JKL issues Area Forecast Discussion (AFD) at Oct 8, 2:31 PM EDT321
FXUS63 KJKL 081831
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
231 PM EDT Thu Oct 8 2026
.KEY MESSAGES...
- Dry weather with mild days and cool nights holds through the end
of the work week.
- Breezy and rainy conditions are possible this weekend as a
strong system, including the remnants of Tropical Storm 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.
&&
.SHORT TERM...(Today through Friday)
Issued at 300 AM EDT THU OCT 8 2026
A broad upper trough with attendant jet streak remains situated
from the Upper Midwest through the Northeast CONUS, with its base
moving across the Great Lakes and northern Ohio Valley and into
the Mid-Atlantic today, with a second jet stream digging through
these same areas tonight and Friday. However, as the trough base
moves off the coast of New England, a narrow west-east upper ridge
will build over the TN Valley and southern Ohio Valley Friday.
A weak cold front will bring light northerly winds today under
clear skies, with near-surface flow trending more east to
southeasterly tonight. Ridge-valley splits should be rather
pronounced tonight, especially from the Kentucky River Basin
northeast, where the best radiational cooling conditions will
occur. Have thus undercut MOS guidance in these areas tonight by
several degrees, with lower 40s in the coldest locations. A little
better mixing with strengthening easterly winds may keep the
Cumberland Basin a bit more warmer.
Highs will trend about 2 to 3 degrees warmer for Friday than
today's highs, with upper 70s to lower 80s, as upper ridging moves
over the area and light southeast winds develop across the area.
.LONG TERM...(Friday night through Wednesday)
Issued at 250 AM EDT THU OCT 8 2026
The long term period will open with broad mid-level troughing
over the northeastern CONUS and ridging off the Atlantic Coast;
this subtropical ridge will expand westward during the day on
Friday, keeping weather quiet, although with high temperatures
running above average (ranging from the upper 70s to mid 80s). To
the south of the forecast area, however, Hurricane Isaias will
continue to progress northward towards the Gulf Coast, with this
system being our primary focus this weekend. The current NHC
forecast suggests that the storm will make landfall as a hurricane
in this region overnight. In a strongly sheared environment,
Isaias should be rather asymmetric, with the most impactful
weather on the eastern side of the storm. Then, the storm will
quickly weaken as it becomes post-tropical.
By Saturday, what remains of Isaias will ride north, owing to
deep southerly flow along the periphery of the ridge. This track
will set the remnant low on a collision course with a weaker cut
off low initially near the TX/LA border. Although this system will
have lost its tropical characteristics by this point, its
associated surface low should still remain well defined, with a
large precipitation shield primarily on the eastern side of the
storm. Increasingly southerly flow aloft should work to increase
PWs throughout the day, with LREF mean PW values rising to the
1.2-1.3 inch range by Saturday evening (roughly 70th to 80th
percentile compared to climatology). LREF guidance indicates that
the most likely time of rain onset would be late Saturday into
very early Sunday morning, with the earliest rain chances near the
TN line. However, there is still uncertainty regarding the exact
track and timing of the original system, and it is worth noting
that even the 25th percentile LREF suggests rain could easily
begin as early as Saturday evening. Then, the system looks to take
an eastward turn as it is pushed out by a trough arriving from
the west, with rain chances finally diminishing gradually Monday
morning.
A primary hazard with this system will be rainfall, potentially
heavy at times. WPC has introduced a Marginal Risk (Level 1/4) for
Excessive Rainfall near the I-75 corridor from Saturday morning
through Sunday morning, corresponding with the highest confidence
in higher rainfall totals.
A second hazard will be the potential for gusty winds. Saturday
evening and overnight, southeasterly winds could become breezy to
gusty, with strong winds aloft associated with Isaias impacting
the higher terrain along the TN, VA, and WV borders. Both the GFS
and ECMWF indicate 50-60 kt winds at 850 mb. 01Z NBM ensemble
guidance indicates a 30-75% probability of surface wind gusts
meeting or exceeding 40 mph overnight Saturday into Sunday.
Ensemble probabilities have increased over the last several model
runs in both the NBM and LREF ensembles. This trend will continue
to be closely monitored in subsequent model runs.
Consequently, low level shear will be quite dramatic, with even
LREF mean 0-1 km SRH in the range of 300-400 m2/s2 as the
disturbance arrives. Individual deterministic model soundings
display even higher parameters; however, any tornado risk would
depend on the timing of the lows arrival and the structure of the
system itself, particularly with respect to the nature and
location of any dry air entrainment within the parent low. Thus,
this remains a very low confidence scenario at present. A
significant mitigating factor will be the cross-barrier mid- and
low-level flow upstream and any drying/stabilizing effects from
downsloping off of the Cumberland Mountains. Global models
typically underestimate this effect at these lead times, with
high-resolution CAMS likely providing a better handle on any
mitigating impacts on this risk.
The system exits east from the area Sunday night into Monday, but
upslope west to southwesterly low-level flow and stronger
northwesterly flow aloft will mean a continued Q-G warm advection
scenario persists into the daytime hours, and thus forcing for
ascent and sufficient remaining moisture should be able to produce
some light rain lingering into Monday, at least toward the
Cumberland Mountains.
After a brief drying/clearing trend later Monday into early
Tuesday, a cold front will drop southeast through the Ohio Valley
and bring the next low chance for rain, mainly east of Interstate
75. High pressure then brings mild weather for Wednesday along
with cool nights Tuesday and Wednesday nights.
$$
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 231 PM EDT THU OCT 8 2026
At the 18z TAF issuance, VFR conditions were in place across
eastern Kentucky and are expected to persist through the period at
the TAF sites. With high pressure cresting over the Central
Appalachians tonight, conditions will favor fog formation in the
deeper sheltered valleys late tonight and early Friday morning.
Otherwise, winds will be northerly around 10 kts or less this
afternoon, becoming light and variable after sunset.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...CMC
LONG TERM...CMC/FAGAN
AVIATION...GEERTSON
Source:
JKL issues Area Forecast Discussion (AFD) at Oct 8, 2:31 PM EDT---------------
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