271
FXUS63 KIND 161956
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
356 PM EDT Sat May 16 2026

.KEY MESSAGES...

- Thunderstorms, some possibly severe across far southern portions
  of central Indiana late this afternoon/early evening.

- Storm chances return Monday along with much warmer than normal
  temperatures Sunday through Tuesday with highs in the 80s.

- A frontal passage Tuesday into early Wednesday will bring
additional chances of severe storms along with cooler and drier
weather for the later part of next week.

&&

.MESOSCALE UPDATE...
Issued at 309 PM EDT Sat May 16 2026

Currently there is a weakening band of elevated convection that is
traversing W-Central portions of Indiana as it encounters a more
stable air over E-Central section of the state (MUCINH 100-200
J/KG). Temperatures have been stabilized greatly across the I-70
corridor, with readings still sub 70 F. Meanwhile, north and south
of this region, highs have warmed into the upper 70s to near 80
F. Combined with dewpts in the 65-68F range, surface based
instability has risen to 2000 J/KG in northern portions to between
2500-3000 J/KG in southern portions of central IN.

Another in a series of MCVs over W Central IL will continue to
progress eastward. Surface analysis shows that an earlier outflow
boundary over far southern IN has begin to shift northward extending
from a meso-low near St. Louis eastward into far southern sections
of central IN. TS activity over central IL will continue to
intensify in the region of this meso-low and outflow boundary while
gradually shifting into SW portions of central IN through 2200Z.
Damaging winds and isolated large hail will be possible, however
effective shear values remain marginal from 30-35 kts. In addition
to an expected increasing severe weather threat an additional threat
for heavy rain/flooding may develop, especially in areas that saw
heavier rainfall earlier today.

&&

.DISCUSSION (This evening through Saturday)...
Issued at 355 PM EDT Sat May 16 2026

Rest of this afternoon....

See the most recent mesoscale update forecast the forecast through
00Z. Precip probs have been risen to likely across southern portions
of the forecast area as a cluster of TS is expected to move eastward
from south-central IL.

Tonight....

Convection tied to the MCV will continue to move eastward before
gradually diminish late evening. Threat for isolated severe
winds/hail will be possible through 02Z /10 PM EDT/. Overnight, a
slowly NE moving warm front combined with a 30-40 kt low level jet
will likely support renewed elevated convective development after
05Z. PoPs have been raised a category to account for this increasing
potential.

Sunday/Sunday Night...

Scattered TS will come to an end early Sunday (before 15Z) as the
warm front lifts northward. Gusty S-SW winds will develop by late
morning lasting into the afternoon owing to an increasing surface
pressure gradient and modest low level flow in the boundary layer.
High temps are expected to easily rise in the 80s area wide by
afternoon with 850 temps around 17-18C. Combined with dewpoints in
the lwo-mid 60s, heat indices are expected to be in the mid-upper
80s, close to the warmest apparent temps since late March. Skies are
expected to be mostly clear Sunday and Sunday night with just
afternoon cumulus and increasing cirrus overnight from Plains
thunderstorm activity.

Monday/Monday Night...

Model consensus is that a relatively innocuous mid level vort
max/lead shortwave trough associated with the southern jetstream
/per sat off of Baja CA coast/ will move NE across Mexico and TX and
into the Ozarks/Mid MS valley by Monday afternoon. With weak
inhibition and moderate instability /MLCAPE around 2000 J/KG/
noted on forecast soundings, scattered TS are expected for form just
west of central IN during the mid-late afternoon. Weak 0-6 km shear
will limit threat for more significant severe threat, but moderate
anvil venting and low level flow may support a low end hail/damaging
wind threat if activity can become organized linearly. This activity
is expected to weaken overnight Monday night with loss of heating
amidst weak forcing. High temps on Monday are once again expected to
be well above normal, despite some increase in clouds cover with 80s
areawide.

Tuesday/Tuesday Night...

A cold front will push southward across the plains and upper
Midwest, however timing of the front is somewhat uncertain 3 days
out. Thunderstorm activity is expected to be numerous along the
front with deep layer forcing and moderate instability
/CAPE 2000-3000 J/KG/. Convective mode is expected to be fairly
linear convective with damaging winds the primary threat, per the
SPC Day 4 slight risk outlook. In addition, locally heavy rainfall
may lead to minor flooding.

Wednesday into Saturday....

The primary cold front is expected to push across central Indiana
early on Wednesday. In the wake of the front, cooler and drier air
is expected through Thursday. Thereafter, there is some disagreement
with the strength of the shortwave trough moving into the Rockies
and Plains and the consequent timing and coverage of additional
precip development moving back into central Indiana going into the
Memorial Day weekend/500 festivities. High temps are expected to be
below normal Wed and Thursday rising to near normal by Saturday.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 143 PM EDT Sat May 16 2026

Impacts:

- SHRA and -TSRA this afternoon, highest confidence through 22Z.

- Sporadic 18-22kt wind gusts at times today and again Sunday
  afternoon

- Low end MVFR ceilings with possible TSRA early Sunday morning.

Discussion:

Broken line of TS will continue to move E-SE across portions of
central Indiana through the afternoon...before an expected weakening
and ending during the evening. TS have been removed from KLAF as the
main boundary focus has shifted south. Elsewhere have a TEMPO or
PROB30 of -TSRA in the forecast through the 20-22Z period. Outside
of TS, gusty SW winds around 20 kts will continue until early
evening.

Overnight, a warm front will slowly lift northward. Moist ground and
some clearing skies will lead to a reduction in VIS to MVFR as well
as lowering ceilings into MVFR. Some guidance suggest possible
patchy fog, but confidence not high enough to lower into IFR
category. Associated with the warm frontal passage, there will be a
chance of scattered TS. Have introduced a PROB30 for early Sunday
morning earliest south, (7-12Z) to account for this potential.

As the warm front lifts northward, skies will clear with gust winds
out of the S-SW (180-190 deg) by late morning through the remainder
of the forecast.


&&

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

$$

MESOSCALE...Crosbie
AVIATION...Crosbie
DISCUSSION...Crosbie