Flash Flood Warning 7, NWS Louisville, KY

Area Forecast Discussion
National Weather Service Louisville KY
316 AM EDT Wed May 20 2026

.KEY MESSAGES...

* Periods of showers and storms will move across southern Indiana
  and portions of north-central Kentucky this morning.  Heavy
  rainfall will be possible with localized flooding across southern
  Indiana.

* Another round of showers and storms is expected this afternoon.  A
  marginal risk of strong/severe storms exists across the east-
  central and eastern Kentucky with damaging winds being the main
  threat.

* Busy weather pattern will ramp back up late Thursday and through
  the holiday weekend with episodic bouts of showers/storms with
  heavy, but welcome rainfall.

&&

.SHORT TERM /THROUGH THURSDAY NIGHT/...
Issued at 316 AM EDT Wed May 20 2026

Broad southwest flow continues aloft across the region this morning.
A small perturbation moving northeast within this flow has helped
kick off a persistent band of showers/storms from western Kentucky
into southwestern Indiana.  This corridor of convection is rooted
within the low-level jet axis and also resides in a PWAT plume
extending from west TN northeastward into southern Indiana.  Within
this corridor PWAT values are running in the 1.5-1.9 inch range.

This convection will move off to the northeast through the remainder
of the overnight hours and move across southern Indiana where recent
rainfall has fallen in the last 24-36 hours.  The convection has
generated some cool outflow which is surging eastward toward the I-
65 corridor.  PWAT values do decrease markedly east of the I-65
corridor.  Given that we have some elevated instability in the I-65
corridor and points west, expect this outflow to generate some
additional shower/storms from Hartford northeast through the
Louisville metro over the next few hours.  Shear remains very
marginal here, so severe weather is not anticipated.  However, a
swath of moderate to occasionally heavy rainfall will move across
saturated soils over southern Indiana and may produce some local
hydro issues this morning.  Current flood watch over southern
Indiana continues to look good and no headline changes will be made
with this forecast.

Moving into the daytime hours, surface cold front off to our west
this morning will move into the region this morning and into the
afternoon hours.  As this occurs, another small perturbation aloft
will move northeast across the region and produce another round of
convection across the region.  As the cold front heads eastward
through Kentucky, some diurnal heating will be noted across the
central and eastern portions of the forecast area.  MLCAPE is
forecast to rise into the 800-1300 J/kg range this afternoon.  Model
soundings show rather poor mid-level lapse rates, but the low-level
lapse rates are pretty steep.  That, along with convergence along
the front should allow widespread showers with some embedded
thunderstorms to track across the region.  Some of the storms could
be strong this afternoon, mainly east of the I-65 corridor.  Main
threats will be heavy rainfall and gusty thunderstorm winds. Highs
today will feature a gradient with readings only reaching the low-
mid 70s across the west, with upper 70s to lower 80s out in the I-75
corridor.

Surface cold front is expected to continue eastward this evening
with showers ending from northwest to the southeast into the late
overnight period.  Cool northerly flow will usher in some cooler air
into the region.  Lows tonight will drop into the mid-upper 50s
across southern Indiana with lower 60s across southern Kentucky.

For Thursday, we'll see a brief pause in the wet weather as the
front stalls out to our south.  Blended PoPs keep some chances of
showers down across southern KY, but this looks a bit too aggressive
and I expect those PoPs to decrease over the next few runs.  Highs
on Thursday will be a little cooler than normal with readings only
reaching the lower 70s over southern Indiana and the northern half
of Kentucky.  Mid-upper 70s will be found over the southern part of
Kentucky.  The stalled out front will start to return northward late
Thursday night as a warm front.  Ahead of that warm front, another
round of showers is likely to develop in advance of that feature.
Lows will range from the upper 50s over southern Indiana and northern
Kentucky to the lower 60s over southern Kentucky.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Issued at 316 AM EDT Wed May 20 2026

For the extended portion of the forecast period, unsettled weather
looks likely for Friday and through the Memorial Day weekend as
broad southwest flow will remain in place across the region. Several
weak perturbations aloft will move through the region bringing
episodic bouts/rounds of showers and storms to the region.  Now,
this doesn't appear to be a total washout in all places.  However,
several rounds of showers/storms will be moving across the region
and will bring heavy rainfall, lightning, and gusty winds at times.

The upper level pattern will flatten out a bit by Monday with a
possible split flow pattern developing as we may get a cut off low
to develop over portions of Texas.  Confluent flow east of the
cutoff low across the Ohio Valley will allow a frontal boundary to
remain nearly stationary across the region and this feature will be
a focus of renewed convective development through the end of the
forecast period.  Moisture transport into the region will be high
and PWATs will be running well above climatology here.  So periods
of heavy rainfall are expected.  This rainfall will be welcome to
much of Kentucky that has seen a rather dry period of weather of
late.  QPF amounts of 2-4 inches will be possible across the region
with locally higher amounts in areas that see training.  While much
of this rainfall could see good infiltration into the ground, we
could end up seeing some hydro problems develop in areas that have
seen recent rainfall.

Highs on Friday will generally be in the upper 70s to the lower 80s.
Temperatures for Saturday through Tuesday will see daytime highs
mainly in the lower 80s with overnight lows in the 60s.

Looking past the 7 day period, longer range guidance suggests that
we could see some high latitude blocking redevelop over Canada which
will result in a fairly amplified flow pattern across the CONUS.
There is a pretty decent signal in the data suggesting above normal
rainfall closing out May and heading into early June, though
temperatures look to remain seasonal through this time frame.

&&

.AVIATION /06Z TAFS THROUGH 12Z THURSDAY/...
Issued at 110 AM EDT Wed May 20 2026

For the remainder of the overnight period, conditions will start off
as VFR at the terminals with ceilings gradually lowering toward
dawn.  Scattered convection will be possible, mainly west of a line
from BWG to HNB.  Surface cold front will push through the region
after dawn which will allow winds to shift to the northwest.  As we
move into the late morning hours, an upper level perturbation will
move northeast along the sagging front which will kick off
additional showers/storms, mainly east of a line from BWG to LEX.
Cigs will likely drop into the IFR range with MVFR vsbys due to
rain/storms.  Convective activity will push off to the east toward
the end of the period with IFR cigs remaining in place.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Flood Watch until 2 PM EDT this afternoon for KYZ032.
IN...Flood Watch until 2 PM EDT /1 PM CDT/ this afternoon for
     INZ076>079-083-084-089>092.

&&

SHORT TERM...MJ
LONG TERM....MJ
AVIATION.....MJ