211
FXUS63 KLMK 171120
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
620 AM EST Wed Dec 17 2025

...Updated Aviation Discussion...

.KEY MESSAGES...

* Above normal temperatures expected today and Thursday.

* Gradient wind gusts of 30-40 mph are expected on Thursday ahead of
  a strong cold front.  Widespread showers and a few thunderstorms
  will be possible.  The risk of a stronger storm or two looks
  limited.

* Quick shot of colder air will arrive late Thursday behind the
  front and continue into Friday.  Temperatures will then trend
  warmer through the weekend and into next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 339 AM EST Wed Dec 17 2025

Early morning satellite and observations reveal mostly cloudy skies
across the region.  Temperatures were in the low-mid 40s in many
areas.  The exception has been down in far southern Kentucky where
some clearing has taken place. In those locations, good radiational
cooling has taken place with temperatures falling into the upper
30s/lower 40s.  In the deeper valleys, temps had tanked into the
lower 30s.  For the remainder of the overnight period, generally
cloudy skies are expected to continue.  The lower level stratus deck
may scour out a bit, but plentiful mid-high level cloud cover will
continue to stream northeast across the region.

For today, a weak shortwave trough axis aloft will move across the
Ohio Valley.  With rather limited moisture, especially in the lower
levels, most locations look to remain dry.  Some moisture return may
be sufficient enough to produce a few sprinkles down along the KY/TN
border region.  Southwest winds will continue and modest warm
advection will lead to warmer temperatures.  Highs on the day will
top out in the upper 40s over southern IN and northern Kentucky.
Lower 50s will be seen in areas along and south of the Parkways.

For tonight, mostly cloudy skies are expected across the region.
Warm advective scheme will remain in place and generally much of the
night looks to remain dry.  However, deeper moisture plume will
start to move into the region from the west, a few light rain
showers will be possible toward dawn across our far western CWA.
Overnight lows will range from the mid 30s in the I-75 corridor to
around 40 in the I-65 corridor.  Lower 40s look likely for lows out
in the I-165 corridor and points west.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 339 AM EST Wed Dec 17 2025

Thursday and Thursday Night...

On Thursday, a strong upper level trough axis will move from the
Plains into the Ohio Valley by Thursday Night.  An area of low
pressure is expected to track through the Great Lakes with trailing
cold front that will sweep through the region Thursday evening.

During the day on Thursday, the pressure gradient across the area
will tighten up considerably leading to windy conditions.  Wind
gusts of 30-40 mph will be possible across the region.  Moisture
advection and isentropic lift will lead to widespread showers
developing to the west of the region early in the day and then
spreading into our region during the afternoon hours.  The trailing
cold front is expected to push into the region by late afternoon.

Model soundings continue to show little in the way of surface based
instability with MLCAPE values remaining below 200 J/kg and rather
meager lapse rates.  Overall convective inhibition may be hard to
overcome unless we can get some mid 50 dewpoints in here.  Latest
trends in the model solutions show that this may be harder to come
by as those mid 50 values look to stay south of the KY/TN border. On
the other hand, low-level shear will be quite impressive with 60-
65kts of flow just off the deck.  The best forcing may be the strong
slab forced ascent along the frontal interface.  That forcing may be
enough to get cores tall enough to generate lightning and
potentially mix some of this higher momentum air down to the
surface.  Overall, the risk of severe weather looks to be rather low
in this scenario.  In fact, some models do show a near surface
inversion, which if it develops, would generally keep this line of
stronger convection elevated and not even become rooted at the
surface.  The overall main threat here would be damaging wind gusts
with the strongest cores.  The convective line looks to enter our
western CWA around 3-4 PM EST and then exit the eastern CWA by 8-9
PM EST.  Highs on the day will occur out ahead of the front with
upper 50s/lower 60s expected for high temperatures.  QPF amounts of
0.75-1.00 inch are expected with this system.

For Thursday night, it appears that we may end up with a double cold
front structure with this system. The first front will contain the
aforementioned line of convection with the second front arriving
later in the night bringing the influx of much colder air.  The
modeling is a little faster with clearing precipitation out of here
by late evening while temperatures fall into the upper 30s.  The
second front looks to arrive in the 3-4 AM EST time frame Friday
morning with temperatures falling to the mid 20s.  With the QPF
expected from the Thursday evening convection, there still appears
to be a small risk for a flash freeze Friday morning.  However,
strong, gusty northwest winds are expected in the post frontal wake
which will likely help roads dry out.  This is something we`ll keep
an eye one.  Behind the second front, lapse rates steepen quite a
bit and we could see some snow flurries develop towards dawn.
However, this will be dependent on how much moisture remains in the
DGZ.

Friday through Tuesday...

Friday looks to be mainly dry but a blustery cold day is expected.
Some partial clearing looks to build into the region from the
southwest during the day as high pressure noses into the region.
Under cold advection highs in the low-mid 30s look reasonable across
southern IN and the northern half of KY.  South of the Parkways,
highs in the mid-upper 30s look reasonable.  Dry conditions are
expected for Friday night with lows in the mid-upper 20s.

Over the weekend, the flow aloft continues to trend more zonal in
nature with temperatures rebounding rather quickly.  Highs on
Saturday look to warm back into the lower 50s in the north with mid-
upper 50s down across southern KY.  A fast moving clipper will pass
well north of the region but push a cold front through the area and
may bring some light rain showers Saturday night and Sunday. This
will bring bring down temps slightly on Sunday with highs in the mid
40s over southern IN and northern KY with upper 40s to the lower 50s
over southern KY.

Moving into early next week, some ridging will build across the four
corners region and into the lee of the Rockies.  High pressure will
be centered out to our east across the Mid-Atlantic with a southerly
flow setting up across the region.  A series of weak systems will
continue to move eastward through the Great Lakes and into New
England.  These systems will bring weak frontal waves through the
region resulting in light rain showers being possible Monday and
Tuesday.  Highs Monday will be in the mid-upper 40s in the north
with upper 40s/lower 50s in the south.  Low-mid 50s are expected on
Tuesday in the north with upper 50s to near 60 in southern Kentucky.

&&

.AVIATION /12Z TAFS THROUGH 18Z THURSDAY/...
Issued at 620 AM EST Wed Dec 17 2025

VFR conditions are expected over the upcoming TAF period.  Still
seeing some low stratus out there this morning, but cigs look to
remain VFR.  May see a little bit of gusty winds over at KLEX this
morning, but expect that to abate by mid-morning or so.  Winds will
shift more to the south this afternoon and then to the southeast by
mid-evening.

&&

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

&&

$$

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