199
FXUS63 KIND 180452
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1252 AM EDT Mon May 18 2026

.KEY MESSAGES...

- Very warm through Tuesday with highs in the mid to upper 80s

- Scattered severe storms possible both Monday and Tuesday with
  damaging winds, large hail and localized flooding

- Storms will end Wednesday as the front shifts south, but unsettled
  weather may return late week into next weekend

&&

.FORECAST UPDATE...
Issued at 952 PM EDT Sun May 17 2026

The forecast remains in good shape with only minor adjustments
needed to match observations. Expect quiet weather conditions
through the overnight period with surface and upper ridging across
central Indiana. Mostly clear skies will allow for diurnal
cooling though southerly flow should still keep lows in the 60s.

&&

.DISCUSSION (This evening through Sunday)...
Issued at 226 PM EDT Sun May 17 2026

Surface Analysis early this afternoon shows low pressure over
western KS. A warm front extended NE across IA to southern MI ahead
of this low. Strong high pressure was found near the Carolinas. This
was resulting in warmer southerly flow across Central Indiana, and
temperatures were rising toward the lower 80s. Dewpoints were high
also with this air mass, in the the 60s. Central Indiana was solidly
in the warm sector.

Aloft water vapor shows a moderately amplified pattern over the CONUS
with a deep trough over the Rockies and moderate ridging in place
from the southeastern states through the Great Lakes to western
Ontario. This was resulting in mainly a SW flow of warmer air across
Indiana, arriving from the desert southwest. A short wave within
this flow was found over WI, pushing NE and spreading shower over
WI.

Convective temperatures have been reached as GOES19 shows widespread
CU development across Central Indiana and radar remains quiet.

Tonight...

Quiet weather is expected tonight as Indiana will remain under the
influence of the strong high pressure to the southeast, and remain
in the warm sector. Forecast soundings overnight show a dry column,
and afternoon CU will be lost as daytime heating diminishes. Look
for decreasing clouds this evening followed by mostly clear skies.
High dewpoints are also in place. as dewpoints remain in the mid
60s, and a moderate pressure gradient remains in place overnight,
overnight low temperatures will only fall to the mid and upper 60s.

Monday and Monday Night...

An even warmer day is expected on Monday along with high chances for
showers and thunderstorms. Models how a short wave pushing through
the upper flow along with some tropical southerly flow aloft. This
in combination with daytime heating and warm and humid airmass
suggests a good situation for afternoon convection. HRRR shows an
area of thunderstorms poised to push across Central Indiana through
the afternoon showing a significant cold pool temperature drop in
its wake by later afternoon and early evening. Forecast soundings
show attainable convective temperatures with CAPE values over 1600
J/KG. Given these elements, will aim for a dry morning but will
include high chances for afternoon showers and storms. Some storms
could be severe with straight line wind damage. Look for high
temperatures in the middle 80s.

Showers and storms will exit the area on Monday night with only the
far SE parts of Central possibly having lingering showers from 00Z-
01Z. Forecast soundings over night show dry air within the lower
levels associated with a cold pool along with a return to southerly
winds as the synoptic southerly, warm sector flow takes over. Lows
on Monday night should be similar to the previous night, in the
middle to upper 60s.

Tuesday...

More chances for severe weather will be in play on Tuesday afternoon
and Tuesday night. Indiana will still be within the warm sector, as
a wave within the SW flow aloft pushes from the plains toward the
Ohio Valley. Again Forecast soundings show a favorable column for
storms with CAPE over 1700 J/KG  and moderate wind shear in place. A
stronger cold front will also pushing also pushing across Indiana on
Tuesday afternoon into Tuesday night, providing forcing. Ahead of
the front, providing forcing will also be a moderate LLJ of 40-50
knts. Thus confidence is high for another round of showers and
storms, again some of which could be severe, with damaging straight
line winds as the main threat. The front is expected to reach near
the Ohio river near 00Z, thus Tuesday night pops will be considerably
lower, although clouds and very light stratiform showers or
sprinkles will be possible in the wake of the front, particularly in
southern parts of Central Indiana.

Wednesday through Sunday...

Wednesday...

Clouds will be lingering across the area on Wednesday morning in the
wake of Tuesday night/s cold front. Forecast soundings show
plentiful lower level saturation, but subsidence arrives through the
day as high pressure builds to the northwest. This will overall lead
to the arrival of dry weather through the afternoon and into the
evening. Will keep any precip mentions contained to the morning
hours. With the arrival of a cooler air mass, Highs in the upper 60s
to around 70 are expected.

Thursday...Forecast soundings on Thursday remain dry as strong high
pressure moves through the Great Lakes, providing a cooler and dry
easterly surface flow across Central Indiana. Will continue a dry
forecast and partly cloudy skies.

Friday...Chances for rain will return again on Friday afternoon into
Friday Night. The previous surface high will have exited to the
east, allowing a return flow of a warmer and more humid airmass. As
the front passes, a weak wave will be pushing through the Great
Lakes, and the cold front will sag across Indiana. These ingredients
are enough to include some chances for showers and thunderstorms.

Saturday and Sunday...Models show mainly zonal flow in place aloft
on Saturday and Sunday. Higher confidence for dry weather is present
on Saturday as Friday`s front departs and high pressure over the
upper midwest begins to influence Indiana. This high looks to
maintain control over Indiana on Saturday into Sunday. However,
winds become more southerly on Sunday allowing a bit more moisture
to arrive. Early Forecast soundings show an inverted V sounding with
afternoon CAPE over 1500 J/KG. Given this, afternoon diurnal
convection cannot be ruled out and pops will need to be included.
Temperatures on Saturday will be in the 70s, with warmer highs
around 80 on Sunday.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 1252 AM EDT Mon May 18 2026

Impacts:

- LLWS lasting through daybreak at KHUF and KLAF

- Peak wind gusts at 25 to 30kts today

- A line of severe thunderstorms expected during the afternoon with
  showers continuing into the evening

Discussion:

Subsidence over the region early this morning leading to mainly
clear skies. Surface winds had diminished to 10kts or less courtesy
of the nocturnal inversion but strong winds above the inversion
within the boundary layer will maintain marginal LLWS focused
primarily at KHUF and KLAF through daybreak.

A large area of convection extending from the upper Mississippi
Valley southwest into the central Plains will track east through the
morning likely weakening before restrengthening this afternoon as it
interacts with a warm and humid airmass over central Indiana. Expect
an intense line of storms likely carrying a threat for damaging
winds to move across the terminals during the 17 to 21Z timeframe.
Restrictions to IFR and lower will accompany the line. Scattered
convection should linger into the evening before gradually
diminishing in coverage.

Windy conditions will develop quickly after daybreak with peak gusts
at 25 to 30kts prior to storms arriving in the afternoon.

&&

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

&&

$$

UPDATE...Melo
AVIATION...Ryan
DISCUSSION...Puma