe storms are
pretty low. Cannot rule out gusty winds with a collapsing storm
though. The main hazard will be heavy rain and localized flooding,
especially south. Will have to especially watch areas that were
harder hit with rain last night.

Low temperatures look reasonable.

&&

.MESOSCALE UPDATE...
Issued at 1224 AM EDT Tue Jul 1 2025

**Flash Flooding likely across portions of South Central Indiana
during the overnight hours**

Satellite and radar imagery show a cluster of thunderstorms slowly
moving into portions of Southwest and South Central Indiana
Indiana...the same areas which received 3-8 inches of rainfall over
the past 24-36 hours. Flash flooding is likely with this activity
through the overnight hours. The environment across the region
this evening is conducive for continued convective development and
maintenance of the cluster as ACARs soundings indicate a very
moist, unstable environment with sufficient upper level support.
Flash Flood warnings have already been issued for Knox and
Sullivan Counties and more headlines may be needed further
downstream over the next several hours.

From WPC:

Deep convection has persisted across much of southern/southeastern
Illinois over the past couple hours despite nocturnal boundary layer
cooling.  Abundant low- and mid-level moisture across the area ahead
of the convection was helping to maintain an axis of 1000-1500 J/kg
MLCAPE ahead of the storms while also supporting efficient rain
rates within the convection. Areas of 1-3 inch/hr rain rates have
been estimated per MRMS, which has occasionally exceeded local FFG
thresholds and prompted spots of low to moderate MRMS Flash
responses.

Unfortunately, this cluster of heavy-rain-producing convection was
moving toward portions of southern/central Indiana (near
Bloomington) that have received between 3-8 inches of rainfall over
the past 24-36 hours.  Ground conditions are saturated as a result,
and it is likely that as the cluster of storms moves eastward, Flash
Flood Guidance thresholds will be exceeded and excessive runoff will
occur. Locally significant flash flood impacts cannot be ruled out.

&&

.SHORT TERM (This evening through Tuesday)...
Issued at 324 PM EDT Mon Jun 30 2025

Unsettled weather continues through tonight as moisture is still
in place. As of this afternoon, small isolated showers have been
popping up across central Indiana. The ongoing storms are staying
shallow and thus small and weak for now. Should an isolated storm
strengthen and be taller, can't rule out a stronger wind gust
being produced, but confidence is low in stronger storms forming
this afternoon.

Better forcing is expected to arrive later this evening as the cold
front moves through, but that will more likely come in the form of
more widespread showers than this afternoon and a few thunderstorms.
South-central Indiana saw multiple inches of rain last night, so if
those areas see even brief heavy rain again tonight, flooding could
again be a concern. Elsewhere across the forecast area should be
able to handle heavy rain but people should still be aware of the
chance of localized flooding.

Latest CAMs have slowed the eastward exit of the front and
associated showers into tomorrow morning, but much of Tuesday is
expected to be dry and relatively cooler with highs near normal for
this time of year.

&&

.LONG TERM (Tuesday night through Monday)...
Issued at 324 PM EDT Mon Jun 30 2025

Generally dry and quiet weather is expected through the remainder of
the week, with some precipitation chances over the weekend.
Northwesterly flow aloft gradually transitioning to broad ridging
will allow for a slow warm-up as well.

A weak cold front pushing through on Tuesday will allow a
continental polar air mass to flow southward. Back trajectories
point towards northwestern Canada as the source region for this air,
and so dew points will finally drop to reasonable levels (upper 50s
and 60s) for the first time in over a week. Despite the air
originating in NW Canada, wildfire smoke shouldn't be too much of a
concern this time around. Visible satellite does not show much in
the way of smoke upstream, since the atmosphere has been fairly
active up there which hasn't allowed smoke to build up sufficiently.
However, there is still some smoke...so a period of slightly hazy
skies cannot be ruled out at times.

By Thursday we'll be entering an upper-level pattern characterized
by broad ridging aloft. This should allow dew points to gradually
rise along with increasing ambient air temps. Precipitation looks
unlikely, though some members of guidance are showing isolated
showers/storms Thursday along a weak warm front developing as
ridging builds.

July 4th: Guidance is in good agreement showing high pressure at the
surface. Combined with our location downstream of the primary ridge
axis, a subsident atmosphere is likely and so precipitation is not
expected. Temperatures may reach 90 degrees by Friday with dew
points once again reaching 70.

Large-scale ridging looks to break down over the weekend with
guidance showing a weak trough and cold front approaching from the
northwest. With increasing dew points and instability, some showers
and thunderstorms are possible both Saturday and Sunday. Flow aloft
is very weak on Saturday, so any activity should be pulse-like / pop-
up in nature, and coverage is likely to remain low. However, as the
cold front presses southward on Sunday, forcing should increase
enough to increase the coverage and likelihood of precipitation.

Guidance still differs regarding the timing of the front, which may
have implications on which day has the best chance of rain. A faster
front would shift things more into Saturday, and a slower front
would lead to Sunday or perhaps into Monday seeing better rain
chances. We will keep broad but low precip chances Saturday, Sunday,
and Monday for now until model consensus improves.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 1249 AM EDT Tue Jul 1 2025

Impacts:

- MVFR to briefly IFR vsbys at HUF/IND/BMG through 12Z, worst at BMG

- TSRA at times at BMG through 12Z

- Winds shifting through period from WSW to NW

Discussion:

Frequent showers to continue at HUF and BMG through daybreak with
potential for additional development near IND. Greatest impacts will
be at BMG where frequent MVFR and occasional IFR vsbys are expected
along with the best chance for MVFR cigs. Rain will come to an end
after daybreak with clearing skies. Winds will continue to become
more northwesterly with a low chance for gusts to 18kts this
afternoon.

&&

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

UPDATE...50
SHORT TERM...KF
LONG TERM...Eckhoff
AVIATION...White

Hazardous Weather Outlook
National Weather Service Indianapolis IN
429 PM EDT Mon Jun 30 2025

INZ021-028>031-035>049-051>057-060>065-067>072-012030-
Carroll-Warren-Tippecanoe-Clinton-Howard-Fountain-Montgomery-Boone-
Tipton-Hamilton-Madison-Delaware-Randolph-Vermillion-Parke-Putnam-
Hendricks-Marion-Hancock-Henry-Vigo-Clay-Owen-Morgan-Johnson-Shelby-
Rush-Sullivan-Greene-Monroe-Brown-Bartholomew-Decatur-Knox-Daviess-
Martin-Lawrence-Jackson-Jennings-
429 PM EDT Mon Jun 30 2025

This hazardous weather outlook is for central Indiana.

.DAY ONE...Tonight.

Scattered thunderstorms are expected through tonight. Locally heavy
rain producing flooding along with lightning will be the primary
hazards. Isolated strong to marginally severe storms with strong to
damaging winds are possible mainly this evening.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Isolated to scattered thunderstorms focused during the afternoon and
evening will return this weekend.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report any strong wind gusts or localized
flooding observed through Monday, though large scale spotter
activation is not anticipated.

&&

More information, along with other weather, hydrological and climate
information can be found at http://weather.gov/ind