493
FXUS63 KJKL 041246
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
746 AM EST Thu Dec 4 2025

.KEY MESSAGES...

- Cold, dry weather persists through the daytime hours today.

- A wintry mix is possible overnight into Friday morning, with
  light accumulations and minor travel impacts possible for
  portions of southeast KY.

- The pattern remains active through the end of the forecast
  period, although confidence remains low in each passing system`s
  precipitation type and accumulation forecast.


&&

.UPDATE...
Issued at 742 AM EST THU DEC 4 2025

Forecast is still fairly well on track this morning. Loaded in
the latest observations to make sure the near term forecast was
on track with the current conditions. This only resulted in minor
adjustments. Continuing to see a band of light snow pass just
north of the CWA. Can`t rule out that far northern Fleming and
Rowan County may see a few flurries into the next hour, but
otherwise there should be no impacts other than low clouds. A few
locations are reporting some fog and visibility restrictions,
despite NW flow and cloud cover, but given how low the CIGs are in
these locations, expect that it`s more a factor of the low clouds
and not actual fog. Either way, expect VIS to improve over the
next few hours, but for CIGS to remain low through much of the
day.


&&

.SHORT TERM...(Today through Friday)
Issued at 513 AM EST THU DEC 4 2025

Generally zonal flow is on tap for today as a strong upper level low
moves across southeast Canada and a shortwave to our west begins to
elongate, leaving much of the Commonwealth in a W to E pattern. At
the surface, a weak cold front is expected to pass through during
the first half of the day, giving way to high pressure moving in
from the west - tracking just north of the CWA. Other than a drop in
temperatures, and a boost in some mid-level moisture (resulting in
cloud cover throughout the day), this cold front should have very
little impact and overall weather should be calm and cool throughout
the day.

That is until late this afternoon, as a strong jet streak moves over
the area and brings ovc high clouds into the region under WSW flow.
This is the first precursor to what is to come. While the center of
the surface high pressure continues to shift eastward just north of
the state tonight (Thursday night), a low pressure system and
inverted trough will be brewing across the Deep South. Models are
starting to come into better agreement that this inverted trough and
resulting boundary will reach as far north as southeast Kentucky.
Uncertainty remains, however, about how quickly moisture/precip will
move into the region, how much moisture/precip there will be, and
how far north it will reach. The evening/overnight CAMs were also in
better agreement, showing pops entering as early as 1 to 2Z, and
overspreading the S and SE CWA just before 6Z, before beginning to
exit eastward and dissipating between 12 and 15Z. The problem is
that other large-scale models (carrying over into the NBM) show a
more extensive expanse into the CWA, reaching much farther north and
taking longer to exit during the day. That being said, while we
match up well with our neighbors, and the highest pops match up well
with the CAMs, there is still some room for change, which could have
some impacts when talking about the next topic...precipitation type.

There has been a lot of uncertainty in the topic of precipitation
type as well, and while the forecasts are becoming more consistent,
it`s still a very tricky situation. Our location on the northern
fringe of this system puts us in the cold sector. However, where
precipitation and clouds are in place, temperatures will be
substantially warmer than that of the northern CWA, which may see a
bit of clearing and remain dry. The latest forecast shows overnight
low temperatures ranging from 18 degrees (well below freezing) in
the north, to around 30 degrees in the far south (just below the
freezing mark). So as the precipitation starts, the entire CWA
should be below freezing at the surface. Then as we head into the
morning hours on Friday, and the system begins to exit, surface
winds will quickly turn more southerly...and so we will begin to
warm. This may have impacts. While snow and frozen ground was the
story overnight, this warming could transition snowfall to a mix of
rain and snow, or just rain. Rain on frozen ground - freezing rain.
Thankfully, even as we start to warm, most of the precipitation
should remain snow until the temperatures are several degrees above
freezing, at which point it will just be rain. But there could be
pockets of freezing rain within the rain/snow. And just a 1 to 2
degree change in temperatures during this time period could be a
drastic difference on if the roads are fine, and if there`s more
widespread freezing rain.

Again, the models seem to be more consistent in the last couple of
runs, with generally light snow, some pockets of freezing rain, and
then a transition to all rain as the system moves out in the
morning/early afternoon and temperatures rise into the upper 30s
(north) and low/mid 40s (south). This results in generally under an
inch of snow south of I-64 during the morning hours, and only
sporadic pockets of very light ice accumulation in the same region.
This forecast also lines up well with our neighboring offices.

Given the uncertainties and the limited impacts of the current
forecast, no headlines are being issued at this time. However, we
are continuing to highlight it in the HWO and Key Messages since it
could have some impacts with the Friday morning commute. Since this
is still a very fluid/dynamic set-up, will let the day shift take
one last look at the next set of model guidance to see if anything
has shifted/altered which may lead to headlines.

According to the ECWMF, the surface low driving this system should
quickly exit off the Mid-Atlantic Coast by 0Z Saturday, with a weak
area of high pressure taking hold of the state (dry conditions), and
strong WSW flow remaining in place aloft. Despite this, the latest
forecast keeps lingering low pops across eastern KY into Friday
evening/night. Expect these pops are an artifact of the NBM (pulling
in previous data and some higher moisture models) and will be
removed in future runs...as is further discussed in the extended
portion of the forecast.

.LONG TERM...(Friday night through Wednesday)
Issued at 550 AM EST Thu Dec 4 2025

Progressive, quasi-zonal flow looks to continue aloft through much
of the long term forecast period, leading to oscillating sensible
weather conditions in Eastern Kentucky. As various shortwave
disturbances approach the forecast area, expect periodic
precipitation chances and temperature swings. Models continue to
disagree on the exact positioning and magnitude of these impulses,
but to a lesser degree than what was noted at this time yesterday.
While it remains difficult to pinpoint specific details regarding
precipitation types and potential accumulations, confidence in the
timing of these systems has accordingly improved.

When the period opens on Friday evening, a surface high pressure
system will be building into the region in the wake of Friday
morning`s activity. Recent higher-resolution guidance has been
trending drier in this time frame, but the NBM keeps light
precipitation chances in the mountains of SE KY through early
Saturday morning. If these slight chance PoPs come to fruition,
surface temps should be warm enough for most precip to fall as light
rain. The greatest PoPs (albeit less than 25%) overlap with MinTs
above freezing in the southeastern half of the forecast area, with
cooler conditions towards the Bluegrass region. Lower PoPs (closer
to 15%) extend into that cooler airmass, and marginally-favorable
cold temperatures aloft mean that a few flakes cannot be entirely
ruled out. Nevertheless, these PoPs are likely an artifact of the
NBM`s time-lagged ensemble nature, and they will likely trend
downwards in future forecast packages. The majority of precipitation
on Friday will come from the activity discussed in the short term
forecast period, and drier weather is expected on Saturday.

The surface high will propagate across the forecast area on
Saturday, leading to west-southwesterly surface flow and clearing
cloud coverage. Together, this favors MaxTs moderating into the 40s
across most of the forecast area on Saturday afternoon, and highs
could climb into the upper 40s in southern KY. The drier conditions
will continue into Saturday night, perhaps with some ridge-valley
low temperature splits. Most of the area will dip into the 20s, but
MOS guidance indicates that the relatively warmer ridgetops could
stay closer to the 32 degree mark.

Clouds look to build back in early on Sunday morning ahead of a
series of shortwave impulses impacting the forecast area early next
week. The initial disturbance is associated with a mid-/upper-level
trough over Ontario and the Eastern Great Lakes, with a second
midlevel trough over the Ozarks. The first system`s surface cold
front is forecast to come to a crawl as it approaches the Ohio River
Valley, and surface cyclogenesis looks likely immediately ahead of
the second trough axis. The resultant low-pressure system`s track
remains uncertain, as does the thermal profile above the forecast
area in this time frame. PoPs increase throughout the day on Sunday
and then linger into Monday morning, but the current p-type grids
are moreso a byproduct of the typical diurnal temperature curve than
conventional warm/cold sector conceptual models. In the baseline NBM
guidance used to populate the long term forecast grids, warmer
daytime temperatures favor rain, and cooler nighttime temperatures
favor a wintery mix. Confidence is not high enough at this moment in
time to deviate from said guidance, as evident in the four degrees
of standard deviation in some of the MOS temperature guidance for
Sunday into Monday. Interests are encouraged not to read too far
into any one deterministic model run`s accumulation maps, as they
remain bouncy with this particular system. The latest run of the
LREF Grand Ensemble depicts a 40-50% chance of a tenth of an inch of
snowfall within the 24 hour period ending on Monday evening for
areas northeast of the KY-15 corridor. These probabilities quickly
drop off with higher accumulation thresholds, but we will continue
to monitor trends in the forecast guidance suite as models hopefully
move closer to a consensus in the coming days.

Drier weather returns on Monday night into Tuesday as another
surface high quickly passes through the region. However, guidance
collectively points towards a much stronger low pressure system
developing in the Plains/Upper Midwest by midweek. The track of that
system is uncertain, but it is likely to set up a tighter pressure
gradient over the region. This favors potentially gusty
southwesterly winds across the commonwealth on Tuesday and
Wednesday. Probabilistic ensemble data currently suggests that there
is a 30 to 50 percent chance of seeing wind gusts in excess of 30
miles per hour across the forecast area on Wednesday afternoon, and
the NBM is known to under-do wind speeds in similar SW flow regimes.
Interests with outdoor events planned in this time frame, and those
with outdoor holiday decorations, should pay attention to future
forecast updates, as winds of this magnitude could potentially be
impactful. The warm air advection associated with these stronger
surface winds will likely push highs back into the mid 40s on
Tuesday and then the upper 40s on Wednesday. A few spots could cross
the 50 degree mark on Wednesday afternoon, as yet another mid/upper
level disturbance approaches from the northwest. Given this warmth,
rain would be the favored p-type with the midweek system, but a
changeover to winter precipitation cannot be ruled out in the wake
of that system`s cold frontal passage.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 721 AM EST THU DEC 4 2025

A cold front is expected to push from north to south through the
TAF sites today. While the boundary should be dry, it will result
in some low clouds. If TAF sites are currently VFR, CIGS will
trend down to MVFR then eventually to IFR throughout the day.
These CIGS will remain in place through much of the day and into
the first part of the overnight. The concern then turns to the
next system moving through overnight, which will bring a
combination of snow and rain to the region. There is also a more
uncertain possibility of light freezing rain in some locations.
Ended up going PROB30 at most TAF sites in lieu of VCSH during
this time, since it will likely be statiform light snow and not
showers (or rain). Winds will generally be light and variable
throughout the period.

&&

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

&&

$$

UPDATE...JMW
SHORT TERM...JMW
LONG TERM...MARCUS
AVIATION...JMW