996
FXUS63 KLMK 181723
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
123 PM EDT Sat Oct 18 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

*  Warm and windy conditions are expected today. Wind gusts of 20 to
   25 mph are likely, with high temperatures approaching daily
   records.

*  A strong cold front will move through the region late tonight .
   into tomorrow morning. A strongly forced line of showers and
   thunderstorms is expected. Some storms could be strong to severe
   with damaging winds being the primary hazard.  However, a spin-up
   tornado can not be ruled out in areas west of I-65.

*  Cold front will slice through the region Sunday morning, with
   showers lingering through the day. Gusty winds are expected
   through the day with gusts of 30 to 40 mph.

*  Drier and much cooler weather is expected for much of next week,
   with a small shower chance Monday night. Frost will be possible
   Wednesday and Thursday mornings, especially in the Bluegrass
   region.

&&

.UPDATE...
Issued at 1040 AM EDT Sat Oct 18 2025

Morning satellite imagery reveals mostly sunny skies across
southern Kentucky with partly cloudy skies across much of western
Kentucky and southern Indiana.  Weak isentropic lift has resulted in
a few light showers across southwest and west-central Indiana this
morning.  Some of the CAMs were picking up on this.  This activity
should continue to move to the northeast through the morning.
However, will do a quick update to add some slight chance PoPs
across portions of Dubois/Orange/Washington counties of southern
Indiana for a few hours.  Remainder of the forecast here looks
pretty good for the afternoon with breezy conditions (wind gusts 20-
25 mph) and highs in the 83-88 degree range.

Wanted also to touch on the potential for a period of gusty winds
overnight.  For the past several days we`ve been highlighting the
risk of strong storms moving into the region from the west tonight
that could produce some damaging winds in spots, especially where
stronger cores are present.  However, it is looking more likely that
we`ll see a period of gusty winds just ahead of the showers/storms
as they move in late tonight.

06Z and 12Z HRRR solutions continue to show the low-level jet
ramping up after sunset with a pretty good core of higher momentum
air setting up just off the deck.  Model soundings show an inverted
V profile indicative of drier air in the low-levels just ahead of
the advancing convective line.  As precipitation starts to fall
through this dry layer, we may be able to mix down some of that
higher momentum air and a period of gusty winds (45-50 mph) could
occur in advance of the rain.  Once the rain starts over a location
and saturates the profile downward, the momentum transfer will be
much more muted.  I`ve seen in this several times in the past couple
of years here where we had a period of very gusty winds just on the
front side of an advancing line of showers/storms.

We`re going to continue to look through the remainder of the 12Z
high resolution datasets, but I suspect that we may hoist a Wind
Advisory late tonight across portions of the region to address this
period of potentially high wind gusts.  Once this well advertised
front pushes through Sunday morning, we`ll see a lull in the winds
during the morning hours, but another round of gusty winds will be
possible in the afternoon.  Although, much of the guidance has
trended downward on wind gusts for Sunday afternoon due to an
increase in cloud cover which may limit downward momentum transfer
due to more muted mixing.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 401 AM EDT Sat Oct 18 2025

Early this morning, a subtle upper-level shortwave is moving across
the Ohio Valley within broader SW flow. This wave has brought
scattered to broken mid- and high-level clouds over the past 12-18
hours, with the back edge of these clouds expected to clear the area
by mid-morning. Temperatures are currently exhibiting a pronounced
ridge-valley split, as more exposed locations currently have a light
S/SE breeze keeping temperatures milder while valley locations are
still able to decouple. Current readings as of 07Z range from around
50s in the coolest locations to the low-to-mid 60s in the warmest
areas. Temperatures should remain fairly steady between now and
sunrise.

Today, warm and breezy conditions are expected across central KY and
southern IN as deep SW flow settles in between a departing upper
ridge and an approaching upper trough. H85 flow of around 20-30 kt
through the day will allow for some stronger wind gusts to make it
to the sfc. Fortunately, the area which is expected to see less
cloud cover and deeper mixing will also have slightly weaker flow
aloft, and vice versa, so most locations should see peak wind gusts
in the 20-25 mph range, with a few 30 mph gusts. Low-level veering
of winds will support strong WAA, with the only limit on heating
today being increasing cloud cover from the NW this afternoon. Near-
record high temperatures are expected this afternoon, particularly
at BWG, with many areas south of the WK/BG Parkways warming into the
mid-to-upper 80s. Areas farther north and west should top out in the
low-to-mid 80s.

Over the next 18-24 hours, an initially complex area of broad upper
troughing over the north central CONUS will consolidate into a
highly-amplified wave as shortwaves ejecting out of the Rockies and
southern Plains this morning merge into a single wave by the time it
reaches the Miss. Valley Sunday morning. While there should be
enough of a mid-level cap to keep most of the area dry through the
daytime hours today, height falls to the immediate NW of the region
may be sufficient for a few storms to sink into our southern IN
counties during the late afternoon and early evening hours, as
depicted in several of the 00Z hi-res models. This time period would
have the best instability, with HREF mean SBCAPE between 500-1000
J/kg and max SBCAPE approaching 1500 J/kg. While wind shear won`t be
as strong as overnight tonight, 35-40 kt of deep-layer shear should
keep storms organized, though soundings suggest most of that should
be speed shear.

The more widespread threat for showers and thunderstorms is expected
late tonight into Sunday morning as the cold front and the main
upper trough axis swings across the region. A 100+ kt H5 jet will
descend across the MO River basin late tonight, with strong upper
diffluence expected ahead of the trough axis. Low-level response
will lead to the development of a 55-60 kt LLJ across the Ohio
Valley tonight, providing ample wind shear for convective
organization, as well as bringing greater Gulf moisture up into the
region. Immediately ahead of the front, PW values should surge to
1.6-1.7", exceeding the 95th percentile of climatology. While a
corridor of low-to-mid 60s dewpoints will move across the region
immediately ahead of the main convective line, instability is still
expected to be limited, especially as you go east of the I-65
corridor. HREF mean CAPE progs are only around 100-300 J/kg, with
maximum CAPE values only approaching 500 J/kg. In contrast, shear
will be strong as mentioned above, and model hodographs do depict
good low-level curvature, with 200-300 m2/s2 0-1 km SRH.

Most hi-res models show a line of thunderstorms moving across the
Miss. Valley this evening, reaching our western CWA border around or
just after midnight. As this line moves from western KY and southern
IL into central KY and southern IN, a gradual lessening of
convective intensity is expected as storms encounter a more stable
environment. The main forecast question is will convection still be
strong enough as it crosses into our region to either get strong
winds aloft down to the surface or to get quick spin-up tornadoes
thanks to the strong low-level helicity. As it stands, the overall
severe threat for tonight is low, but strong straight-line winds and
a spin-up tornado are possible.

While brief heavy rainfall rates are likely tonight into tomorrow
morning, the progressive nature of this system and lack of robust
convection should keep rain totals low enough to preclude flooding
concerns. While basin average rainfall amounts of 0.50-1.25" are
expected, HREF LPMM values indicate the potential for up to 1.5-2"
in narrower swaths.

Showers should continue along and immediately behind cold FROPA
during the day on Sunday, with low-level lapse rates steepening
behind the front. There is some potential for low-topped convection
bringing strong wind gusts across the Bluegrass during the morning
on Sunday, which is likely what has prompted the Day 2 marginal
risk. Gradient winds will remain strong throughout the day on Sunday
as strong CAA overspreads the area. There is more uncertainty now as
to whether we will be able to get enough mixing to get advisory
level wind gusts on Sunday, as models have trended toward more cloud
cover and showers during the peak heating window. Still think that
widespread 30-35 mph wind gusts are a good bet, with isolated 40+
mph gusts possible. Temperatures will likely be stuck in the 50s and
low 60s through the day thanks to the aforementioned CAA and cloud
cover.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 401 AM EDT Sat Oct 18 2025

By Sunday evening, the upper trough associated with the active
weather over the weekend will already be ejecting to the northeast
across the Appalachians as sfc high pressure builds into the Gulf
states. Skies should continue to clear from west to east, and winds
should gradually subside overnight as the pressure gradient weakens.
With the cooler air mass now overhead, temperatures should easily
fall into the upper 30s and low-to-mid 40s Monday morning.

For the day on Monday, a progressive synoptic pattern will cause
flat upper ridging and the sfc high pressure over the Gulf states to
quickly slide to the east, with warmer return flow beginning across
the area by Monday afternoon. As height falls occur to the NW of the
region with another approaching trough, breezy SW winds should help
send temperatures recover into the mid-to-upper 60s and low 70s
Monday afternoon under mostly sunny skies.

The upper trough should descend from the northern Plains toward the
Ohio Valley Monday evening into Tuesday morning, bringing another
sfc cold front through the region. The track and relatively un-
amplified nature of the system will limit its ability to tap into
Gulf moisture, and PW anomalies along and ahead the cold front are
unimpressive. As a result, while a few showers will be possible as
the cold front passes Tuesday morning, the more noteworthy sensible
weather impacts will be the wind shift as gusty westerly winds are
expected through the day on Tuesday. As the upper low pivots over
the Great Lakes Tuesday night into Wednesday, it may be just close
enough to our area to bring increased cloud cover across the
northern CWA through Wednesday. Regardless, continued CAA Tuesday
night into Wednesday should bring the coolest temperatures of the
season thus far during the middle of the week, with highs in the low-
to-mid 60s and lows in the upper 30s and low 40s. Sfc high pressure
moving across the region Wednesday night into Thursday should bring
the best radiational cooling conditions, and this period has the
best chance of frost during the current outlook period.

For the latter portion of next week, digging troughing off the
Pacific coast should allow for ridging to build over North America,
though there is some suggestion in medium-range guidance of split
flow with a cutoff low meandering over the central Plains into the
Mississippi Valley next Thursday into Friday. Temperatures are
expected to moderate somewhat, though the magnitude of warming is
uncertain given the potential for clouds/showers associated with the
cutoff low.

&&

.AVIATION /18Z TAFS THROUGH 00Z MONDAY/...
Issued at 122 PM EDT Sat Oct 18 2025

VFR conditions are expected this afternoon with breezy south to
southwest winds.  Cu field is expected along with some mid-high
level cloud cover.  Wind gusts of 18-20kts will be possible through
the afternoon with winds slacking off toward sunset.  Could still
see a stray shower at KHNB late this afternoon and evening, though
most locations should remain dry through at least 19/04Z.

Overnight, a strong cold front will push through the region.  Ahead
of the cold front, a low-level jet will overspread the region
resulting in LLWS at all the terminals.  Winds will be primarily
from the south at 10-12kts with gusts to 25kts being possible.
Showers and a few thunderstorms look to cross the terminals between
19/05-13Z.  Some locally higher gusts to 35-40kts can`t be ruled out
on the front edge of the line of showers and with embedded heavier
storms.  Cold front should clear KHNB by 19/10Z, KSDF/KBWG by 19/12Z
and KLEX/KRGA by 19/13-14Z.  Expect MVFR cigs behind the front with
gusty west to west-northwest winds through the afternoon on Sunday.

&&

.CLIMATE...
Issued at 401 AM EDT Sat Oct 18 2025

Record High Temperatures Possible...

        Sat, Oct 18th
        Rec (Yr) | FCST

SDF     87 (2016) | 84

LEX     87 (1938) | 83

BWG     88 (2016) | 88

FFT     88 (1938) | 84

&&

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

&&

$$

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