JKL issues Area Forecast Discussion (AFD) at Oct 9, 1:45 AM EDT549
FXUS63 KJKL 090545 AAA
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
145 AM EDT Fri Oct 9 2026
.KEY MESSAGES...
- Generally dry weather with mild days and cool nights holds
through late tonight.
- Breezy and rainy conditions expected this weekend as a strong
system, including the remnants of Hurricane Isaias (currently
in the Gulf), moves northeast across the region.
- There is still considerable uncertainty with this system and
potential impacts, and forecasts will become better refined as
the event nears.
&&
.UPDATE...
Issued at 130 AM EDT FRI OCT 9 2026
No significant changes were made to the forecast with mainly just
the inclusion of the latest obs and trends for the T/Td/Sky grids.
These minor adjustments have been sent to the NDFD and web servers
along with a freshening of the SAFs and zones.
UPDATE Issued at 750 PM EDT THU OCT 8 2026
Valleys have decoupled over the past hour or so as ridge of sfc
high pressure is in place from the Upper MS Valley into the Lower
OH Valley and portions of the Appalachians. High clouds well in
advance of Isaias have spread into portions of VA and TN. These
high clouds still are on track to spread north into the southeastern
two thirds of the area tonight though this should have little
affect on radiational cooling. At this time, only minor adjustments
were made to temperatures based on recent observation trends.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 350 PM EDT THU OCT 8 2026
A pleasant early October afternoon is underway across eastern
Kentucky with bright sun buoying temperatures into the upper 70s
and lower 80s at most locations. Meanwhile, dewpoints have
dropped off markedly behind a weak cold front with readings in the
mid 30s to mid 40s (yielding ~20 to 30 percent RH values) across
all but far southeasternmost reaches of the area. That
aforementioned cold front is now to our south and east, draped
from the tip of the Delmarva to over the Tennessee Valley. Behind
that boundary, a seasonably dry surface high pressure is building
southeast from Minnesota. Glancing aloft, upper level maps show
troughing prevails over the Northeast CONUS/Eastern Canada while
ridging stands firm over much of the Western CONUS. Satellite
imagery shows Hurricane Isaias slowly drifting over the central
portions of the Gulf of America while upper level moisture venting
out of the storm is streaming to the northeast in the form of
high clouds across the Southeast US and off the Carolinas amidst
a strong 300 hPa jet extending from the Gulf Coast to out over
the Western Atlantic.
The northwestern fringe of that upper-level moisture plume will
ever so slowly drift further north overnight and filter the
moonlight over southeastern Kentucky by late tonight. But that
cloud cover should be of little hindrance to rapid radiational
cooling as the surface high slides southeast and crests over the
Central Appalachians. Light to calm winds and the dry air mass in
tandem with efficient longwave radiation loss will set the stage
for a sharp ridge-valley temperature split tonight with 10 degrees
or more of difference possible. At least patchy fog is probable
in the deeper sheltered river valleys as well. Looking ahead to
Friday, the high clouds will continue to shift a little further
north through the day as Isaias approaches the Central Gulf Coast.
This cloud cover should still be thin enough for strong solar
heating, yielding temperatures similar to if not a few degrees
warmer than today. Dew points will remain dry as well - not too
far from 40F - so relative humidity values dropping back to
between 20 to 30 percent are once again likely. Clouds continue to
thicken Friday night as Isaias makes landfall, likely near
Mobile, Alabama/Pensacola, FL. A ridge-valley temperature split
is likely to develop once again in the evening but should not be
as sharp as the prior night due to the decreasing radiative
efficiency from the thickening cloud cover as well as an uptick in
winds just off of the surface.
In sensible terms, look for dry and mild conditions and clear
skies this afternoon to give way to a cool and starlit night with
temperatures rapidly falling off after sunset. Expect tonight's
lows to range from near 40F in the colder northeastern valleys to
the lower/mid 50s on thermal belt ridges. Fog formation is likely in
the favored river valley locales. Looking ahead to Friday, sunshine
will become increasingly filtered by high clouds, but temperatures
will once again warm to the upper 70s to lower 80s for most
locations. Clouds continue to thicken and lower Friday night;
temperatures could drop off quickly in the evening but then their
fall will slow. Look for lows ranging mostly in the 50s, though
some 40s cannot be ruled out in the coldest hollows. A stray rain
shower or sprinkle is possible near the TN border by around daybreak
on Saturday.
.LONG TERM...(Saturday through Thursday)
Issued at 430 PM EDT THU OCT 8 2026
At the start of the extended period, all eyes will shift
towards the remnants of Hurricane Isaias. Model and ensemble
guidance continue to meander west and east with the storm track as
Isaias approaches the Gulf coastline. Previous guidance has
generally continued shifting the expected path west; however,
some of the latest 12Z guidance has trended back east a bit. As
Hurricane Isaias makes landfall and starts its trek north towards
the Tennessee Valley, it will be greeted by the subtropical jet
and enter a highly sheared environment. This will help weaken the
storm as it gets closer to eastern Kentucky. This will occur as
an amplified upper-level ridge across the Eastern US, with 500 mb
heights over the Commonwealth near 584-588 dam early on Saturday,
slowly departs northeast.
Showers and a few thunderstorms will spread initially across the
area from south to north on Saturday (then southeast to northwest
at times) under downsloping easterly or southeasterly winds.
Winds should gradually increase through the afternoon, peaking
between midnight and 8 AM Sunday. These easterly gusts could
generally range from 20-30 mph away from the high terrain
bordering Tennessee and Virginia. For those high terrain areas
near the state border with Tennessee and Virginia, wind gusts of
35-45 mph are becoming more probable, with the NBM, LREF, and REFS
ensembles all showing at least a 55% chance of exposed mountain
tops near Cumberland, such as Black Mountain, seeing wind gusts
around or north of 40 mph. The peak gust timing in these areas
ranges from 8 PM Saturday through 8 AM Sunday. Looking at model
soundings near Bell, Harlan, and Letcher counties, winds aloft
were as strong as 50-55 mph just below the the top of the
inversion, with stable lower levels and conditionally unstable
layers with weaker winds further above the inversion. Mountain
waves could be a possibility, which will be something that bears
watching as higher-resolution model runs become more readily
available.
With downslope flow expected, lower sfc dew points than NBM
deterministic are probable. To account for this on both Saturday
and Sunday, forecasted dew points were lowered below the
deterministic NBM using raw model guidance. Low temperatures will
generally remain in the upper 50s to low 60s both Saturday and
Sunday nights. Previously, high temperatures Saturday were wide-
ranging as the ensembles had upper 60s to mid-80s as possibilities.
This was largely due to variability in timing for the storms
arrival to the area. A sooner arrival meant more clouds and lower
temperatures, whereas a delayed arrival led to more sunshine and
ample heating into the mid-80s. However, the latest guidance has
started to come into better agreement, narrowing the spread into
the upper 60s to low 70s. Keep in mind the above scenarios can
still drive high temperatures up or down based on when the
remnants of Isaias work in here. Latest data has trended toward a
quicker arrival and thus a cloudier start to Saturday. For this
reason, high temperatures were lowered from the upper 70s in
yesterdays forecast to the low-to-mid 70s for this package. The
low 70s are around the 75th percentile of model and ensemble
guidance.
As low-level flow turns southerly around the departing high, deep
moisture associated with Isaias will begin creeping northward.
PWATs will climb toward 1.0-1.3 inches near the Tennessee border
by Saturday morning, bringing shower and thunderstorm chances to
the area from the south. The timing of rain arrival will be
earliest along the state line with Tennessee and Virginia,
potentially starting as early as 6-8 AM Saturday. Shower and
thunderstorm chances will increase through the day Saturday,
overnight, and into Sunday. By the time the system reaches the
Tennessee Valley to Lower OH Valley on Sunday, it becomes post-
tropical and follows the upper-level westerly and southwesterly
flow east into the Mid-Atlantic region by Monday. Rain is likely
across eastern Kentucky through much of Sunday, accompanied by
isolated to scattered thunderstorm chances.
Broad southwesterly flow aloft between the Atlantic ridge and
western troughing will help channel the tropical moisture plume
from the Gulf low into the Ohio Valley. This will surge PWAT
values across the JKL CWA Sunday morning into early Sunday
afternoon, with forecasted PWATs falling within the 90th
percentile. Current guidance shows the heaviest rain falling
Saturday evening through Sunday morning. The WPC has a Day 3
Marginal Risk for Excessive Rainfall for all of eastern Kentucky
for the 8 AM Saturday through 8 AM Sunday timeframe. Currently,
much of the heavier rain should remain in the Bluegrass, including
the I-64 corridor and along/west of I-75. As the system pushes
east of the area, wrap around flow may produce lingering showers
into Monday morning across portions of eastern Kentucky near the
West Virginia and Virginia borders.
Monday through Wednesday, high pressure builds into the area in
the wake of the departing system for Monday afternoon into early
Tuesday. Clouds will decrease heading into Monday evening, with
fair conditions lasting through Tuesday. A cold front does drop
southeast into and perhaps south the Ohio Valley region around
midweek, but current guidance keeps the area dry as upper ridging
builds across the Southeast. Another system could approach the
area by the tail end of next week as models show another surface
low transiting portions of the Central Conus. Temperatures Monday
through Thursday will generally range from the 70s to low 80s
during the day, with lows in the upper 50s to low 60s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 145 AM EDT FRI OCT 9 2026
At 06Z issuance time, VFR conditions were in place across eastern
Kentucky and are still expected to persist throughout the period
at the TAF sites. With high pressure cresting over the Central
Appalachians overnight, conditions will favor fog formation in
the deeper sheltered valleys and bring MVFR to IFR or perhaps
locally lower reductions at times through 14Z. Again, the TAF
sites are not expected to be affected by these reductions. Light
and variable winds will persist through around 14Z, before winds
become easterly at less than 10 kts through the rest of the
period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...GREIF
SHORT TERM...GEERTSON
LONG TERM...GINNICK
AVIATION...JP/GREIF
Source:
JKL issues Area Forecast Discussion (AFD) at Oct 9, 1:45 AM EDT---------------
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