Flash Flooding and Damaging Winds in Indiana, May 18 to 19, 2026

Area Forecast Discussion
National Weather Service Louisville KY
241 PM EDT Mon May 18 2026

.KEY MESSAGES...

* Today through Tuesday, temperatures are expected to warm into the
  mid 80s to low 90s. Some daily max temperature records could be
  challenged.

* This afternoon/evening, showers and/or thunderstorms arrive,
  especially for our northwestern counties. This is mainly a wind
  and hail threat.

* A line of strong to severe storms is expected to move through
  ahead of a cold front on Tuesday, possibly bringing strong winds
  and hail. The line will weaken as it moves east over the region.

* More active weather arrive later this week as multiple rounds of
  showers and scattered thunderstorms are possible going
  into Memorial Day weekend.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 241 PM EDT Mon May 18 2026

Current mesoanalysis shows 2000-2500 J/kg of uninhibited SBCAPE,
about 20kts of deep layer shear, and steep lapse rates. Not seeing
much agitated Cu over our CWA just yet, but just to the west, we
have seen some initiation. Shear will slightly increase as the MCS
approaches the CWA, which will help storms to become slightly more
organized. Over the next few hours do expect some scattered strong
to severe storms, with a wind and hail threat. The threat area will
be small, over southern Indiana and just along the Ohio River. Most
of the region will be spared of any storms. Additionally, PWATs near
1.8-2.0 inches and a slowly moving line of storms will allow for
heavy rainfall. This line is also moving aprallel to the LLJ, which
will allow for training. Due to this, there is also a risk for heavy
rainfall to lead to some minor flooding issues over our far
northwestern areas in southern Indiana.

As the sun sets, we will quickly lose instability. Showers and
storms are expected to quickly dissipate. With broken sky cover and
light southerly winds, not expecting a great radiational cooling
night. Low temperatures will likely remain warm in the upper 60s and
low 70s. This will be close to warm minimum records for May 18.

Ahead of an approaching cold front, WAA will continue to keep
temperatures in the upper 80s and brushing 90. This will help SBCAPE
to increase near 3000J/kg. Dew points will also creep into the upper
60s and low 70s. Though shear will remain low around 20kts. Pulse
summertime thunderstorms will be possible in the afternoon prior to
the cold front and association line of storms. When the cold front
approaches, we are expecting a decaying line of storms to outrun the
best forcing along the cold front. Wind and hail will be the main
threat on Tuesday over the northwestern 2/3rd of the CWA. The cold
front will begin to slow its progression southward Tuesday night,
making it through most of the CWA by Wednesday morning.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Issued at 241 PM EDT Mon May 18 2026

As the cold front slowly sags the the south on Wednesday, widespread
showers and scattered thunderstorms are expected, especially for the
southern half of our area. Rich moisture along the front will help
fuel these showers and storms, with LREF PW values ranging from 1.4-
1.7" (>95th percentile climatologically). Instability to the south
of the front will also help fuel these showers, with LREF mean
SBCAPE around 750-1000 J/kg. The wind shear profile is very meager,
so we don't currently expect severe weather at this stage. With the
front moving through, temperatures will much closer to normal for
this time of year, with highs in the mid-to-upper 70s north of the
front in southern Indiana and northern Kentucky, and highs in the
low 80s south of the front in south central Kentucky.

The front stalls out just south of our area by Thursday, but with
some moisture still in place over our far southern counties chances
for showers will be possible (35-50%). With northerly flow at the
surface, temperatures across the region will be slightly cooler than
Wednesday, with highs in the low-to-mid 70s.

Though an area of surface high pressure tries to build in over the
Great Lakes and Ohio Valley regions Thursday, a broad upper level
trough over the western CONUS pushes eastward and drives the high
out of the area. Ahead of the trough axis, a series of shortwaves
surges northeastward, lifting the frontal boundary northward Thursday
night. Considerable southerly flow at the surface and aloft will
allow deep moisture to surge back northward, helping set up a few
decent periods of showers and some thunderstorms into Memorial Day
weekend. The southerly flow will also allow temperatures to rise
back up into the 80s by the weekend, but with dew points again in
the mid 60s, it will also feel rather muggy outside. The more
active pattern for rounds of showers is currently expected to last
through the end of the forecast period, so a little bit of drought
relief may finally be on the way.

&&

.AVIATION /18Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 127 PM EDT Mon May 18 2026

VFR conditions are expected for central Kentucky through this
forecast period. Currently, FEW Cu clouds are streaming over eastern
Kentucky and convective debris clouds are moving into southern
Indiana and northern Kentucky. Gusty winds out of the SSW will
continue through the afternoon. A decaying line of showers and
storms will enter southern Indiana in the next few hours. This will
mostly impact southern Indiana and far northern Kentucky. Storms
will begin to dissipate as the sun sets. Gusty winds will pick back
up out of the SSW on Tuesday morning.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...None.
IN...None.

&&

SHORT TERM...SRW
LONG TERM...BEN
AVIATION...SRW

Special Weather Statement
National Weather Service Louisville KY
521 PM EDT Mon May 18 2026

INZ083-182145-
Dubois IN-
521 PM EDT Mon May 18 2026

...A STRONG THUNDERSTORM WILL IMPACT CENTRAL DUBOIS COUNTY THROUGH
545 PM EDT...

At 521 PM EDT, Doppler radar was tracking a strong thunderstorm 7
miles northeast of Lynnville, moving northeast at 55 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Jasper, Huntingburg, Holland, Dubois, Celestine, Portersville,
Millersport, Dubois Crossroads, Kellerville, and Haysville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3851 8707 3850 8706 3851 8705 3851 8700
      3850 8698 3850 8696 3849 8695 3851 8693
      3850 8691 3850 8688 3853 8683 3853 8681
      3840 8670 3823 8707
TIME...MOT...LOC 2121Z 240DEG 49KT 3826 8717

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

Neudorff

Special Weather Statement
National Weather Service Louisville KY
538 PM EDT Mon May 18 2026

INZ083-084-089-182215-
Crawford IN-Perry IN-Dubois IN-
538 PM EDT Mon May 18 2026

...STRONG THUNDERSTORMS WILL IMPACT SOUTHERN DUBOIS...WEST CENTRAL
CRAWFORD AND NORTHWESTERN PERRY COUNTIES THROUGH 615 PM EDT/515 PM
CDT/...

At 537 PM EDT/437 PM CDT/, Doppler radar was tracking a cluster of
strong thunderstorms over Dale, moving northeast at 40 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Ferdinand, Birdseye, Riceville, Saint Marks, Sassafras, Bristow,
Celina, Bretzville, Mentor, and Saint Croix.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3839 8669 3818 8655 3810 8679 3811 8679
      3812 8681 3812 8680 3815 8681 3816 8680
      3818 8680 3818 8679 3821 8679 3820 8701
      3821 8707
TIME...MOT...LOC 2137Z 234DEG 35KT 3816 8700

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

Neudorff