112
FXUS63 KJKL 100925
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
425 AM EST Fri Jan 10 2025

.KEY MESSAGES...

- An accumulating snowfall event of significance moves into the
  area today and lingers into Saturday, the heavier accumulations
  are most probable for the more southern and southwestern
  locations.

- Below normal temperatures will persist through the next week.

&&

.SHORT TERM...(Today through Saturday)
Issued at 425 AM EST FRI JAN 10 2025

08Z sfc analysis shows the last vestiges of high pressure off to
the northeast of Kentucky while low pressure is approaching from
the southwest. The high allowed for thinner and slower arriving
high clouds in the northeast part of the area resulting in some
very cold temperatures in the sheltered valleys. Specifically
readings vary from near 5 above at the Paintsville Mesonet site
to the mid 20s in the far southwest - near Lake Cumberland.
Meanwhile, amid light and variable winds, dewpoints range from the
single digits above zero in the northeast to the mid teens in the
southwest. High clouds are continuing to stream over the area from
the southwest ahead of the approaching winter storm - becoming
thicker and lowering from west to east across the JKL CWA. These
clouds will also support moderating and rising temperatures
through dawn in the east.

The models, and their individual ensemble suites, are in terrific
agreement aloft through the short term portion of the forecast.
They all depict a deep, full-latitude trough digging through
northern Mexico this morning with several cores of energy rotating
through at mid levels well to our southwest. Kentucky starts the
period with flat ridging overhead but will quickly come under the
influence of the inbound trough. Broad southwest flow ahead of
this 5h trough will bring more energy into the area by this
afternoon as heights start to fall. In conjunction with a 3h jet
core the trough will tilt into the state by evening - digging
locally into eastern Tennessee. The jet dynamics favoring enhanced
lift will stay northeast of the area and, more impactful, just to
the south through 09Z Saturday with a sinking trend. Even so,
expect the border region with Tennessee to be under the influence
of this enhancement through Saturday morning. The northern portion
of the trough will push east quicker than the central Texas
portion sending the 5h trough axis through Kentucky by morning.
This is followed by northwest flow and a stream of energy (though
weaker) passing overhead into midday Saturday before the pattern
flattens over the Ohio Valley as the core of the trough moves off
the East Coast with its orphaned energy stream sagging south
through the Gulf Coast states. The small spread among the models
aloft to supported using the NBM as the starting point for the
forecast grids, but given the dynamic nature of the weather today
and tonight the latest high resolution CAMs guidance was leaned on
for PoP and Wx details through Saturday.

Sensible weather features a quickly deteriorating weather
situation as a broad southern winter storm tracks across the
region with its center passing well south of Kentucky. This system
is only of moderate strength for this time of year and given the
baroclinicity in place - probably owing to the lagging 5h trough
core in Texas. As a result, the storm will not bring huge amounts
of snow to the area if it would have come in at 10 mbs or so
stronger. In addition, the lack of good consolidation to the sfc
low will probably allow for some mixed pcpn to sneak north of the
Tennessee border for a time Saturday morning in our easternmost
counties. Overall, though, snow will be the predominant pcpn type
through the event for the entire CWA. Looking at the CSI potential
and enhanced lift expect there to be better banding to the south
closer to the sfc low`s center - mainly affecting the Cumberland
Valley where snow totals are at the higher end throughout the
CWA. Banding should be less prominent further north from the low,
in the portion of the CWA generally northeast of the Highway 15
corridor. However, confidence is fairly high for a 3+ inch
snowfall in these parts, as well. Accordingly, the Winter Storm
Warnings were extended northeast last evening with messaging for
lesser overall totals than the rest of the area and less
variability on the higher end on account of more limited banding
opportunities through the event. The deeper moisture starts to
pull out towards dawn, Saturday, but the low DGZ and ample
moisture will keep light snow and flurries going into the
afternoon in the eastern parts of the area - up to sunset over
the higher terrain - even as the accumulations tail off. Have
maintained the WSW structure from earlier shifts with the
southwest starting at 7 am today and ending at 10 am Saturday
while the northeast parts start at 10 am today and will linger
into the early afternoon on Saturday. QPF is highest to the south
with this system but higher snow rations in the colder air to the
north will help to somewhat balance out the totals, as well.
Temperatures will be fairly steady once the snow arrives today -
generally in the mid and upper 20s - continuing in that range
through the day Saturday.

The changes to the NBM starting point consisted primarily of
adjusting the PoPs per a rolling average of the latest CAMs
guidance with some allowance for a quicker arrival of snow on the
leading edge of the main system this morning. Leaned on the colder
side of the temperature PDF today and Saturday.

.LONG TERM...(Saturday night through Thursday)
Issued at 335 AM EST FRI JAN 10 2025

The forecast period will begin with surface high pressure as upper-
level ridging and height rises move into the region. This high
pressure will linger through the day Sunday into Monday before an
upper-level disturbance and surface low move through the Ohio Valley
with a trailing cold front moving through the Commonwealth. There`s
some model discrepancy with the PoP as the the deterministic ECMWF
keeps the CWA dry with the GFS favoring snow showers for mainly the
northeastern half of the CWA. Stayed with the NBM solution which is
a compromise between the two deterministic model runs. Snow showers
will taper off Monday night as surface high pressure builds back
into the region. Little to no snow accumulations are expected with
snow showers Monday afternoon.

The surface low responsible for the snow showers on Monday will
remain parked off the eastern seaboard with northwesterly flow
remaining over the forecast area. This will keep persistent chances
of snow showers in the forecast through much of the week but models
are keying in on the potential for a quick moving clipper system to
bring increased chances of snow showers on Wednesday before moving
off to the east by early Thursday morning. High pressure returns to
the region but northwesterly flow will keep the persistent threat
(20-30%) of upslope snow showers through the remainder of the
period. Models try to bring another system to the region for the end
of the forecast period.

Aside from the persistent threat for snow showers through the
forecast period, the coldest temperatures of the season will
accompany the snow. Highs will go from the upper-30s to low-40s on
Sunday into Monday before bottoming out midweek with highs in the
mid-20s Tuesday and Wednesday before starting to warm for Thursday
into Friday. Overnight lows will follow this same pattern with
Tuesday, Wednesday and Thursday mornings seeing single digit lows.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 115 AM EST FRI JAN 10 2025

VFR conditions will prevail through 12-15Z this morning, before
deteriorating from west-southwest to east-northeast across the
forecast area through 21Z with the approach of a widespread and
significant winter storm that will bring accumulating snow to all
TAF sites. High clouds thicken/lower through the overnight as
this storm approaches. Steady snow then develops from southwest to
northeast - primarily after 15Z - driving aviation conditions
through LIFR and worse with the lower CIGs and reduced visibility
in the snow. Winds will be variable at less than 5 kts through the
period.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 10 AM this morning to 1 PM EST
Saturday for KYZ044-050>052-060-104-106-107-109-110-119-120.

Winter Storm Warning until 10 AM EST Saturday for KYZ058-059-068-
069-079-080-083>088-108-111>118.

&&

$$

SHORT TERM...GREIF
LONG TERM...VORST
AVIATION...CMC/GREIF