841
FXUS63 KIND 180207
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1007 PM EDT Wed Jun 17 2026

.KEY MESSAGES...

- Another round of storms expected this evening into the early
  overnight

- Damaging winds and tornadoes are the main threats with large hail
  also possible

- Flood Watch through 2AM with rain amounts locally as high as 4
  inches

- Below normal temperatures will continue for much of the period

&&

.FORECAST UPDATE...
Issued at 1006 PM EDT Wed Jun 17 2026

In terms of the forecast, only a few changes were needed. First was
temperatures so that they match observations better as the north has
cooled off while across the south is still on the warmer side. Next
was to update the PoPs and clear out our NW from much of the showers
and storms as they have pushed south.

As of 10pm, severe weather is ongoing with numerous strong storms
and even a tornado warning in effect. Storms will continue to drift
ESE as the night goes on and should weaken or move out by around or
shortly after 2am. Continue to monitor warnings.

&&

.MESOSCALE UPDATE...
Issued at 730 PM EDT Wed Jun 17 2026

Surface mesoanalysis shows strongest pressure falls are located
across central Indiana with between 3-4 mb/2 hr. This is collocated
with the core of the 50-60 kt 850 mb jet per objective analysis and
recent IND VWP data. Thanks to locally backed low level flow and
moderately strong 700 mb flow, strong low level shear currently
exists across the region. An incredible 0-1 KM SRH from 700-800
M2/S2 and 0-3 KM SRH around 1200 M2/S2 has been noted recently on
VWP data.

So far the main limiting factors for a more significant tornado
threat across IL/IN with ongoing convection is substantial mid level
warming (700 mb temps around 10 C per STL ACARS sounding) combined
with modest surface based convective inhibition leading to weak 0-3
KM lapse rates under 6 C/KM, modest instability /1000-1500 MUCAPE/
and 50-100 J/KG OF MU/SBCINH/. The existence of this mid level
warming with forced ascent through the inhibition layer centered
from 850-700 mb combined with the strong 0-3 km shear has been
confirmed from recent storm chaser video feeds showing a classic
large base with laminar shape and limited low level vertical
motion/vorticity generation.

Continued low level moistening with dewpts rising into the lower 70s
per downstream obs in southern MO/IL combined with slight mid level
cooling (likely reason for renewed CI over wcentral IL) should
support a increasing surface based storm threat in the next 1-3 hrs.
Therefore there still remains a significant tornado threat, as low
level shear will remain near current values through 11 PM EDT before
gradually weakening from the west. The significant tornado threat
will include all of central Indiana, with the likelihood for
scattered very large hail and damaging winds gusts.

&&

.DISCUSSION (This evening through Wednesday)...
Issued at 148 PM EDT Wed Jun 17 2026

Overview.

A widespread and significant severe weather outbreak is expected for
today with the first round of mostly sub-severe storms moving
through Indiana and western Illinois at this time. Expectations are
for a second round of severe storms towards the evening and early
overnight hours with the threat for damaging winds, tornadoes, large
hail, and flash flooding. The threat for higher-end tornadoes will
be dependent on how long storms remain discrete, which currently
looks likely through at least Illinois and portions of western
Indiana. Flash flooding will also become a concern, especially
towards southern Indiana as the convective line slows.

Following tonight, the pattern will transition toward a quieter and
more stable state. While lingering moisture may cause some
cloudiness early Thursday, the overall trend through the remainder
of the week and into early next week is quiet with high pressure and
seasonal temperatures.

Rest of Today.

The synoptic pattern remains highly anomalous for mid-June,
characterized by a deep mid-level trough and a robust 130+ kt jet
streak translating into the southern Great Lakes. Surface analysis
reveals a deepening low to our northwest with an advancing cold
front that will serve as the primary focus for convective initiation
this evening. High-resolution guidance, including the 12Z and latest
HRRR runs, confirms a significant severe weather threat, with a
heightened concern for discrete supercellular development across
west-central Indiana with the 2nd round of storms. The environment
is undergoing a rapid, efficient moisture surge, with dew points
already rising into the low 60s towards southwestern Indiana. This
influx of high-theta-e air is expected to compensate for any
lingering morning cloud cover or convective inhibition, providing
sufficient buoyancy for surface-based convection.

Of primary meteorological concern is the highly anomalous kinematic
environment. Model soundings continue to depict elongated, highly
curved low-level hodographs with backed surface winds and nearly 70
kt flow at 1 km, creating an environment favorable for significant,
long-lived tornadoes if the cells can remain discrete. Current CAM
consensus suggests that west-central Indiana remains the primary
corridor for potential tornadogenesis, as storms here will be best
positioned to interact with maximized low-level helicity and
localized outflow boundaries before upscale growth into a more
linear mode occurs. While the potential for discrete, supercellular
cells is the immediate priority, the transition to a bowing line
segment later this evening brings an increasing risk of destructive
straight-line winds, potentially enhanced by wake low development.
Flash flooding also remains a secondary but serious hazard, as high
PWAT values and potential training of convective elements may lead
to rapid, localized rainfall accumulations. The situation remains
highly dynamic and warrants close monitoring of convective
initiation timing and the exact positioning of the surface warm
front as the afternoon progresses.

Outside of the severe weather, both flooding and strong gradient
winds will be a concern with the gradient wind threat mainly through
00Z and the flooding threat mainly associated with the second round
of convection. HREF PMMs show pockets of 4+ inches with some
uncertainty as to where the axis of heaviest rain will fall.
Confidence is currently highest across southern Indiana but with the
uncertainty, we plan on issuing a flood watch through the entire
forecast area, especially considering the very heavy rains so far
this June.

Thursday through Saturday.

As the potent cold front responsible for the Wednesday storms pushes
well to our east, a deep, dry northwesterly flow will become
established across the Ohio Valley. On Thursday, any lingering cloud
cover from the overnight period will quickly scatter and dissipate,
giving way to abundant sunshine. Model guidance shows a noticeable
drop in dew points throughout the day, leading to a very comfortable
afternoon with high temperatures in the lower to middle 70s.

Friday and Saturday will feature pleasant early-summer weather with
a surface high-pressure system tracking across the Great Lakes and
into the Ohio Valley. This system will suppress any potential for
convective development, ensuring clear to mostly sunny skies and
light, variable winds. With the lack of any significant forcing
mechanisms and a very dry air column, the forecast remains dry with
high confidence. Daytime temperatures will be pleasant, ranging from
the mid-70s on Friday to near 80 degrees by Saturday, while
overnight lows will settle into the cool and refreshing 50s.

Sunday through Wednesday.

The quiet conditions are expected to persist through the second half
of the weekend and into the early part of next week. Ensemble
guidance remains in strong agreement that an upper-level ridge of
high pressure will amplify across the central United States,
effectively keeping the pattern dry and stable pattern for Indiana.
Sunday will be another beautiful day, with temperatures nudging
slightly higher into the low 80s under mostly sunny skies.

Looking toward the beginning of the new work week, this ridge will
shift eastward, allowing for a gradual warming trend. By Monday and
Tuesday, afternoon highs are expected to reach the mid-80s. While
some long-range ensemble members suggest a potential breakdown of
the ridge by next Wednesday, the current moisture profile indicates
that any return to a more active, unsettled pattern will be delayed
until the latter half of the week.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 752 PM EDT Wed Jun 17 2026

Impacts:

- Showers and thunderstorms this evening and into the overnight. IFR
or worse conditions possible at times.

- Wind gusts over 25kt into the early morning hours.

Discussion:

Expect a line of convection moving from the northwest through 06Z.
IFR and worse conditions are possible especially in heavier rain,
along with severe convection.

Outside of convection winds gusts will be up to 25-35kt likely.
Higher gusts possible in stronger storms.

The rest of the period will generally be dry with some breezy
conditions, gusts up to 15-20 kts, possible into tomorrow.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 4 AM EDT Thursday for INZ021-028>031-035>049-
051>057-060>065-067>072.

&&

$$

UPDATE...KF
AVIATION...KF
DISCUSSION...White