JKL issues Area Forecast Discussion (AFD) at Aug 9, 9:21 PM EDT554
FXUS63 KJKL 100121
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
921 PM EDT Sun Aug 9 2026
.KEY MESSAGES...
- Showers and thunderstorm chances will persist through the end of
the new work week. The greatest coverage is expected from
Tuesday through Friday. Some of those storms could arrive as
organized clusters with a potential for strong wind gusts.
- Isolated to scattered instances of excessive rainfall may occur
where storms are most persistent, leading to elevated concerns
for flooding later in the week.
&&
.UPDATE...
Issued at 921 PM EDT SUN AUG 9 2026
All precip except a few showers near the VA border have died out.
Have noted where precip occurred and tried to hit the fog there a
little bit harder tonight than elsewhere.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 556 PM EDT SUN AUG 9 2026
Radar imagery shows isolated to scattered showers and
thunderstorms across eastern Kentucky, similar to yesterday,
while temperatures range from the 80s to around 90F. Dew points in
the low to mid 70s make heat indices feel solidly like the 90s in
locations not recently disturbed by convection. At the surface,
there is little in the way of identifiable features--a generally
amorphous area of high pressure is in place attached to a more
defined area of high pressure centered near Bermuda. Aloft, there
is a weak perturbation at 500 hPa. Overall, differential heating
in mountainous topography as well as remnant convective outflows
are likely the primary forcing mechanisms, with some possible weak
upper-level support. Instability is once again quite high, with
RAP mesoanalysis showing 3000 to 4000 J/kg of MUCAPE in the
presence of weak shear, and PWATs ranging from 1.5 to 1.8 inches
in tandem with DCAPE values ranging from 500 J/kg in the far
southeast to 1200 J/kg in the northwest. This combination is
supportive of strong downburst winds given a robust convective
core, especially over the northwest half to two-thirds of the JKL
CWA. Farther to our north, there is a quasi-stationary frontal
boundary draped from the West Virginia Panhandle to a weak low
pressure wave in the Chicago, IL vicinity. Looking aloft, the flow
over the Ohio Valley is nearly quasi-zonal under a very broad and
low- amplitude trough over eastern Canada and adjacent portions
of the Northeast, Great Lakes, and Upper Midwest. This
troughing/quasi- zonal flow is downstream of a low-amplitude ridge
over the western CONUS and its parent upper-level ridge over the
Four Corners region.
Through the short-term, multiple disturbances will ride around the
western CONUS ridge and track east-southeast into the Ohio Valley.
As those disturbances interact with the wavering frontal boundary
between the Ohio River and Great Lakes and the moisture- and
instability-rich environment south of the boundary, guidance
continues to support multiple MCSs taking shape and diving
southeast into the Mid-Ohio Valley. Due to the subtle nature of the
perturbations initiating the MCSs and the mesoscale environmental
modifications resulting from the evolution of each, there continues
to be significant run-to-run and model-to-model variation in
output solutions. This results in low forecaster confidence in
the spatiotemporal aspects of convection during the short-term,
though there is generally somewhat better consensus for any MCSs
that develop over the Upper Midwest to dive southeast into West
Virginia, with greatest chances of impacts in the JKL CWA across
those counties closer to the KY/WV border. The latest runs of the
HRRR/RAP support the first MCS brushing our northeastern counties
Monday morning or midday, with a potential second MCS following
Monday evening and a third MCS toward daybreak on Tuesday. A
similar trend is noted in the NAM12, though with a somewhat
different spatiotemporal footprint. Wherever each MCS tracks, it
will bring the potential for torrential rainfall, especially on
the southwest side of the MCS along the upshear flank where there
will be potential for training amidst a feed of unseasonably high
PWAT and high-instability air. Additionally, any MCS passage that
coincides with peak diurnal heating/destabilization will have
heightened potential to produce damaging straight line wind gusts
on the down shear side of the MCS. Unsurprisingly, SPC has issued
a Marginal Risk for severe weather on Monday and Monday night
across northeastern Kentucky, while WPC has maintained a Marginal
ERO for locations south of the Mountain Parkway and added a Slight
Risk ERO for north of the Parkway.
Outside of the potential for convection, sensible weather conditions
will remain typical of early to mid-August, with high temperatures in
the mid 80s to around 90F while nighttime lows dip into the mid 60s
to lower 70s. Fog is likely in the favored mainstem river valleys
each night.
.LONG TERM...(Tuesday through Sunday)
Issued at 526 PM EDT Sun Aug 9 2026
Eastern Kentucky is still poised to experience rather active weather
during the long term forecast period, although specific details
remain shrouded in mesoscale uncertainty. Confidence is increasing
that swaths of very heavy rainfall will set up across portions of
the Ohio River Valley as a significant pattern change takes place.
An amplifying ridge over the South-Central CONUS will budge up
against the forecast area on Tuesday and turn the flow aloft
northwesterly. A series of low-predictability shortwave disturbances
will ride around the periphery of that ridge and produce multiple
organized thunderstorm complexes known as MCSes (Mesoscale
Convective Systems). Seasonably warm temperatures (highs in the
mid/upper 80s and lows near 70) and a very moist airmass (dewpoints
in the 70s and PWATs between 1.7 and 1.9 inches) combine to provide
more than enough instability for strong thunderstorms. Each passing
shortwave will provide sufficient shear for these organized storm
complexes, which could modify their own environment as they evolve.
Textbook theory suggests that the SW side of each complex could be a
prime area for renewed development with subsequent rounds, and we
will also need to monitor for any residual outflow boundaries left
behind by earlier rounds. While the first rounds of activity are
progged to primarily affect NE KY and the Big Sandy Basin, the
threat should shift southwest over time. This is reflected in the
SPC and WPC outlooks.
With the afternoon forecast update, SPC added a Slight Risk of
severe weather on Tuesday for most of the JKL CWA. Damaging wind
gusts are the favored convective hazard type given the MCS/clustered
storm mode, but mesoscale boundaries could yield a localized risk
for additional hazard types. Any severe weather risk will be
accompanied by a threat for excessive rainfall, and WPC has
maintained a Slight (Level 2/4) Excessive Rainfall Outlook for NE KY
on Tuesday. These NE locales will be the areas with the potential
for antecedently wet grounds from activity during the short term
forecast period. Given the more widespread coverage of strong storms
and heavy rain on Tuesday though, the Slight ERO expands to the
entire CWA on Wednesday. Flash flooding is most likely wherever
storms engage in training and/or backbuilding behaviors. So, we will
need to monitor the output of higher-resolution forecast models for
parameter spacing that favors said behaviors.
All of this activity will culminate in the approach of a cold front
in the latter stages of the period. In general, increased late week
cloud cover should work to suppress the early week heat as time
passes. Temperatures are forecast to modulate back towards more
climatologically-appropriate values in NE KY by Thursday while
higher temperatures remain in the forecast for the Cumberland River
basin. The resultant temperature gradient is visible in the grids on
Thursday, Friday, and Saturday, which tracks given that forecast
guidance has trended towards the aforementioned boundary stalling
out in the vicinity of the area. On the south side of this boundary,
there will be additional rounds of showers and storms. The intensity
and organization of that late-period activity is highly uncertain,
but this trend towards a prolonged period of wet weather is
concerning. Stay tuned for further forecast updates, and ensure that
you have multiple reliable ways to receive watches and warnings
should they be needed.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 921 PM EDT SUN AUG 9 2026
A few showers/thunderstorms lingered in far southeast KY at the
start of the period, but will die out this evening. Outside of the
precip, VFR conditions will start the evening. Valley fog will
develop during the night and bring localized IFR or worse
conditions, and will be most prevalent where rain occurred during
the afternoon and evening. However, the fog is not forecast to
affect TAF sites. Any fog will dissipate in the morning. There is
a possibility of more showers/thunderstorms developing on Monday,
but there isn't enough confidence for anything more than a PROB30
group in TAFs, and only for TAF sites northeast of the Cumberland
Basin.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...HAL
SHORT TERM...GEERTSON
LONG TERM...MARCUS
AVIATION...HAL
Source:
JKL issues Area Forecast Discussion (AFD) at Aug 9, 9:21 PM EDT---------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!
