530
FXUS63 KLMK 171053
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
653 AM EDT Fri Oct 17 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

*  Dry weather and seasonable temperatures are expected today.

*  Warm and windy conditions are expected on Saturday. Wind gusts of
   20 to 30 mph are likely, with high temperatures approaching daily
   records Saturday afternoon.

*  A strong cold front will move across the area late Saturday into
   Sunday morning. There is low confidence in strong or severe
   storms with the front, with strong straight-line winds and a spin-
   up tornado being the primary severe hazards.

*  More windy conditions are likely on Sunday, with 35 to 40 mph
   wind gusts likely.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 351 AM EDT Fri Oct 17 2025

Early this morning, nighttime microphysics satellite imagery shows
scattered high clouds moving into the region from the west. An axis
of sfc high pressure currently extends from the west side of the
Appalachians up into southeast Canada, bringing very light easterly
flow across our area. Temperatures this morning are seasonably cool,
with sheltered valleys falling into the low 40s while urban and
elevated locations are in the upper 40s and low 50s.

Today, quiet weather will continue as an upper ridge axis passes
over the region. Sfc high pressure will slide to the east of the
Appalachians through the day, setting up over the Carolinas by this
evening. This will support winds at the sfc gradually veering to the
SE through the day, with wind speeds generally between 5-10 mph as
the pressure gradient remains relatively weak. Modest SW flow in the
low-to-mid levels later today will begin to bring WAA into KY/IN by
this afternoon, and temperatures should be a few degrees warmer than
yesterday across the area. Expect highs to range from the low 70s
across the KY Bluegrass to around 80 degrees along and west of I-
165.

High clouds will be on the increase through the afternoon, though
filtered sunshine should continue as dry air remains in place from
the sfc to 500 mb. This evening, moisture is expected to build
downward as a subtle H5 wave moves across the OH valley. A larger
mid- and upper-level trough over the northern Plains will continue
to sink southeastward tonight, strengthening the pressure/height
gradient over the region. Accordingly, a steady S/SE breeze should
remain through the overnight hours, which along with mid-level
clouds, should keep temperatures around 10 degrees milder across the
area Saturday morning. Lows should range from the low-to-mid 50s
along and east of I-75 to the upper 50s and low 60s along and west
of I-65.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 351 AM EDT Fri Oct 17 2025

Saturday through Sunday Night...

Moving into Saturday morning, the upper level pattern is forecast to
have broad ridging over the western CONUS with a stout ridge over
the eastern US coast. Across the Plains, a broad mid-upper level
trough axis will be in place. This broad trough axis will shift
eastward during the day on Saturday while strengthening
significantly.

For the daytime hours on Saturday, strengthening pressure gradient
will result in conditions becoming quite breezy/gusty during the
afternoon. Skies will start off mostly sunny during the morning
hours, with an increase in mid-high level cloud cover coming by mid-
late afternoon.  Given anticipated strong southwest flow and
sufficient sunshine, afternoon highs will be well above normal
within the warm sector with highs in the 83-88 degree range. With
these forecast highs, Bowling Green may be able to tie or exceed a
high temperature record set back in 2016 and in other years. For
Lexington and Louisville, current forecast high temperatures are
about 3 degrees below existing records.

For Saturday evening into Saturday night, as upper level trough axis
amplifies, mid-upper level jets are expected to intensify ahead of
the mid-level trough axis. Surface cyclogenesis is expected to occur
over central IN with the low moving and deepening as it heads into
the southern Great Lakes. Trailing cold frontal boundary will
approach the region from the west/northwest. Model plan sections
continue to show a strong low-level jet response with winds of 50-60
kts pushing through the Ohio Valley ahead of the front. Within this
LLJ core, strong IVT approaching the 99th percentile of model
climatology will overspread the area. Moisture plume off the western
Gulf will move into the region with PWATs rising to around 1.7
inches just along the front. The sfc moisture response is a little
more tepid, and seems to be one of the limiting factors for greater
instability, especially east of I-65. Nevertheless, it still looks
like a narrow corridor of low 60s dewpoints should be able to work
in immediately ahead of the front.

During the afternoon hours on Saturday, convection is expected to
develop from the Ozarks up into central IL/IN along the front. As
this initial round of convection pushes east during the evening
hours Saturday, some model guidance tries to bring some of this
activity into southern IN. However, it still looks like the main
line of showers and storms will be just ahead of the cold front,
passing across the region between midnight Saturday night and 8 AM
Sunday morning.

As previous discussions have noted, the dynamics of this system are
strong and wind shear will be more than sufficient for severe
weather, with model progs showing between 45-50 kt of 0-6 km shear
immediately ahead of the cold front. The main limiting factor and
unanswered question will be the amount of available instability.
Typically aggressive progs like the NAM do show around 500-1000 J/kg
MLCAPE from west KY to around the I-65 corridor, creating a classic
high-shear, low-CAPE setup for severe weather. On the other hand,
models which show less instability like the GFS have less than 100
J/kg MLCAPE by the time the line of convection reaches the area,
likely resulting in a decaying line of storms and a diminishing
severe weather threat. If robust convection was still occurring by
the time it reaches our area, the strong wind field aloft and ample
(250-300 m2/s2 0-1 km SRH) low-level helicity would support a
damaging wind and spin-up tornado threat across the area. In short,
there is fairly elevated potential for severe weather with this
system, but low confidence with much uncertainty surrounding the
amount of instability.

Expected rainfall amounts have remained fairly consistent with this
forecast update, with slight downward trends in southern IN. Given
that most of the rainfall should occur within the immediate vicinity
of the front and should be fairly progressive, total rain amounts
are expected to be modest, ranging between 0.75-1.50" on average.
With that being said, locally heavier swaths of rain of 2+" are
still possible, especially within more robust convective cells;
however, widespread flooding issues are not expected with this
system.

Behind the front on Sunday, a strong pressure gradient and strong
flow aloft will lead to windy conditions across the area. During the
morning and early afternoon hours, lingering low-level moisture and
steepening low-level lapse rates will support isolated showers,
with most of the rain chances pushing off to the east by late
Sunday afternoon. BUFKIT momentum transfer progs continue to
show the potential for 35-40+ mph wind gusts during the day on
Sunday, though the amount of lingering low cloud cover leaves
some uncertainty as to how much mixing can occur. If the right
combination of mixing and strong flow aloft overlaps over the
area, a wind advisory may be needed, particularly across north
central KY and southern IN. Temperatures will struggle to warm
within the strong CAA, with the current forecast featuring highs
in the low-to-mid 60s across the area.

Winds will gradually subside as the pressure gradient relaxes Sunday
evening, and clearing skies are also expected. This combination of
lighter winds and clearing skies should allow for temperatures to
tumble as we head into Monday morning, bringing some of the coldest
temperatures so far this season. Lows are expected to range from the
upper 30s to the mid 40s across the area.

Next Week...

The synoptic pattern looks to remain active next week as a series of
shortwave troughs is expected to descend across the eastern half of
the CONUS. The disturbance which will bring the active weather and
cold front through the region over the weekend will be exiting the
northeast US on Monday, with fairly flat upper ridging and sfc high
pressure moving across the southeast US. This should leave us with
slightly below normal temperatures and mostly sunny skies across the
area, with highs in the mid 60s to around 70.

The first of the disturbances to move across the eastern CONUS next
week is expected to descend from central Canada toward the Ohio
Valley Monday night into Tuesday. With medium-range progs trending
faster with this system and depicting fairly flat, broad troughing,
moisture return will be limited. At this time, not expecting more
than isolated to scattered rain showers with this FROPA, followed by
a reinforcing shot of cooler air which should settle into the region
by Tuesday night.

The middle of next week is favored to bring below normal
temperatures as the trough which moves through the region on Tuesday
becomes a closed low over the Great Lakes on Wednesday. There are
minor differences in how close the upper low remains to the Ohio
Valley which could make the difference between more sunshine and
more cloud cover next Tuesday night into Wednesday. Additionally, if
we were to realize more clearing during the middle of next week, low
temperatures in the mid-to-upper 30s and low 40s would be likely
across the area.

Some moderation in temperatures is expected by the end of next week
as the upper low ejects out and is replaced by zonal flow next
Thursday. Another trough/sfc front may try to drop through the
region next Thursday night into Friday; however, confidence is
fairly low at this range given all the systems/atmospheric wave
interactions which will take place between now and then.

&&

.AVIATION /12Z TAFS THROUGH 18Z SATURDAY/...
Issued at 652 AM EDT Fri Oct 17 2025

VFR conditions are expected through the current forecast period with
scattered high clouds this morning gradually increasing in coverage
through the day. Winds will veer to the southeast this morning, with
speeds generally remaining below 10 kt through the day today.
Tonight, clouds will build downward, but ceilings should remain
above 10 kft through the forecast period. Winds will continue to
veer to southerly by the end of the current forecast period, with
stronger S/SW winds expected for the day on Saturday.

&&

.CLIMATE...
Issued at 351 AM EDT Fri Oct 17 2025

Record High Temperatures Possible...

        Sat, Oct 18th
        Rec (Yr) | FCST

SDF     87 (2016) | 84

LEX     87 (1938) | 84

BWG     88 (2016) | 88

FFT     88 (1938) | 84

&&

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

&&

$$

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