854
FXUS63 KJKL 152327
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
627 PM EST Mon Dec 15 2025

.KEY MESSAGES...

- Near normal, to above normal, temperatures are expected from
  Tuesday through the end of next week with the exception of
  Friday.

- Multiple systems are expected to bring mainly rain chances late
  Wednesday into early Friday, and again Saturday night into early
  next week.

&&

.UPDATE...
Issued at 542 PM EST MON DEC 15 2025

A quick late afternoon/early evening update has been sent out to
update the grids with the latest hourly temperature observations.
Otherwise, the forecast is on track with no changes.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 340 PM EST MON DEC 15 2025

Tonight and Tuesday, the upper low currently over the Maritimes
vicinity and associated trough into the western Atlantic will
depart further to the north and east while the axis of an upper
level ridge is progged to shift from the Southern and Central
Plains to the Gulf and eastern Conus. As this occurs, the pattern
becoming less amplified and more zonal across the Conus. Further
west, a shortwave trough is expected to progress from the Four
Corners region to northern Mexico area into parts of the Central
and Southern Plains. Also, through tonight and Tuesday, a
shortwave trough over the BC and Northwest Conus vicinity moving
around upper ridge over parts of the Pacific to the Southwest
Conus will progress east near the US/Canadian border reaching
Ontario to the upper MS Valley by early Tuesday evening. At the
surface, a ridge of high pressure initially extends from the
Carolinas to TX and also into the Southern Appalachians will
remain over that same general area through tonight, but will
weaken a bit. This high start to depart to the east and southeast
on Tuesday with south to southwest return flow commencing in the
lower levels, with more westerly flow nearer to 850 mb and above.
Moisture will initially increase the most in the low levels as
Tuesday progresses especially nearer to 850 mb per 12Z HREF and
operational guidance. Meanwhile, the sfc system associated with
the trough near the US/Canadian border will progress north of the
US/Canadian border, reaching Ontario by Tuesday evening. A sfc
cold front is expected to extend to the Central Plains at that
time, with a secondary boundary sagging toward ND and the upper
MS Valley.

For Tuesday night, the shortwave that should reach Ontario to the
Upper MS Valley on Tuesday evening should move further east in
Ontario the Central Great Lakes, while the more southern shortwave
treks to eastern TX to MX. Also in the westerly/zonal flow, guidance
has a weak shortwave moving east from the Central Conus into the
OH Valley Commonwealth. Meanwhile, the sfc low near the US/Canadian
border should reach the Lake Huron vicinity with the trailing
front into the mid MS Valley to OK. In advance of the approaching
shortwave and cold front approaching from the west/northwest,
moisture will increase a bit further per 12Z HREF and operational
models, remaining most substantial nearer to 850 mb and at high
levels. An increase in clouds between about 700 mb and the 850 mb
or 875 mb should be the most notable sensible weather Tuesday.
Dry air below 850 mb or 875 mb level should preclude until after
dawn on Wednesday.

Temperatures will remain below normal tonight and Tuesday, but
will begin a trend toward normal. The sfc high to the southeast
of the area should support at least a modest ridge/valley split in
the deeper eastern valleys/hollows. Those locations should
decouple by sunset and given 3 PM EST dewpoints this afternoon
from near 10F to the mid teens, the deeper eastern valleys/hollows
should reach into the teens, with low to mid teens probable. A
north to south temperature gradient should exist again on Tuesday,
with upper 30s or around 40 highs north to upper 40s south. The
increasing low cloud cover should result in more uniform lows
generally in the low to mid 30s for Tuesday night.

.LONG TERM...(Wednesday through Monday)
Issued at 140 PM EST MON DEC 15 2025

The long-term period opens Wednesday morning with a southern
stream shortwave trough ejecting east from the Lower/Mid
Mississippi Valley as a stronger trough traverses Ontario and the
Great Lakes. A potent trough is coming ashore in the Pacific
Northwest/British Columbia. At the surface, a deep ~980mb low
will be found east of James Bay with a trailing cold front
extending southwest across the Great Lakes and back into the Lower
Missouri Valley. A much weaker surface wave is found over the Red
River Valley of the South with a cold front extending back into
Southwest Texas.

The progressive weather pattern will continue through the
extended period. Across eastern Kentucky, modest warm air
advection can be expected on Wednesday under a warm conveyor belt
jet feeding into the deep low over eastern Canada. The southern
stream disturbance is likely to generate cloud cover and possibly
an isolated light shower/sprinkle for a few spots, but most
locations should stay dry. Meanwhile, the aforementioned cold
front will stall north of the Ohio River. Overall, this will keep
Wednesday a quiet, relatively cloudy day with temperatures near
seasonable norms. The 500 hPa trough initially over the Pacific
Northwest will traverse the Rockies on Wednesday and then dive
southeast, becoming a high-amplitude trough over the Mid-Mississippi
Valley by 00z Friday, then pivoting and becoming negatively
tilted as it propagates toward New England through 00z Saturday.
This will support a strong low pressure system tracking along the
US/Canada border through that time. Ahead of the system`s
trailing cold front, a low-level theta-e analysis would suggest
two distinct warm fronts developing in the warm sector: the first
as a result of the aforementioned cold front lifting back north,
and the second lifting out of the Deep South and over eastern
Kentucky on Thursday. A notable surge of Gulf moisture is noted
with the second boundary, sending PWATs rising to near 1 inch or
better (or nearing/exceeding the 90th percentile relative to
climatology). A soaking rain is likely with the boundary; LREF
probabilities for at least 0.25 inch of precipitation range from
80 to 90 percent.

Once the cold front sweeps through late Thursday night, the air
mass dries out quickly, though deeper moisture may linger long
just long enough for just a few flakes. Heights rebound on Friday
as a seasonably strong area of high pressure settles across the
Ohio Valley. That high pressure`s tenure will be short-lived,
however, as yet another, albeit less amplified, 500 hPa trough
ejects east from the Rockies, supporting a weaker low passing
north of the US-Canada border over the weekend. This will drop
another cold front near or just south of the Ohio River on Sunday.
Low-amplitude 500 hPa ridging builds across the Central CONUS
early next week, leading to rising heights and the cold front`s
retreat back to the north.

Sensibly speaking, the temperature roller coaster will continue,
remaining one of the most notable aspects of the forecast period.
Look for a variably cloudy Wednesday with high temperatures
ranging from the mid 40s to near 50. Clouds increase again
Wednesday night, while low temperatures remain mild with lows in
the 30s. Shower chances ramp up quickly on Thursday, and it will
be much milder with highs well into the 50s (perhaps nearing 60 in
the warmest valleys). Cooler and drier weather returns for
Thursday night through Saturday morning with lows in the 20s and
highs in the 30s to near 40. The roller coaster continues heading
into the weekend, with temperatures likely surging briefly above
normal on Saturday before settling downward the second half of
the weekend, only to start rising again early next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 627 PM EST MON DEC 15 2025

VFR conditions are expected through the period with primarily just
high clouds passing from time to time. Models have trended
towards a west-southwesterly low-level jet briefly developing in
the next few hours into the overnight, and thus have introduced
LLWS to the TAFs, between 00 and 03z, peaking between 03 and 06z,
and then gradually diminishing between 06z and 09z tonight
Tuesday.

Surface winds are expected to remain light and variable, but
southwest winds

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...CMC
SHORT TERM...JP
LONG TERM...GEERTSON
AVIATION...CMC