JKL issues Area Forecast Discussion (AFD) at Nov 11, 6:38 AM EST
608
FXUS63 KJKL 111138
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
638 AM EST Wed Nov 11 2026
.KEY MESSAGES...
- A major pattern change begins tonight, with a much colder air
mass gradually working its way into Eastern Kentucky.
- Showery weather returns this evening, then lingers through
Saturday morning as the cold air advection regime persists.
- The first snowflakes of the season could fall on Friday/Friday
night, with only minor accumulations confined to the higher
terrain locales along the Virginia state line.
- Drier and cooler weather expected next week.
&&
.SHORT TERM...(Today through Thursday)
Issued at 252 AM EST WED NOV 11 2026
A split flow pattern continues across the CONUS with an active
subtropical jet stream from the subtropical Pacific east-northeast
through the Gulf Coast and Southeast US, while an active northern
stream jet stream resides across the northern half of the CONUS. Of
particular note is a a strongly a pair of digging shortwave over the
Central Plains/CONUS and southern Saskatchewan/Manitoba. These
shortwaves will help carve out a deep upper trough over the Eastern
US downstream of a rapidly strengthening upper ridge over the Great
Basin and Northern Rockies.
The initial shortwave will push a cold front across the area this
evening and overnight, bringing a round of showers and perhaps a few
thunderstorms given there could be a few hundred J/kg of SBCAPE
remaining. The most likely timing would be from mid-evening onward
for the arrival of precipitation across our eastern Kentucky zones.
A series of shortwaves then move across the area through the
remainder of the short-term, with the primary upper-level jet
remaining south of the area. This will bring pulses of cold
advection upslope rain shower activity through the day Thursday.
With persistent low clouds and cold advection, highs will only reach
the lower 50s Thursday, and even then these highs may occur during
the early morning hours before sunrise, with daytime temperatures
possibly slowly falling through the mid and upper 40s through the
day.
Manual updates to the grids were to expand PoPs across the area,
especially with the upslope cold advection activity tonight into
Thursday which the NBM tends to underestimate the coverage.
.LONG TERM...(Thursday night through Tuesday)
Issued at 518 AM EST Wed Nov 11 2026
Confidence is high that a robust troughing pattern will be in place
over the Eastern CONUS at the beginning of the long term forecast
period. The model guidance suite collectively resolves the parent
longwave feature digging deeper into the Ohio River Valley between
Thursday night and Saturday morning, with a series of embedded
shortwave disturbances rotating through the forecast area as it does
so. These impulses will keep Eastern Kentucky's weather active in
this time frame, as the related precipitation chances will overlap
with a persistent cold air advection regime and upsloped low-level
winds. This combination should yield the first snowflakes of the
season on Friday, but widespread, meaningful winter weather impacts
are not anticipated. Rather, this system will act as an appetizer
for the upcoming winter weather season, with sensible weather
impacts largely limited to noticeably colder temperatures for the
rest of the forecast period.
When the period opens on Thursday night, rain showers will likely be
ongoing across the forecast area. Northwesterly surface flow in the
wake of the previous day's frontal passage will allow temperatures
to cool into the mid 30s overnight, but the attendant cloud coverage
will inhibit radiational cooling and mute the diurnal cooling curve.
So, the baseline deterministic NBM low temperature guidance appears
too cold, despite the near-surface CAA. This event recently entered
the temporal range of higher-resolution ensemble guidance, which
confines >20% probabilities for freezing temperatures on Friday
morning to the mountains along the Virginia state line. Minimum and
hourly temperature grids were blended towards CONS guidance to
account for this, but the colder temperatures were retained at the
mountaintops. The freezing probabilities atop Big Black Mountain are
actually above 75%, which suggests that those higher terrain locales
will be the first to experience a changeover to wintery
precipitation. Expect a cool rain to dominate elsewhere at first,
although colder air is expected to move in aloft on Friday morning.
As the additional shortwave disturbances rotate around the base of
the digging parent trough on Friday, they will provide sufficient
dynamic lift for continued precipitation chances across the Ohio
River Valley. The passage of each disturbance will be marked by
shifts towards northwesterly flow aloft and thus a deeper cold air
advection regime. Modeled critical thickness values drop below the
540 decameter threshold area-wide by dawn, when model soundings
depict subfreezing temperatures at 950mb and above. The lack of a
warm nose/melting layer in those soundings effectively (and
thankfully) rules out any sleet and freezing rain potential in this
setup, but the growing influence of the cold aloft should allow snow
to mix with the rain outside of the mountain locales on Friday
morning. The longevity of those snow chances is uncertain, as
filtered diurnal heating should keep surface temperatures above-
freezing through the daytime hours. Rain should remain the dominant
precipitation type through the afternoon hours, but temperatures
will struggle to warm much higher than the low/mid 40s amidst the
deepening CAA regime. These below-normal highs will set the stage
for temperatures to easily drop below freezing-area wide on Friday
night, when a full changeover to snow is possible in the higher
terrain locales of Southeast Kentucky. The greatest and longest-
duration PoPs on Friday and Friday night will come in places with
northwest-facing slopes. There, orographic lift will combine with
the aforementioned dynamic components and a fetch of moisture off
Lake Michigan to squeeze out the most precipitation. Accumulation
potential is limited by the lack of an antecedent cold spell, but a
dusting/trace cannot be ruled out in places along and east of the
Pottsville Escarpment. The LREF resolves a >20% chance of at least
0.01 inches of snow in the SE half of the JKL CWA through Saturday
morning, with the greatest chances for measurable snow atop Pine and
Black Mountains. There, those probabilities jump to between 50 and
70%. If the accumulation threshold is raised to an inch, chances
drop to less than 25%, with contours confined entirely to the tops
of the Mountains.
The current storm total snow grids mirror these accumulation
probabilities, with only a few tenths forecast in the higher-terrain
locales of Bell, Harlan, Letcher, and Pike Counties. A dusting
cannot be ruled out further to the northwest, and neither can an
over-performance atop Black Mountain. Pattern recognition and past
experience suggest that cloud coverage and upslope PoPs will be
slower to clear than most model guidance on Saturday, when the
forecast area will remain under the influence of the deeper CAA
regime. The performance of the latest NBM configuration in such
patterns is yet to be determined this season, but antecedent local
knowledge and collaboration with neighboring WFOs called for
retaining slight chance PoPs for longer than the baseline NBM grids.
It would not be surprising if cloud cover and some flurries stick
around into Saturday morning, and that cloud cover could limit the
amount of diurnal warming realized on Saturday afternoon. Highs may
struggle to surpass the 45 degree mark, as LREF MaxT probabilities
above 50% percent values are confined to areas west of I-75 in
central Kentucky. So, Saturday looks to be the coldest day of the
season thus far.
A drier and calmer weather pattern returns to the region by Sunday,
when the previous troughing is progged to open up and propagate east
into the NE CONUS. A broad surface high pressure system looks to
build into Kentucky early next week as a split flow pattern sets up
aloft. Hysplit back trajectories suggest that a modified polar
airmass will remain in place over the CWA early next week, with
synoptic scale subsidence keeping conditions dry and skies fair.
Expect efficient diurnal processes for Sunday and beyond, with near-
normal to just-below-normal temperatures. Ample afternoon sunshine
should yield a gradual warming trend through the 50s, but
radiational cooling will yield valley lows in the 20s each night.
Both these highs and these lows are a seasonably chilly departure
from the above-normal temperatures that our area has experienced so
far this fall. So, once again, the most tangible impacts from
Friday's system are likely to stem from the the related (and quite
potent) cold air advection regime.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
ISSUED AT 638 AM EST WED NOV 11 2026
After river valley fog burns off this morning, clear skies will
remain through this morning before high and then mid-level clouds
begin to move into the area this afternoon and this evening. A
round of showers, and possibly a thunderstorm or two, moves
through the area this evening, mainly after 03z, ahead of a
disturbance and cold front. Lowering ceilings and a transition
from southwest to westerly and then northwesterly winds is
expected over the last 6 hours of the TAF period as the front
crosses the area. Reductions to MVFR or briefly lower conditions
are probable during the last 6 hours of the period. Winds will
average 10 kts or less generally from the south to southwest
through early this evening, with winds likely trending more
westerly after 00z and then northwesterly by 12z. A few gusts of
20 kts or more cannot be completely ruled out this evening and
overnight. Though thunder is possible this evening into the
overnight, probabilities were too lower to put in any particular
TAF.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CMC
LONG TERM...MARCUS
AVIATION...CMC
Source: JKL issues Area Forecast Discussion (AFD) at Nov 11, 6:38 AM EST (https://mesonet.agron.iastate.edu/p.php?pid=202611111138-KJKL-FXUS63-AFDJKL)
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