JKL issues Area Forecast Discussion (AFD) at Aug 5, 5:06 PM EDT949
FXUS63 KJKL 052106
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
506 PM EDT Wed Aug 5 2026
.KEY MESSAGES...
- Daily shower and thunderstorm chances continue, with the
greatest areal coverage during the afternoon and evening hours
and on Friday/Saturday.
- Slow-moving showers and storms could yield isolated instances of
flash flooding in the locations where they are most persistent.
- Near-normal temperatures (highs in the 80s and lows in the 60s)
persist through the end of the forecast period.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 320 PM EDT WED AUG 5 2026
A seasonable early August afternoon is underway across eastern Kentucky.
Radar shows showers and thunderstorms ongoing, most notably along a
corridor aligned with and west of the Pottsville Escarpment. Some
convection is also noted east of the Escarpment, but it is
generally isolated to widely scattered. Outside of that activity,
partly to mostly sunny skies are supporting temperatures in the
80s at most locations recently unaffected by convection. The
latest analysis shows that ongoing convection is associated with
lingering weak upper level low remnants rotating over the Southern
Appalachians, with a particular focus along a subtle nearly
stationary boundary/enhanced PWAT gradient northwest of the upper
low remnants--basically where most of the convection is occurring
at forecast issuance time west of the Escarpment. Within the more
moist air mass over eastern Kentucky (LREF mean PWATs 1.7 to 1.8
inches), the humid and unstable air mass is supporting MLCAPE
values of 1000 to 2000 J/kg. However, effective shear remains very
minimal at under 10 kts, supporting only classic garden-variety
single-cell pulse showers and thunderstorms for most locations.
There is no readily apparent surface feature to focus the
convection either; rather, eastern Kentucky resides on the western
periphery of a broad surface high centered near Bermuda. Glancing
further upstream, a broad upper level trough is found across the
Northern Plains to Upper Midwest, supporting a surface cold front
extending from eastern Canada southwestward across Lower Michigan
and beyond to the OK/TX Panhandles.
Through the short-term, the upper level low remnants over the
Southern Appalachian will further weaken and then be sheared away
to the northeast Thursday/Thursday night as the aforementioned
trough propagates eastward along the Northern Tier of the CONUS,
brushing the Ohio Valley in the process. The upstream cold front
will stall, stretched out from the Great Lakes to the Ozarks and
Lower Missouri Valley by Thursday morning, but will gradually
drift back north as subtle shortwave troughs embedded within the
broader troughing aloft supports a weak areas of low pressure
passing along the boundary.
Through the short-term period, most of the more organized convection
associated with those perturbations should stay north and west of
the JKL CWA. Rather, diurnally induced pop-up showers and thunderstorms
will continue CWA-wide into this evening before dissipating with
the loss of daytime heating. If convection remains persistent over
a given area, the parameter space is favorable for torrential
downpours leading to flash flooding. However, most areas should
become stabilized and see the pulse-type convection collapse/die
off before any hydro concerns are able to develop. Whatever
remnant boundary remains will slowly sink southeast tonight,
becoming more centrally draped over the heart of the JKL CWA on
Thursday afternoon and evening. This will coincide with a general
increase in moisture from the west ahead of the boundary, leading
to further frontolysis of any residual stationary front. There
will be even less upper level forcing than today, so expect lower
convective coverage that is more confined to the Coalfields south
of I-64 and east of I-75. Similar to today, seasonably juicy
PWATs, minimal storm motions, weak shear, and moderate instability
will again support slow-moving heavy rainers and the potential
for isolated instances of flash flooding.
In sensible weather terms, look for scattered to numerous showers and
thunderstorms into early evening before diminishing with the loss of
daytime heating. Mostly clear skies follow overnight, with fog
developing in many areas as temperatures dip into the mid 60s to
around 70F. For Thursday, look for more of the same, though more
numerous shower and thunderstorm activity will be confined to locations
south of I-64 and east of I-75. It will be muggy with high temperatures
in the mid 80s. On Thursday evening, skies will again become
mostly clear, setting up another night with river valley fog for
Thursday night. Lows will once again be in the mid 60s to around
70F.
.LONG TERM...(Friday through Wednesday)
Issued at 503 PM EDT Wed Aug 5 2026
The long term forecast period gets off to a wet start, with
mid/upper level troughing digging deeper into the Greater Ohio River
Valley from Friday into Saturday. Embedded shortwave disturbances
are progged to propagate through this troughing pattern and towards
the forecast area in this time frame. The presence of these impulses
will bolster the areal coverage of these days' showers and storms
beyond the typical isolated to scattered summertime pop-ups
experienced earlier in the week. While the related increase in cloud
cover should keep highs in the mid 80s, the highest precipitation
chances will still align with the diurnal heating/instability cycle.
PoPs generally fall in the numerous to widespread coverage
categories on Friday (55-75%) and Saturday (50-80%) thanks to the
better support aloft.
Most of this late week convective activity will come in the form of
generic thunderstorms, as modeled wind shear remains below the 20
knot threshold. Severe thunderstorms are unlikely, but high
temperatures in the 80s and dewpoints in the 70s will yield 1500+
J/kg of SB-CAPE in the afternoon and evening hours. Ensemble mean
soundings continue to resolve high freezing levels above 15k ft and
cloud layer winds in the 15-20kt range with saturated thermodynamic
profiles. PWATs remain in the 1.6 to 1.8 inch range in this time
frame, and all of the above suggests that these storms will be
efficient rainmakers. Given the potential for antecedent rainfall
during the short term forecast period, there could be pockets of
already-saturated soils scattered around the CWA before the better
forcing arrives this weekend. This means that the rain from Friday
and Saturday's storms could prove excessive. Isolated instances of
flash flooding will be possible in locales that experience multiple
rounds of slow-moving storms multiple days in a row. WPC has
accordingly maintained Marginal (Level 1/4) EROs for the entire JKL
CWA on both Friday and Saturday
Recent forecast guidance continues to suggest that the disturbance
responsible for Saturday's activity will be better-defined than the
previous impulse on Friday. On the backside of that second,
relatively sharper shortwave trough, the flow aloft will adopt a
more zonal orientation. That quasi-zonal flow persists into the
early states of next week and advects a drier continental airmass
into the midlevels. At the same time, a ridge will be amplifying
across the Southwestern and Central CONUS. The resultant midlevel
height rises and subsidence indicate that Eastern Kentucky will get
a break from the more widespread rain chances on Sunday, but this
comes with a cost. With less clouds in the sky, efficient diurnal
warming should allow highs to climb into the upper half of the 80s
on Sunday, Monday, and Tuesday. While PWATs (mean values between 1.4
and 1.6 inches) will be relatively lower than they were this
weekend, there will still be enough humidity for widespread apparent
temperatures in the 90s. A few heat index readings near 100 degrees
cannot be ruled out, and the atmosphere may still be able to squeeze
out a few summertime pop-up showers/storms during the afternoon and
evening hours on Sunday and Monday. Rain chances ramp back up again
on Tuesday and Wednesday, but the specifics of that precipitation
forecast remain shrouded in uncertainty. Model spread begins to
increase in the latter portions of the forecast period. It is
plausible that shortwave disturbances will propagate around the
northeastern periphery of the ridge and bring chances for more
organized storms to the forecast area. The highest late-period PoPs
are generally resolved over northern portions of the forecast area,
and this aligns with some of the available extended-range convective
guidance. Trends in that guidance will be monitored in future
forecast packages, and interested parties are accordingly encouraged
to stay tuned for updates.
&&
.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
ISSUED AT 125 PM EDT WED AUG 5 2026
At 18Z TAF issuance, a diurnal CU field was rapidly developing.
As this CU deck matures, showers and thunderstorms will become
prevalent through the remainder of the afternoon into early
evening hours. PROB30s were retained for this convective
potential starting at around 18Z and continuing through mid-
evening. Winds will generally be southwest at less than 10 kts.
However, gusty and erratic winds will be possible near any storms.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...GEERTSON
LONG TERM...MARCUS
AVIATION...GEERTSON
Source:
JKL issues Area Forecast Discussion (AFD) at Aug 5, 5:06 PM EDT---------------
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