401
FXUS63 KIND 050521
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
121 AM EDT Thu Jun 5 2025

.KEY MESSAGES...

- Storms to continue through the rest of the overnight

- Additional marginal risk for severe weather possible tomorrow
  and Friday as well.

- Localized heavy rain and flooding a concern at times tonight
  through Friday

- Unsettled and stormy weather continues through the end of the week
  with additional storm chances early next week

- Seasonable temperatures late week into early next week

&&

.FORECAST UPDATE...
Issued at 924 PM EDT Wed Jun 4 2025

Forecast is in good shape. A stationary frontal boundary draped
across northern Indiana will continue to remain nearly in place over
the next 12 hours. However, a convectively generated outflow
boundary will act as the effective front and focus for low level
convergence. At the time of this writing, this boundary was located
from W-Central IN /near Terre Haute/ up to near Muncie.

The earlier capping inversion centered near 10 kft noted on ACARS
/aircraft soundings/ near IND airport has begun to erode in the
last few hours indicative of mid level moistening/cooling ahead of
a convectively generated vort max over the MS valley.
Thunderstorm activity over far western portions of central Indiana
will continue to develop eastward through the rest of the evening
and into the overnight time frame into a modestly convective
unstable airmass (MLCAPE 1000-1500 j/kg). The greatest coverage of
thunderstorms across the forecast area will be between 11 pm and
4 am before the mid level forcing departs to the east, although
isolated TS will remain possible through 12Z in eastern/southern
portions of the forecast area.

Precipitable water values will continue to increase to as high as
1.80. Storm motions will generally be parallel to the low level
forcing /outflow boundary orientation/. This will support cell
training and the potential for heavy rainfall rates and localized
flooding. In addition, modest increase in the mid level wind shear
/0-6 km 30-35 kts/ may support marginal storm rotation and brief
threat for damaging wind gusts, especially if any storms can root
into the boundary layer south of the outflow boundary.

&&

.MESOSCALE UPDATE...
Issued at 120 AM EDT Thu Jun 5 2025

As of early this morning widespread convection continues to slowly
propagate eastwards with storms generally moving in a northeasterly
direction. The nocturnal inversion has limited the severe weather
threat, but lightning has gradually increased in the ongoing storms
as the LLJ ramps up and some elevated instability advects into the
area. The strongest storms are currently in the Knox county area
where a lightning uptick has corresponded to a localized gusty wind
threat with a recent report in Knox county of 45 mph.

ACARs soundings show the instability is generally in the 800mb to
700mb layer which lines up with the generally shallow nature of the
convection. Expectations going forward for the next few hours will
be a continued eastward progression with nearly stead state
lightning coverage and a decreasing threat for severe weather as the
nocturnal inversion continues to strengthen. The propagation has
been sufficient to limit the flooding threat but some localized
flooding is likely ongoing across portions of Clinton/Tipton/Howard
counties where two rounds of convection impacted.

&&

.SHORT TERM (This evening through Thursday)...
Issued at 305 PM EDT Wed Jun 4 2025

The approaching cold front has slowed significantly and has sat just
to the NW of central Indiana for much of the day, inching
northeastward. Showers have been passing through our far NW counties
this afternoon and thunderstorm coverage is expected to increase as
the day continues. A few storms may be severe with isolated
damaging winds possible through sunset as instability increases
during that time but there is also CIN that will help suppress
widespread strong storm concerns.

Through the night, storm and shower coverage will continue to
become more widespread across the forecast area. Model soundings
show the column becoming saturated overnight as well with models
showing PWATs of 1 to over 1.5 so localized heavy rain and
potential flooding could be a concern.

The front will continue to be draped across the region tomorrow,
continuing the chances for showers and storms. Afternoon warming
could again provide enough instability for a marginal risk of a few
severe storms with damaging winds across the SE portion of the
forecast area.

Highs today are in the low to mid 80s. Tonight will again be warmer
than normal with lows in the mid to upper 60s. Tomorrow`s highs will
be only slightly above normal as much of the front will have creeped
far enough east by peak heating.

&&

.LONG TERM (Thursday night through Wednesday)...
Issued at 305 PM EDT Wed Jun 4 2025

A messy and unsettled pattern continues into the extended period as
a frontal boundary meanders over the region and is blocked by a
strong surface ridge off the Mid Atlantic coast. Periodic showers
and thunderstorms will impact the Ohio Valley through at least late
Friday night before the front shifts south. Relatively weak deep
layer shear and poor lapse rates will limit but not completely
remove the severe risk in a moderately unstable environment Friday
afternoon and evening.

The most likely scenario will be a messy multicellular convective
mode pulsing in intensity with localized damaging winds and perhaps
large hail with the strongest cells as cores collapse. The greatest
potential for isolated strong to severe storms should be focused
across the southern half of central IN where stronger instability
and effective shear will reside. The main impacts from storms though
will be the potential for locally heavy rain and flooding as PWATs
climb to 1.75 to 2 inches and storms are likely slow movers with
weak wind flow aloft.

Latest guidance suggest some improvement to MVFR most areas
tomorrow afternoon. uncertainty in the potential for another round
of rain on Saturday as a shortwave approaches. Deeper gulf
moisture should be displaced south of central Indiana by early
Saturday before potentially shifting back north during the day.
However, models show significant discrepancies regarding the
intensity of the shortwave and overall moisture return ahead of
it. Low chances for precipitation will remain into Saturday using
a blended approach for these reasons. Expect rain chances to be
refined once models become better aligned.

Weak surface high pressure should provide mostly quiet weather
conditions late Saturday through the first half of Sunday with drier
air filtering in. This will likely be short lived though as a strong
low pressure system moving north of the Great Lakes late Sunday into
Monday pulls a cold front through the region. Once the front passes,
a large area of high pressure will build into the Ohio Valley with
dry and seasonable conditions for the middle part of next week.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 120 AM EDT Thu Jun 5 2025

Impacts:

-Scattered TSRA through 09Z, becoming isolated through 12Z
-Periodic SHRA through the day, additional TSRA chances after 18Z
-Generally VFR cigs through 15Z, MVFR to potentially IFR after
-IFR to LIFR cigs/vsbys late tonight due to fog

Discussion:

As of 05Z the strongest convection was impacting IND and BMG with
lighter showers with occasional thunder at LAF and HUF. The highest
coverage of storms will be through 09Z with convection becoming more
scattered through the rest of the morning hours. While there may be
a few rumbles of thunder through the day, coverage will be too low
to warrant a prevailing 12 hours of VCTS.Confidence in higher
thunder coverage begins to increase after 18Z as peak heating
arrives, but coverage should still be lower than the ongoing
thunderstorms.

Cigs will generally remain VFR with brief MVFR conditions through
12Z in the strongest storms. Confidence is increasing in MVFR cigs
through much of the daytime hours with a low threat for IFR cigs.
Much lower cigs arrive in the 24-30 hour timeframe with the
potential for fog after 09Z Thursday night. Vsbys will remain VFR
outside of the strongest storms before the aforementioned period of
fog.

Winds will generally remain light and variable through 15Z before
becoming predominately northerly at all sites but BMG where winds
will remain southerly. Winds will then drop to near calm during the
timeframe of potential fog.

&&

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

$$

MESOSCALE...White
UPDATE...Crosbie/JP
SHORT TERM... KF
LONG TERM... Ryan/Melo
AVIATION...White