Somerset, Kentucky 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

338
FXUS63 KJKL 180519
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1219 AM EST Sat Jan 18 2025

.KEY MESSAGES...

- Rain will move into the area late tonight and continue into
  Saturday. Precipitation will change to snow from northwest to
  southeast late Saturday afternoon and Saturday night.

- Accumulating snow is forecast from Saturday night into Sunday
  night.

- Apparent temperatures are forecast near or below zero for much
  of the area on Monday, Tuesday, and Wednesday of next week.

&&

.UPDATE...
Issued at 1111 PM EST FRI JAN 17 2025

As the 00z data rolls in, an intricate accumulating snowfall
event is becoming increasingly likely during the Saturday night to
Sunday night timeframe. After rain transitions to snow behind the
arctic front late Saturday night, a baroclinic leaf (possibly
with embedded frontogenetic banding rising through a low EPV
environment atop forcing rooted near 700mb) will pass over eastern
Kentucky Sunday morning/early afternoon with widespread light to
possibly moderate snowfall. The snow will initially be relatively
wet and dense but should quickly become light and fluffy with
rising SLRs as the column cools and surface temperatures fall
into/through the 20s. Below the synoptic/mesoscale snow generation
mechanisms aloft, northwesterly flow in the shallow surface-850
mb moist cold layer behind the arctic front will favor enhanced
upslope lifting, especially along and near
Pine/Black/Log/Cumberland Mountains.

As temperatures grow colder, the CAMs/NAM12/RAP13 are picking up
on the potential for lake-enhanced snow streamers to develop off
of Lake Michigan in an initially northerly flow before effectively
coalescing into an intensifying secondary arctic cold front
(evident in the surface-925mb frontogenesis fields) that sweeps
eastward across the CWA late Sunday afternoon and evening. Model
soundings show peak omega values becoming near ideally centered
within the dendritic growth zone amidst a steep low-level lapse
rate environment extending to -20C or possibly a bit higher. This
kind of profile is supportive of very intense snowfall rates over
a brief period of time. In fact, a quick 1 to 2+ inches of
snowfall in less than an hour is conceivable, especially where the
lake-enhanced band encounters upslope lifting near/over the
Escarpment and Pine/Black/Log/ Cumberland Mountains. If this lake-
effect snowband materializes, its eastward progress will be
rapid, thus limiting excessive snowfall amounts at a given
location.

In addition to high snowfall rates and temperatures dropping
quickly in the the 10s or colder behind the band, winds along and
behind the band will become gusty. BUFKIT mixed-layer momentum
transfer is supportive of wind gusts in the 20 to 30 mph range
which could lead to very low visibility, especially during the
passage of the possible secondary front. The HRRR depicts
visibilities as low as 0.1 mile. The quickly dropping temperatures
could cause lingering liquid water to freeze as road treatments
loose efficacy in the rapidly cooling air mass. Additionally, the
strong, gusty winds will help drift the dry, fluffy snowfall onto
roadways in open areas and over ridges. Forecaster confidence in
reaching the 4" threshold for a Winter Storm Watch over portions
of the area was too low for issuance due to mesoscale effects and
model variability in the strength of the synoptic snowfall. While
Winter Weather Advisories will almost certainly be needed, a
targeted Winter Storm Warning may also be warranted as mesoscale
evolution becomes more certain. If a Winter Storm Warning is
issued, NWS Directive prohibits the issuance of Snow Squall
Warnings in the same forecast zones through the duration of the
Winter Storm Warning.

UPDATE Issued at 828 PM EST FRI JAN 17 2025

Temperatures have dropped off sharply in the sheltered valleys
east of the Escarpment, warranting a lowering in tonight`s low
temperatures for those locations. Forecast lows now range from the
upper 20s in the coldest northeastern hollows to the lower 40s in
the vicinity of Lake Cumberland. Clouds are rapidly moving in from
the southwest and that should preclude much further radiative
cooling. Locations that have remained warmer will likely see some
wet-bulb cooling once precipitation arrives overnight.

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 511 PM EST FRI JAN 17 2025

A degrading upper level low currently near the TX/OK panhandles
is getting picked up in the flow ahead of a large scale trough
diving southeast into the CONUS with an advancing arctic air mass.
As the degrading low progresses as a shortwave trough, it will
support a modest surface low which will track eastward across the
Deep South. This low then develops further in response to the
massive upper trough which evolves. The low will help to send gulf
moisture northward ahead of the large scale trough. This results
in rain developing to our west and then progressing eastward
across the area tonight. The rain lasts into the day Saturday
ahead of the approaching arctic front.

The arctic front will pass on Saturday afternoon and remaining
precipitation will transition to snow in the late afternoon and
early evening as the atmosphere cools. The surface low turns
northeast through the Carolinas on Saturday night, while the
massive upper trough continues to deepen and approach us from the
northwest. In between, our snow likely lasts through the night,
especially in far eastern and southeastern KY, carrying into
Sunday. Accumulations of around an inch are possible Saturday
night.

.LONG TERM...(Sunday through Friday)
Issued at 511 PM EST FRI JAN 17 2025

The big stories in the extended remain the potential for
accumulating snow over the weekend, and bitterly cold temperatures
the first half of next week. We are still expecting an arctic front
to move through the region over the weekend, with a southern stream
storm system becoming more developed and moving across the lower
Tennessee Valley Sunday and Sunday night. The models do still have
some differences regarding the exact track of the southern stream
system and its track through the southeastern CONUS and mid-Atlantic
region. On a larger scale, the latest model data(GFS Ensemble, GFS,
NAM12, and ECMWF) still agree fairly well with the flow pattern
aloft. The general consensus is for a large trough of low pressure
to be moving across the eastern half of the country Sunday and
Sunday night. This feature is expected to strengthen and move slowly
through the Great Lakes and New England heading into the new work
week. As this occurs, a large ridge of Arctic high pressure will
spread southeastward into the central and eastern portions of the
CONUS. This ridge will allow for an invasion of bitterly cold air
into most of the country. This ridge will slowly spread across the
CONUS the first of the new work week, and will be centered roughly
over the Ohio and Tennessee Valley regions by Tuesday night. This
will bring a surge of extremely cold air into our neck of the woods.
This will lead to bitterly cold temperatures for our area Sunday
night through Tuesday night. The coldest days will be Monday and
Tuesday, during which highs will only reach the mid to upper teens
and low to mid 20s respectively. Low temperatures are expected to
plummet into the single digits for most locations Sunday night
through Tuesday night. A few locations along and north of I-64 may
even fall slightly below zero Tuesday night. Some of the latest
model data has produced higher QPF and snowfall amounts across
eastern Kentucky, particularly the GFS and WPC guidance. That being
said, decided to follow suit in the forecast with slightly higher
snowfall totals across our area this weekend, with generally 2 to 4
inches expected.

Temperatures should finally begin to recover a bit Wednesday and
Thursday, as a northern stream trough moves through the Great Lakes,
and winds shift to the south or southwest south of the this system.
We could see highs in the mid to upper 20s on Wednesday, and in the
mid to upper 30s Thursday and Friday, as southerly flow becomes
better established. A southern stream low pressure system is still
being forecast to move across the deep south Tuesday through
Wednesday, and could bring widespread winter weather and cold
temperatures to that region. Moisture and lift on the northern
periphery of this system could move far enough north to bring
increasing clouds and some rain and snow back to eastern Kentucky
toward the end of the week. A lot of uncertainty with that system
though, so will only take it with a grain of salt for now.

Weather hazards to watch for will be accumulating snow this weekend
and any impacts it may have, especially with regard to travel. The
second hazard we will be monitoring will be the bitterly cold
temperatures we are expecting the first few days and nights next
week and any impacts that will have. If it gets as cold as it
appears it will, anyone spending time outdoors next Monday through
Wednesday will want to dress warmly and limit their time outside.
Anyone who is out driving Saturday through Sunday will need to
exercise caution in case roads, bridges, and overpasses become
slick.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
ISSUED AT 1219 AM EST SAT JAN 18 2025

VFR conditions were present at the start of the period. Mid- to
high-level clouds are streaming in from the west and will lower
to MVFR and IFR ceilings as rain develops from west to east late
tonight. The MVFR/IFR conditions and rain at times will then
persist through the day Saturday, with IFR and lower conditions
persisting into Saturday night. The rain is expected to begin
transitioning over to snow in the I-64 corridor after sunset
Saturday, with the changeover moving southeast with time through
the remainder of the TAF period.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...GEERTSON
SHORT TERM...HAL
LONG TERM...AR
AVIATION...CMC