503
FXUS63 KLMK 232317
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
617 PM EST Sat Nov 23 2024

...Updated Aviation Discussion...

.KEY MESSAGES...

*  Low clouds continue to slowly clear from southwest to northeast
   through the evening hours.

*  Rain showers are likely Monday with a cold frontal passage.

*  Another round of rain showers is likely for Wednesday and into
   Thanksgiving Day, with colder conditions arriving Thursday night.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 339 PM EST Sat Nov 23 2024

For the rest of the day, surface high pressure over the Tennessee
Valley will continue to get pushed eastward. This is causing winds
over the CWA to back from the west towards the south, and as this
happens warm air advection is going to increase. Winds will remain
light, as we sit so close to the surface high. This is helping to
dissipate the stratus deck that remains over southern Indiana and
all but the far southwestern parts of central Kentucky, south of
Bowling Green. This is expected to be a slow process as the clearing
works towards the northeast through the evening hours.

Tonight, winds continue backing towards the south with ceilings
slowing clearing to the north. Light winds and clearing skies will
help radiative cooling which could help lead to a few patches of
fog, but fog is looking less likely than it was early as the stratus
could be replaced with some high level cloud cover later tonight.
The best chance for fog would be across southern Kentucky where
sooner and more clearing is expected, but still not expecting fog to
become widespread. Most places will see lows in the mid 30s to near
40. Some in the far southeastern parts of the CWA, in and around
Clinton County, could see the low 30s.

Tomorrow, as the next low pressure system over the PLains advances
eastward towards the Lower Ohio Valley, gradient winds will begin
increasing. WAA under mostly sunny skies will help push highs into
the mid 50s to low 60s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 339 PM EST Sat Nov 23 2024

Sunday night - Monday night...

An upper level shortwave trough is forecast to swing east across the
central Plains, Midwest, and Great Lakes/Ohio Valley Sunday night
through Monday night. Sfc low pressure is forecast to lift northeast
from the Plains across the Great Lakes during this time frame,
dragging a cold front through central KY and southern IN Monday
evening.

Sunday night continues to look dry and mild. Strengthening low-level
SW flow will advect warmer air into the region, but much of the
column will remain dry. We will likely see increasing cloud cover
early Monday morning, however. It appears overnight lows will occur
earlier in the night, rather than around sunrise as is typical. Lows
should range from the low/mid 40s in the Bluegrass to the upper
40s/near 50 elsewhere.

Low to mid-level saturation takes place Monday morning into the
afternoon ahead of the approaching cold front. Moisture availability
for this system is not spectacular, with PW values briefly peaking
above 1 inch Monday afternoon and evening. A few light showers will
be possible Monday morning, especially in southern IN. More
widespread light to moderate rain looks likely Monday afternoon and
evening, with light rain tapering off Monday night.

Expect mild conditions Monday, with afternoon highs in the low to
mid 60s. Rainfall totals of 0.10-0.25 inches will be possible
through Monday night. Much cooler, drier air floods the region
behind the front. After precipitation departs, expect temps to drop
into the low to mid 30s Tuesday morning.

Tuesday - Tuesday night...

This period looks cool and dry. Benign zonal flow will be found
aloft as sfc high pressure slides from the Ozarks across the Ohio
Valley. While clouds should continue to gradually clear Tue morning,
expect a chilly day with highs in the mid/upper 40s. Lows Tuesday
night should be in the upper 20s to mid 30s, with less efficient
radiational cooling 06-12Z Wed due to increasing high clouds.

Wednesday - Friday...

Wednesday, low pressure organizes over the southern Plains as an
upper level shortwave trough drops southeast over the Rockies and
High Plains. The day is likely to start off dry, but rain chances
increase through the second half of the day with increasing WAA and
isentropic ascent across a warm front. Though the exact track and
strength remains uncertain, low pressure is forecast to lift
northeast across the Lower OH Valley Wednesday night into Thursday
morning.

This should produce a rainy start to Thanksgiving Day. This system
eventually pulls away to the ENE Thursday night, with cold air
wrapping into the region from the NW. Cannot rule out a brief
changeover to light snow late Thursday or Thursday night before
deeper moisture departs the region. However, the better chance for
accumulating snow is certainly to our north across central IL/IN/OH.

Temperatures during this period are tricky and will exhibit
a north to south gradient. As of now, highs on Wednesday look to
range from the mid 40s to lower 50s, but this will ultimately depend
on the detailed evolution of the low pressure system. Temperatures
on Thanksgiving Day may not budge much from the low to mid 40s,
making for a potentially nasty, wet day. Temperatures are then
forecast to drop to near or below freezing by Friday morning.
Conditions may trend drier for Friday, but expect a chilly day with
highs in the upper 30s to lower 40s. Some cold nights will then be
possible next weekend, with lows in the 20s.

&&

.AVIATION /00Z TAFS THROUGH 06Z MONDAY/...
Issued at 617 PM EST Sat Nov 23 2024

Current satellite imagery shows stratus layer quickly lifting
southwest to northeast across the forecast area; therefore, MVFR
conditions are reflected tonight at all terminals with moderate to
high confidence in timing. In addition, upper clouds are noted
moving in from the Midwest which could prevent/limit radiational fog
formation, especially along the northern terminals. Low-end VFR
visibility due to patchy, shallow fog is indicated at BWG to account
for a longer time with clear skies. For tomorrow, dry weather with
light southerly winds.

Extended Outlook...The leading edge of a LLJ extending across the
Mid Mississippi could support LLWS conditions Sunday night.

&&

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

&&

$$

SHORT TERM...KDW
LONG TERM...EBW
AVIATION...ALL