692
FXUS63 KLMK 200246
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1046 PM EDT Wed Aug 19 2026

.KEY MESSAGES...

* A cold front pushing into the area from the north tonight will
  bring numerous showers and thunderstorms. A few strong to severe
  storms will be possible, especially west of I-65. Damaging winds
  and localized flash flooding are the main threats with storms.

* Additional low (<20%) chances for showers and storms are possible
  through Saturday night, though most should remain dry after
  Thursday morning. Temperatures should be seasonable to slightly
  below normal through early next week.

&&

.UPDATE...
Issued at 1045 PM EDT Wed Aug 19 2026

Convection has finally started to develop across southern MO this
evening with cloud tops cooling rapidly as ascent spreads into that
area.  Across our region, partly cloudy skies were noted with
temperatures in the lower 70s.

Heading into the overnight, latest CAMs continue to show convection
developing across southern MO and into SE MO.  While a low-level
nocturnal inversion is expected to develop, model soundings upstream
show a broad zone of elevated instability aloft.  Flow aloft is
expected to increase to around 40-45 kts due to the increase in the
nocturnal low-level jet.  Convective activity will gradually shift
eastward into far southern IL and western KY after midnight and then
likely move east-southeast across southern KY during the overnight
hours.  Moisture advection will transport rich moisture into
southern KY with PWATs climbing to 1.8-2 inches.  So the convection
moving out of southern MO will likely train southeast and may bring
excessive rainfall to portions of western and southern KY overnight.
Mesoscale models suggest a swath of 1-3 inch rainfall across our
southern/southwest sections.   This area has missed out on the heavy
rains over the last two weeks and has only seen about 2-20% of
normal rainfall.  So while FFG values are high, training storms
dropping 2-4 inches in a short time can produce flash flooding.
Based on the early 20/00Z guidance, we feel the best chances of
flash flooding would be across our southwest/southern CWA.  So we
have hoisted a short term Flood Watch from Ohio County to Russell
County and points south.  Overall, not overly confident on the
northern edge and eastern edges of the watch as convection is likely
to weaken with eastward extent, especially east of the I-65 corridor.

SPC expanded the slight risk eastward overnight, mainly based on the
potential elevated instability and possible cold pool generation
which could focus a corridor of wind potential across
western/southern KY.  To us, the higher threat looks to remain south
of the WK Parkway and west of I-65, with a diminishing threat as
storms get east of I-65.  Main hazards overnight will be torrential
rainfall, the possibility of some damaging winds
(isolated/scattered) and perhaps some marginal severe hail (very
isolated) in some of the strongest cores.  We do have the low-level
jet providing some speed/directional shear, especially across
western KY where an isolated spinup can`t be ruled out.

Issued at 726 PM EDT Wed Aug 19 2026

Currently seeing partly to mostly sunny conditions early this
evening across the forecast area with temperatures in the upper 70s
to the lower 80s.  Main forecast concern this evening will be
watching convection develop out across southern MO and into SE MO
late this evening with the convection pushing east into KY in the
overnight period.  Current forecast has too high of PoP this
evening, so have gone in and backed off PoPs for the evening hours.

Into the overnight period, confidence in the convective evolution is
still a work in progress.  Instability has been on the increase
across southern MO over the last several hours and we`ve seen some
scattered convection start to develop.  Looking through the last few
runs of the CAMs, they have backed off the convective development a
few hours and really develop things in the 20/01-03Z range.  The
recent CAM signals suggest that we`ll have an instability gradient
set up from southern MO into western/southern KY overnight and that
a possible MCS will develop and trail down that gradient affecting
southern Kentucky.  Generally, we like that idea and have a bit more
confidence with those trends.  Forecast soundings do show an
increasing PBL inversion setting up overnight which may lead to more
of an elevated convective threat, rather than surface based. Though,
given forecast lapse rates and expected shear, robust convection
could linger into the overnight posing a wind and marginally severe
hail threat in the strongest cores.

Heavy/torrential rainfall is likely with this possible MCS across
southern KY.  Expected moisture transport will likely allow PWATs to
surge up to 2 inches or so.  HREF QPF data shows a few swaths of 1-
3" of rainfall with a few localized 4-5" spots, especially where
storms may train over the same areas (or have a boundary get laid
out and have storms repeatedly roll along it).  This area of KY has
largely missed the heavier rainfall from last week, so FFG guidance
is higher down that way.  Nonetheless, some localized flash flooding
will be possible.  If a stronger signal appears in the 00Z guidance,
a short term flood watch may be considered.

Further north, the convective evolution remains uncertain.  Overall
convective trends across southern IN and into the northern half of
Kentucky have been trending downward, though a few CAM solutions
have storms rolling through this region.  Again, with PBL cooling,
we`re likely to see more elevated convection than surface based.
Heavy rainfall, lightning and perhaps some gusty winds would be
possible.  We`ll continue to monitor trends this evening and adjust
the forecast as needed.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 300 PM EDT Wed Aug 19 2026

This afternoon, a band of mainly mid-level clouds and light rain
showers is attempting to move into central KY and southern IN from
the southwest, struggling as it encounters drier air between the
surface and 10k ft AGL. West of I-65, a few light rain showers have
been able to reach the surface, though rain amounts have generally
ranged from a trace to a few hundredths of an inch. East of I-65,
less cloud cover has allowed temperatures to warm into the low-to-
mid 80s, with upper 70s and low 80s observed along and west of I-65.
For the remainder of the afternoon, ongoing showers and clouds to
our west should gradually diminish, with the highest chances (20-
30%) for any additional rain showers expected across southern IN and
west of I-65 in KY.

This evening into tonight, a 500 mb shortwave trough will eject from
the Plains into the mid-Mississippi Valley, moving across the region
during the early morning hours on Thursday. A sfc trough axis
extending across the Ozarks will extend into the Ohio Valley this
evening, serving as an effective cold frontal boundary, with low-
level moisture pooling along and ahead of this boundary.

One of the main forecast questions for tonight is how much moisture
return (and by extension, instability) will be able to extend to the
east-northeast into our area. While short-range progs consistently
show the greatest amounts of MLCAPE (2000+ J/kg) remaining across
western KY and points southwest, some solutions do bring 1000-1500
J/kg of MLCAPE into our western and southwest counties late tonight
into early Thursday morning. Helping to increase instability will be
a 30-35 kt southwesterly jet at 850 mb, with around 15-25 kt of
southwest flow extending down to 925 mb. With that being said, the
warm/unstable sector with this system will be fairly narrow, and
there is the potential that storms diving south across western KY/TN
could cut off the warm sector and reduce the strong/severe storm
potential. While instability is uncertain, deep-layer shear will
likely be strong, especially for August, with around 40-45 kt of
shear expected in the 0-6 km layer. That should allow any robust
convection which develops to be well-organized into several bowing
segments. These bowing segments would bring the main potential for
strong to severe wind gusts, with the highest likelihood for severe
winds expected across southern KY. While a spin-up tornado can`t be
completely ruled out if any segments orient perpendicular to the 0-3
km shear, elevated MLLCLs thanks to pre-existing dry air near the
sfc should limit the overall threat.

Another potential hazard tonight into tomorrow morning would be
heavy rainfall leading to localized flash flooding. Moisture
advection ahead of the cold front should allow PWATs to surge to
around 2" just ahead of the storms tonight. Additionally, any west-
to-east moving lines of storms could leave a residual boundary
resulting in training of showers and storms after the main severe
threat diminishes. In both the 0Z and 12Z HREF 6-hr QPF data, there
are a few swaths of 1-3" for areas especially along and west of I-
65, with hyper-localized amounts as high as 5" showing up. If any of
these solutions with training convection and 3+" of rain occur,
localized flash flooding will be possible.

With the upper wave that is providing a considerable amount of the
forcing moving quickly through the region, the main timing for
showers and storms should be fairly narrow between 10 PM tonight and
8 AM Thursday morning. By mid-to-late morning Thursday, the deeper
moisture and stronger forcing will exit across the Appalachians,
though the sfc cold front will be very slow in moving from north to
south through the area. As a result, pooled low-level moisture
should support continued low-level cloud cover through a good
portion of Thursday, with isolated showers and thunderstorms
possible in the afternoon and evening hours. These storms are
unlikely to be severe, as weaker deep-layer wind shear and forcing
will be much less supportive of organized convection. Highs tomorrow
should be slightly below normal, with most areas reaching the low-to-
mid 80s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 300 PM EDT Wed Aug 19 2026

Thursday Night through Saturday Night...

The remnants of a sfc cold front should sink into southern KY and TN
Thursday night as weak high pressure moves into the Midwest and Ohio
Valley. While this should bring lower PWATs and deep layer moisture
into the region from the north, near-sfc moisture levels are
expected to remain elevated, with sfc dewpoints remaining in the
upper 60s and low-to-mid 70s as we head into Friday. There may be
just enough moisture across southern KY for additional rain chances
Thursday night, but probabilities remain low (15-20%) at this time.
If there is any clearing farther to the north, fog development would
be favored Thursday night given light winds and a moist boundary
layer, and there is already a modest signal on 12Z HREF guidance for
fog Friday morning.

Friday into Saturday, the remnants of the front should dissipate and
push to the south as troughing continues across eastern portions of
the CONUS. Although the air mass should remain fairly muggy, limited
forcing should keep most locations dry Friday into Friday night. A
secondary upper shortwave is expected to drop across Ontario and
into the northeast US Saturday into Saturday night, allowing a
reinforcing cold front to approach the region from the north. While
earlier model guidance suggested this system could bring a chance
for showers and storms, potentially even a few strong storms, recent
guidance has trended farther to the east with the mean trough axis
positioning. As a result, better chances for showers and storms
should remain to the northeast of the region Saturday into Saturday
night, with only isolated chances for showers and storms expected
across southern IN in the current forecast. Temperatures Friday into
Saturday should be near to slightly below normals, with highs in the
mid 80s and lows in the mid 60s.

Sunday through Early Next Week...

As the upper level pattern amplifies over the second half of the
weekend, deepening troughing along the east coast should allow a
cold front to push through the region Saturday night into Sunday.
This front shouldn`t bring much in the way of a cool down; instead,
drier air will be the main feature of the post-frontal air mass,
limiting precipitation chances for Sunday into early next week. LREF
guidance shows ensemble mean PWAT values below climatological norms
Sunday into Monday, with dewpoints in the upper 50s and low-to-mid
60s returning to the area.

As we head deeper into next week, a NW flow pattern should continue
across the Ohio Valley, with ridging trying to extend into the
Plains while troughing continues across the eastern seaboard. This
pattern could bring the potential for transient systems to ride
along the edge of the upper ridge, bringing a chance for showers and
storms, though at this time, the strongest signal in guidance for
these systems is to the southwest of the area.

&&

.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 748 PM EDT Wed Aug 19 2026

VFR conditions and light SW winds will continue this evening. In the
early overnight, a cluster of storms moving ESE across KY will bring
gusty winds and brief drops in visibility. Showers will be around
for a few hours as the wave of storms rolls to the east. BWG may see
the strongest wind gusts from any storms overnight. After the
showers and storms roll through, a front will approach from the NW
shifting winds from out of the SW, to out of the NNE by Thursday
afternoon. Along with this shift in wind directions, temporary drops
in ceilings to low end VFR-high end MVFR are possible, with HNB
experiencing the lowest ceilings. Once the front sweeps through each
terminal, VFR conditions will return Thursday afternoon with a light
NNE wind.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...Flood Watch until 7 AM CDT Thursday for KYZ026-027-061>064-
     070>078-081-082.
IN...None.

&&

$$

UPDATE.......MJ
SHORT TERM...CSG
LONG TERM....CSG
AVIATION.....BKF