260
FXUS63 KLMK 171112
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
712 AM EDT Thu Jul 17 2025

.KEY MESSAGES...

* An active weather day is expected across the region with scattered
  to numerous showers and thunderstorms expected this afternoon and
  evening.  Storms could have strong downburst/microbursts resulting
  in localized damaging winds.

* Torrential rainfall is expected with the storms this afternoon and
  flash flooding may occur. The highest risk of flash flooding will
  be across SE Indiana and into the Bluegrass region.

* Outside of storms, near advisory levels of heat/humidity are
  expected with afternoon heat index readings reaching the upper 90s
  to the lower 100s.

* A continued active pattern continues into the weekend and early
  next week, with daily chances for showers and storms. Hot and
  humid weather is also expected to continue.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 711 AM EDT Thu Jul 17 2025

Earlier convection has diminished across the region.  In the wake of
the evening convection, skies were clear to partly cloudy across the
region with temperatures in the low-mid 70s.  Winds remain light
across the region which will likely limit overall fog formation with
the exception of the protected valleys.  Through sunrise, no
significant weather is expected with temperatures remaining in the
low-mid 70s.

For today, a rather active day of weather is expected.  A weak
surface cold front will drop into the I-70 corridor this morning and
it probably will not make it much further south during the day.  To
the south of this boundary, a rather convergent low-level flow will
draw ample moisture into the region with surface dewpoints remaining
in the low-mid 70s.  With insolation during the morning, we`ll see
ample instability develop with scattered showers and storms expected
to fire by late morning.  A gradual upscale growth into multiple
clusters is expected.  While instability will be fairly high across
the region (3500-4500 J/kg), deep layer shear continues to look less
than 20kts.  Very warm cloud depths are expected once again, so
water loaded downdrafts producing strong gusty winds and intense CG
lightning will be the main severe threats.  With PWATs remaining in
the 2.1-2.2 inch rain, torrential rainfall is expected with these
storms.  The good news is that the environmental flow will keep
storms moving, however, storms may have a tendency to train across
portions of the region and that could produce some flooding issues.

Looking at the last few days of rainfall across the state, most
areas have seen rainfall, but there have been a few corridors where
locally heavier rainfall has been observed.  Tonight`s datasets
continue to suggest heavier rainfall across SE Indiana and down into
the Bluegrass region.  This area has seen some good rainfall in the
last 24-36 hours.  After coordinating with surrounding offices,
we`re going to hoist a Flood Watch across our NE sections with
ILN/JKL for this afternoon/eve activity.  This area is where we
currently thing that flash flooding may be most concentrated.

Outside of the rainfall/storm threat, it will be a rather hot/humid
data across the area with highs in the upper 80s/lower 90s.  Those
temps combined with dewpoints in the low-mid 70s will likely produce
heat indices in the upper 90s to the lower 100s.  Confidence here
for meeting criteria is low because it is possible that convective
coverage may foil our afternoon heating and potentially limit
heating in some areas.

For Tonight, ongoing convection should be in progress this evening
across the area.  Convection should diminish after sunset with the
loss of heating.  With the front remaining north of the region,
overnight lows will only drop into the lower-middle 70s.  With the
expectation of convection diminishing around midnight, we`ll let the
flood watch go until then.  However, there is some signaling in the
guidance that additional shower/storms may develop later in the
night.  Should that occur, an extension of the flood watch may be
required in subsequent forecasts.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 711 AM EDT Thu Jul 17 2025

Remnant frontal boundary will remain just north of the region on
Friday and a tropical airmass will remain in place across the
region.  Given anticipated convective coverage Thu/Thu night,
lingering convective cloud debris will likely be noted across the
region on Friday keeping high temperatures in the upper 80s to near
90.  Shear across the region will remain rather weak, but we`ll see
the typical diurnal increase in instability across the region which
should support at least scattered convection once again.  Mainly
pulse-type storms are expected with waterloaded downdrafts, though
overall coverage may be a bit more limited on Friday with less
instability and lack of focused forcing.  Heavy rainfall with storms
will be possible as PWATs remain at/above 2 inches.  Lows Friday
night will drop back into the low-mid 70s.

For the weekend and into next week, the upper level pattern is not
expected to change much.  The SE ridge looks to remain entrenched
across the area with perhaps a slight retrogression to the west.
Slight ridging may take place across the Plains which will result in
a more northwest flow regime across the Ohio Valley.  Multiple
perturbations moving through within the flow pattern will likely
produce episodic bouts of convection.  Model soundings through the
period continue to show rather weak shear, but ample diurnal
instability developing.  With a tropical airmass remaining in place,
heavy rainfall with storms will remain a threat.  The northwest flow
pattern could result in multiple MCSs that could drop down into the
region.  Current thinking is that northern IL/central IN and down
into northeast/eastern KY could see the most convective action here
along with a threat of flash flooding.

Outside of storms, it will remain hot and muggy with daytime highs
in the upper 80s to around 90 and overnight lows in the low-mid 70s.

&&

.AVIATION /12Z TAFS THROUGH 18Z FRIDAY/...
Issued at 711 AM EDT Thu Jul 17 2025

Generally VFR conditions are expected this morning and into the
afternoon hours with a light southwest wind expected.  As we move
into the afternoon, expect scattered showers and storms to become
more numerous across southern Indiana and north-central Kentucky.
Have tried to add some tighter timings in here for storms this
afternoon with this forecast package.  Current thinking is that best
times for storms at HNB/SDF/LEX/RGA will be in the 17/20-24Z time
frame.  Look for tempo drops to IFR in storms with wind gusts of 30-
35kts if a storm was to impact the terminal.  Coverage down in the
BWG area is a little more uncertain so have continued PROB30s down
there for the 17/20Z-18/01Z time frame.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Flood Watch from 2 PM EDT this afternoon through this evening
     for KYZ031>043-047>049-055>057-067.
IN...Flood Watch from 2 PM EDT this afternoon through this evening
     for INZ079.

&&

$$

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