Somerset, Kentucky 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

545
FXUS63 KJKL 211846
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
146 PM EST Sun Dec 21 2025

.KEY MESSAGES...

- High pressure will usher in a cooldown for Sunday and Sunday
  night, resulting in temperatures a few degrees below normal,
  especially on Sunday night.

- Periodic rain chances are forecast from Monday night to Saturday,
  with temperatures trending to 15 to 20 degrees above normal for
  Christmas Day and Friday.

&&

.UPDATE...
Issued at 1020 AM EST SUN DEC 21 2025

In collaboration with neighboring offices and in line with current
observations, today`s dewpoints have been bumped down. Relatively
moist air continues to linger in the river valleys this morning,
but as diurnal processes take root, expect the surface to warm
and dry. Mid to high level clouds continue to stream across the
area, but a clearing trend is anticipated as a post-frontal
surface high nudges towards the area this afternoon. Northerly to
northwesterly winds and the resultant CAA will keep temperatures
north of the Mountain Parkway in the 30s for longer this morning,
and these areas could be relegated to the lower 40s this
afternoon. Elsewhere, guidance has ticked upwards with highs, and
thermometer readings in the 50s cannot be ruled out this afternoon
as the sun peeks out.

UPDATE Issued at 655 AM EST SUN DEC 21 2025

Low to mid level clouds linger in the south and southeast behind
the cold front that crossed eastern KY overnight. In the north,
some deeper valley locations that had decoupled and dropped off
to around 30 or the lower 30s such as the Johnson County and
Quicksand KY Mesonet sites and other home weather station obs and
then warmed up as the front passed up have again decoupled. Some
of the more open terrain and valley locations in the north that
did not experience and are now north of the band of low and mid
clouds have dropped into the low to mid 30s. Cold air advection
is occurring and for some locations morning min T will occur an
hour or two after sunrise. Sky cover was also adjusted to better
match recent satellite trends. Overall, more in the way of cloud
cover is expected through midday, with decreasing clouds in the
afternoon as sfc high pressure will build into the Lower OH
Valley.

&&

.SHORT TERM...(Today through Monday)
Issued at 445 AM EST SUN DEC 21 2025

Early this morning, the pattern had a somewhat zonal flavor across
the Conus with axis of a rather broad trough extended from eastern
Canada/Quebec to the eastern Great Lakes to the Lower OH Valley to
the Lower MS Valley. Upper level ridging extended from Mexico into
parts of the southwest Conus to sections of the Rockies while an
upper level low was nearing the coast of BC with an upper level
trough south to the west of the west coast of the Conus. Multiple
shortwaves were moving from the upper trough off the west coast and
around the weak upper ridging east near the US/Canadian border with
one of these near the Manitoba and Ontario border to upper MS
Valley, and another further northwest over Manitoba and an
additional shortwave was moving across BC. Other subtle shortwaves
were crossing sections of the Rockies. At the surface, an area of
low pressure was moving across Quebec with an associated cold front
that has crossed eastern KY overnight and has entered VA extending
into the Appalachians to Gulf states to Southern Plains. Behind this
front a ridge of high pressure with two centers one near the MN and
WI border and another centered in MO extended from the Upper MS
valley to the Mid MS Valley.

Today and tonight, the upper trough axis will shift east and across
eastern KY through early this evening and extend from Quebec to the
mid Atlantic states to southern Appalachians to southeast at that
time. Meanwhile, the pattern is expected to start to amplify a bit
with the upper level ridge building into the Southern Plains/Gulf
and height rises also anticipated to the lee of the Rockies over the
High Plains/High Plains/Central Conus. Some modest cold air
advection is expected through the day in eastern KY with 850 mb
temperatures expected to fall from current values between 0C north
and nearly 4C along the TN border to between around -1C north and
east around 2C TN border by the early to mid afternoon. By evening
the sfc high is expected to become centered near the southern OH and
northeast KY vicinity. The upper trough axis will move further east
tonight to the Maritimes to east of the eastern seaboard while the
upper ridge become centered from sections of the Gulf to Southern
plains and also extends into portions of the Central Conus/Southern
to Central Plains and also southeast. A trend of rising heights is
progged over the Commonwealth. The sfc high is expected to settle
over the Central to Southern Appalachians to east seaboard and
become centered over WV late tonight.

The airmass for today will not only trend colder at 850 mb, but will
also be dry on average through the column with low and mid level
moisture departing by around dawn and only some passing high and a
few mid level clouds through the day per 00Z HREF guidance.
Temperatures near to slightly below normal is often an outcome of
850 temperatures near 0C across eastern KY during the winter months
and highs are expected to maintain and north to south gradient
similar to late afternoon 850 mb temperature pattern with highs
around 40 or the lower 50s north of the Mtn Parkway and highs
generally in the mid 40s to around 50 elsewhere. Daytime mixing and
the high building in should result in afternoon mixed dewpoints in
the teens. These fairly low dewpoints and high pressure in control
should set the stage for lows tonight a bit to several degrees below
NBM guidance with the least departures for ridges/more open terrain
areas in the southwest with the larger adjustments made to eastern
valleys/hollows areas. Despite the upward trend in Coop MOS values
for tonight compared to last night, the afternoon forecast dewpoints
similar to current upstream values in IN and IL and points northwest
suggest at least some of the hollows/deeper eastern valleys should
reach the teens.
Lows reached the teens with a less substantial high just 24 hours
ago. Thus a moderate magnitude ridge/valley split was maintained for
lows tonight.

On Monday, a trend of continued rising heights are anticipated at
500 mb with return flow between sfc high shifting to the eastern
seaboard and lower pressure in sections of the western Plains/Lee of
the Rockies. Temperatures will return to above normal but low levels
will be slower to moisten. During this time, upper level ridging
becomes centered in the Gulf and extends into parts of the southeast
to portions of the Central Conus. Shortwaves in the westerly flow
will approach late Monday. Initially high level moisture/cirrus
should increases, though as the afternoon to early evening progress,
low and mid level moisture will also increase as will cloud cover.
However, with the dry low levels chances for rain will hold off
until Monday evening and Monday night.

.LONG TERM...(Tuesday through Sunday)
Issued at 146 PM EST SUN DEC 21 2025

Model guidance continues to be in very good agreement regarding
strong ridging that takes hold over the south central CONUS through
the middle of the upcoming holiday week, while deep troughing
gradually draws closer to the West Coast. After Christmas, the
eastern Pacific trough will move onshore, with some lead short
wave energy also helping to dampen the ridge. Model guidance has
trended a bit quicker with this diminishment compared to previous
runs.

The period begins Tuesday morning with the region firmly within
a warm advection regime after a warm frontal passage the day
before. Rain chances will decrease through the day on Tuesday as
a low-level jet diminishes. Highs will be in the mid to upper
50s.

A passing cold front will renew rain chances Tuesday night, with
lows in the mid 40s north of I-64, to lower 50s within the
Cumberland Valley. Low-level warm advection will return
Wednesday, keeping at least slight chances of rain in the
forecast. Highs will rebound to the upper 50s north, to the mid
60s south. Another uptick in 850-mb moisture transport,
associated with a renewed nocturnal low-level jet, will bring
likely rain chances back into the area after dark on Christmas
Eve, with the highest chances favored closer to the Ohio River.
Lows for Christmas Eve night continue to trend milder with
successive model runs, now in the mid-50s for Santa`s passage
through the region.

On Christmas Day, temperatures peak in the mid to upper 60s,
although cloud cover still looks plentiful, which should keep
readings below 70 degrees. Similar to the previous day, rain
chances will generally diminish during the daylight hours, before
yet another 850-mb jet uptick occurs Thursday night out ahead of
the next approaching cold front. This will keep the unsettled
weather going into Friday, with small rain chances lingering into
Saturday. Temperatures will cool off a bit into Saturday, but
readings will still average well above normal by 10 to 15 degrees.


&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
ISSUED AT 1250 PM EST SUN DEC 21 2025

VFR conditions continue to prevail across the region this
afternoon. Scattered (northern terminals) to broken (southern
terminals) high clouds persist, but diurnal mixing processes have
cleared low-level ceiling across all terminals. Northerly wind
components are noted in this afternoon`s observations, but these
winds are light (generally less than 6 knots). The occasional
mixing gust to 10 knots cannot be ruled out, but winds are
forecast to become light and variable overnight in response to a
building surface high. The presence of the high will foster a
clearing trend overnight into tomorrow morning, and VFR
conditions will remain in place through the end of the 18z TAF
period. Beyond then, a strengthening low level jet will yield
increasing winds and increasing cloud cover late tomorrow
afternoon.

&&

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

&&

$$

UPDATE...MARCUS
SHORT TERM...JP
LONG TERM...JKL/CMC
AVIATION...MARCUS