431
FXUS63 KLMK 181723
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1223 PM EST Tue Nov 18 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

* Widespread rain and scattered storms continue through late this
  evening. Through late afternoon, the main threat from strong
  storms will be small hail and heavy rain. This evening, there is a
  narrow window for an isolated spin-up tornado across western and
  southern portions of the CWA.

* Active weather pattern will bring additional chances for rainfall
  Thursday through Saturday.

* This weekend through early next week continues to trend drier.

&&

.UPDATE...
Issued at 949 AM EST Tue Nov 18 2025

Earlier band of convection continues to weaken and push eastward
through the Bluegrass region of central Kentucky this morning.
Surface analysis shows our warm front extending NW to SE from
Henderson, KY down to near Tompkinsville.  To the northeast of this
line, temps were in the upper 40s with lower 40s over the Bluegrass
region.  Out west of this line, temps were in the lower 60s, though
some mid 60s were down in far SW near Fulton.

Regional radars show a NE-SW oriented line of convection extending
from roughly Bloomington IN southwest through Paducah.  The
convection over SW IN is elevated in nature, but the convection out
across far western KY is likely more surfaced based.  We expect this
line to move eastward throughout the day.  Locally heavy rainfall,
lightning, and small hail will be possible with this activity.  The
more surfaced based activity may be able to produce dime/nickel
sized hail as it moves through western KY.

For the afternoon hours, convective evolution remains a bit unclear.
The main forecast challenge here will be how far north will the warm
front lift this afternoon.  Additionally, questions on instability
remain as abundant cloud cover will likely mute afternoon heating.
However, despite the cloud cover, low-level theta-e advection may be
able to offset that a bit and lead to some surface based instability
south of the warm front.  Warm frontal position will be critical on
determining where the main severe threat will be.  It is possible
that the warm front could lift as far north as the I-64 corridor
late this afternoon/evening.  Anywhere south of that front is where
storms have the best chance of becoming surfaced based.  The wind
profiles along the boundary will be more than sufficient for
supercell structures capable of all hazards.  Just looking through
the early 12Z CAMs and some of the early machine learning CAMs,
think the Marginal is placed well, though if enough forecast
confidance can be achieved, a slight risk could be introduced from
SW into the western third of KY later today.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 348 AM EST Tue Nov 18 2025

This morning, a compact H5 closed low is ejecting out of the central
Plains and is expected to cross the Mississippi Valley later today.
An associated sfc low just to the southeast of this mid-level
disturbance will likewise move to the east across the mid-
Mississippi Valley today, with the mid-level low expected to
overtake the sfc low as it moves across the Ohio Valley this evening
into tonight. Ahead of the main mid-level wave, strengthening SW low-
to-mid level flow is promoting warm air and moisture advection, with
isentropic lift over a near-sfc cool and dry air mass helping to
force scattered rain showers through the morning, especially across
northern KY and southern IN.

As we head through the morning and into the early afternoon hours,
continued warm advection will gradually erode the near-sfc cool and
dry air mass from south to north across the region. Temperatures
across southern KY are likely to jump into the upper 60s and low 70s
this afternoon. With the mid- and upper-level wave being relatively
flat as it moves into the region, and persistent low clouds and rain
showers to the north of the effective warm front later today, it is
expected that the warm front will struggle to push much to the north
of the I-64 corridor by late this afternoon and into the evening,
though forecast confidence in the exact position of the front is
only medium at best. As a result, it is likely that we see an
unusually strong SW-NE temperature gradient over the CWA today, with
portions of southeast IN and the KY Bluegrass struggling to reach 50
degrees.

With the H5 low approaching the region later today, height falls
aloft combined with low-level WAA should lead to steepening mid-
level lapse rates and increasing elevated instability. By mid-
afternoon, HREF mean MUCAPE is at least a few hundred joules across
the CWA, with MUCAPE approaching 1000-1500 J/kg west of I-65.
Through mid-to-late afternoon, dry air in the lowest 1 km should
keep convection elevated across the area, with the main hazard from
strong thunderstorms being heavy rain, lightning, and small, likely
sub-severe hail.

A plume of upper 50s and low 60s dewpoints is progged to attempt to
work into western KY and SW IN by around sunset this evening,
introducing the potential for sfc-based convection. At the same
time, the sfc frontal wave will begin to sag south through the
region, with the front along with strong mid-level CVA providing
ample forcing for ascent. This will effectively "pinch off" the zone
for sfc-based convection from NW to SE as the frontal band of
showers and storms moves through the area. Where sfc-based
convection is able to develop, ample deep-layer shear and llvl
hodograph curvature will be sufficient for all convective hazards,
including hail, damaging winds, and spin-up tornadoes. Where
convection remains elevated farther to the north and east, any
stronger updrafts could produce isolated severe hail, along with
gusty winds. Looking at a combination of model soundings and AI/ML
severe convection guidance, it looks like the best chance for the
all-hazards, sfc-based convection threat will be southwest of a line
from Jasper to E-town to Russell Springs, though confidence in this
is only medium. The most impactful severe timing is expected to be
immediately ahead of cold FROPA, between roughly 6 PM EST (northern
CWA/southern IN) and Midnight EST (southern CWA/TN border).

While it is a secondary threat, locally moderate to heavy rainfall
amounts are likely between now and Wednesday morning, as PWAT values
should increase to 1.2-1.4" this afternoon and evening. While decent
CAPE profiles and shallower freezing levels likely limits efficient
collision-coalescence processes, individual convective cells will
still put down heavy rainfall swaths. 0Z HREF 24-hr LPMM does show a
few swaths of 2+" QPF between now and 06Z Wednesday, mainly along
and north of I-64. Still, this is amount of rainfall is not expected
to cause more than localized nuisance flooding and ponding of water
on roadways.

By late tonight, AVA aloft combined with post-frontal subsidence
should bring an end to precipitation chances, especially after
around 2 AM EST. However, llvl moisture is expected to stick around
into Wednesday morning, with low stratus overspreading the area.
Sounding profiles suggest that the stratus will be fairly thin;
however, it could be just deep enough to get some patchy mist or
drizzle behind the sfc cold front. Temperatures are expected to
remain mild into Wednesday morning, with lows ranging from the mid
40s to near 50 north of I-64 to the mid-to-upper 50s along the TN
border.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 348 AM EST Tue Nov 18 2025

Wednesday through Saturday...

In the wake of the disturbance which will move through the region
later today into tonight, broad, flat ridging is expected across
much of the eastern half of North America during the second half of
the week. A cutoff low extending from the Great Basin down to Baja
California is expected to remain out of phase with the northern
stream wave pattern for the foreseeable future, with the center of
the low staying over the southwest US and northern Mexico into early
next week. However, while the center of the upper low will remain
well to the west, smaller shortwaves and vorticity lobes are
expected to eject eastward within strongly baroclinic, zonal flow
later this week, bringing the next chance for widespread rain into
the Ohio Valley.

On Wednesday, we should still have broad subsidence over the region,
with time heights showing a deep layer of dry air above 850 mb.
However, trapped llvl moisture should keep stratus overhead, leading
to overcast skies for most of the region. While most will remain dry
Wednesday into Wednesday night, there could be a stray sprinkle or
light shower within the shallow stratus layer. With the washed out
sfc front near the area, a strong north-south temperature gradient
is expected, and confidence in exact high and low temperatures is
fairly low.

Thursday into Thursday night, the first of several late week
disturbances will move from west to east along the residual sfc
front over the area. Rain chances should increase from west to east
during this period as mid-level shortwaves induce stronger SW low-to-
mid level flow and increasing PWATs. Additional rounds of rain will
move across the region Friday morning through Saturday morning as
the mid- and upper-level flow pattern keep the "train tracks" in
place over the Ohio and Tennessee valleys. Since there won`t be a
well-defined upper trough to move through the region, it appears
unlikely that there will be enough instability for strong storms;
however, a few embedded thunderstorms can`t be ruled out during the
late week period. Rain chances should begin to diminish on Saturday
as the final piece of mid-level energy ejects across the region,
with ridging starting to build again Saturday night into Sunday.
From Thursday through Saturday, current most likely rainfall amounts
range from 1-2" across the area, and while the ground will become
increasingly saturated, significant hydro issues remain unlikely.

Saturday Night into Early Next Week...

Forecast confidence is still relatively low by the end of the
current extended forecast period; however, there is increasing
likelihood that the second half of the weekend into early next week
will be mostly dry. With no strong trough/frontal passage expected
behind the late week precipitation, temperatures will remain fairly
mild/seasonable into early next week, with highs in the upper 50s
and low 60s and lows in the upper 30s and low 40s Saturday night
through Monday night.

&&

.AVIATION /18Z TAFS THROUGH 00Z THURSDAY/...
Issued at 1223 PM EST Tue Nov 18 2025

Surface warm front is along and just north of I-64 this afternoon.
A SW-NE band of showers and embedded thunderstorms is working across
central Kentucky at this time and will primarily affect LEX/RGA/BWG
this afternoon.  Gusty winds will be seen across southern KY
including KBWG.  Additional convective redevelopment is expected
across SW IN and western KY this afternoon and will push eastward
across the region late this afternoon and this evening.  Surface
cold front will then plow through the region ending showers/storms
from NW to SE.  Behind the front, IFR to LIFR cigs will build down
across the region.  A good signal of fog is showing for KLEX/KRGA
later tonight, though we`ll continue to watch for that fog signal in
the BWG area as well.

&&

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

&&

$$

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