738
FXUS63 KJKL 311313
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
913 AM EDT Fri Jul 31 2026

.KEY MESSAGES...

- Thunderstorms are possible at times from Saturday through
  Wednesday.

- Heavy rainfall is possible on Saturday and Saturday night and
  could lead to isolated instances of flash flooding.

&&

.UPDATE...
Issued at 913 AM EDT FRI JUL 31 2026

Fog continues to mix out across river valleys this morning, with
most having already done so. Any remaining fog should shortly mix
out within the next hour. The SAF was updated to remove fog
wording, and the grids were freshened up using the latest
observational T/Td information. No significant changes were made
to the forecast.

UPDATE Issued at 740 AM EDT FRI JUL 31 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 zones.

&&

.SHORT TERM...(Today through Saturday)
Issued at 415 AM EDT FRI JUL 31 2026

07Z sfc analysis shows high pressure sitting overtop of eastern
Kentucky. This has brought another night of light winds and mostly
clear skies to the area - great conditions for radiational
cooling. As a result, we also seeing areas of valley fog again
becoming locally dense early this morning while a decent ridge to
valley temperature split has set up. Accordingly, readings vary
from the upper 50s in a few of the low sheltered spots with mid
60s noted at many hilltop locations. Meanwhile, amid light and
variable winds, dewpoints range from the upper 50s in the east to
the lower 60s elsewhere.

The models, and their individual ensemble suites, still are
exhibiting good agreement aloft through the short term portion of
the forecast. They all depict Kentucky well northeast of a large,
persistent ridge now over the Desert Southwest that slips a bit
further west with time. Meanwhile, closer to home, the troughing
over the Northeast will continue its retrograde west - eventually
reestablishing itself centered over the western Ohio Valley by
the end of the weekend. This is the result of a deepening
shortwave topping the ridge this night and sliding southeast
through the upper Midwest. This process will bring a bubble of 5h
height rises to the JKL CWA this afternoon before they start to
fall tonight along with more energy sharpening up and pushing
into Kentucky from the northwest into Saturday evening. On account
of the rather small spread aloft among the models through the
first half of the weekend, the NBM was used as the starting point
for the forecast grids with only minor adjustments needed. These
are mainly improvements to the near term temperatures from the NBM
by adding terrain details consistent with radiational cooling. In
addition, the PoPs late tonight through Saturday were enhanced
with the latest consensus CAMs guidance.

Sensible weather features one last day of dry weather as the
humidity and warmth tick up ahead of the consolidating and
approaching sfc low. The center of the low will deepen
impressively, for this time of year, over the northwestern portion
of the Ohio Valley by Saturday morning with its warm - to
occluding - front spreading into the JKL CWA by dawn. This likely
brings a band of categorical showers and a few thunderstorms to
the area early Saturday - spreading east through the day. This
system is modeled to have a distinct dry slot and a brief warm
sector that crosses eastern Kentucky around midday and during the
afternoon with an opportunity for instability to build along with
a potential for discreet cell formation. Locations west of I-75
will have the best shot at seeing these possible supercell-like
thunderstorms and has been outlined for a slight risk of severe
weather from SPC with a non-zero threat for a tornado but damaging
wind gusts will be the main issue. In addition to the severe
potential, numerous rounds of showers and a few storms will mean a
chance for excessive rainfall and localized flash flooding -
though antecedent conditions going into the event will mitigate
this concern to some extent.

The main adjustments to the NBM starting point were to add some
terrain based details to temperatures through dawn this morning.
More impactful, the PoPs were adjusted from late tonight through
Saturday evening with considerable contributions from the latest
CAMs consensus solution.

.LONG TERM...(Saturday night through Thursday)
Issued at 445 AM EDT FRI JUL 31 2026

The first part of the extended will be dealing with a seemingly
too early synoptic low slowly working east through the eastern
Ohio Valley. This will keep low clouds and some, mostly
stratiform, rain around well into the start of the new work week
- eventually taking on a diurnal pattern to the convection.

The previous long term discussion follows:

The long-term period opens 12Z Saturday with a positively-tilted
500 hPa shortwave trough digging into the Mid-Mississippi Valley
behind shortwave ridging departing east of the Appalachians. An
~1003 mb area of low pressure will be situated over southwest
Illinois just ahead of the shortwave trough. A warm front will
extend southeast from the low across Middle Tennessee and Northern
Georgia, while a cold front arcs to the south into the Missouri
Bootheel and then southwest to over Northern Texas. Further to the
north, 500 hPa troughing is focused over and adjacent to Hudson and
James Bay, supporting a second cold front draped from a surface low
over southern Baffin Island southward to the Ottawa Valley, and then
westward across the Upper Great Lakes and Dakotas. Meanwhile further
west, an ~599 dam high is situated over the Lower Colorado River
basin while a ridge axis extends northeastward across the Canadian
Prairie Provinces.

The most active weather of the long-term forecast will occur during
the first two days of the period. The aforementioned shortwave
trough will continue to amplify as it becomes more meridionally
oriented on Saturday and Saturday night while its attendant surface
low tracks over the Lower Ohio Valley. This will send the warm front
pushing into eastern Kentucky while the trailing cold front catches
up and occludes. At the same time, the northerly trough will also
amplify across the Great Lakes and capture some or much of the
vorticity energy associated with the more southerly shortwave. There
is admittedly substantial disparity from model- to-model and run-
to-run regarding how much upper-level support remains with the
closed-off low or perturbation that lingers. In any case, the much
diminished upper-level support of the surface low leaves it to
meander southward and dissipate early next week along with its
associated frontal structures as relatively subtle weakness lingers
in the heights aloft. Meanwhile, a new area of low pressure will
form near or over the Eastern Great Lakes and New England as the
northern stream trough pulls away to the east. The system`s cold
front will sag southward into the Central Appalachians through mid-
week but stagnate there. Another upper level trough and cold front
may approach the Ohio Valley around and just beyond the end of the
forecast period.

The main concern during the long-term period will be the potential
for heavy rainfall on Saturday into early Sunday as PWATs rise to
1.75 to 2.00 inches (or 90th to 95th percentile relative to climo)
in the WAA regime ahead of the surface low. WPC`s Slight Risk (2
of 4) for excessive rainfall was expanded to cover all but the
easternmost portions of Pike County. Efficient warm layer rainfall
processes combined with the potential for training convection in
a high PWAT environment are all supportive of a locally heavy
rainfall threat, possibly leading to instances of flooding. A
notable mitigating factor is the antecedent drying ongoing prior
to the event---the 3-hour FFG currently ranges from 1.75 to 2.50
inches across most of the JKL CWA and will likely improve further
with an additional 36 to 48 hours of drying. As for any severe
weather potential, shear may be sufficient for limited organization,
but overall destabilization remains highly uncertain, especially
east of I-75. If any strong to severe storms materialize, they would
most likely occur west of I-75. PWATs fall back somewhat Sunday and
Sunday night as the surface low weakens and dissipates, but the
second cold front fails to press far enough south to drop PWAT
levels below seasonal norms. Lingering moisture combined with the
remnant weakness aloft will still combine with the daily heating
cycle to keep the continued threat for primarily afternoon and
evening convection in the forecast from Monday onward.

In sensible weather terms, clouds and shower and thunderstorm
chances increase on Saturday, with coverage peaking Saturday
night followed by a secondary peak on Sunday afternoon. Some of
the showers and thunderstorms could produce torrential downpours,
especially on Saturday and Saturday night. It will be muggy both
weekend days with high temperatures mainly in the lower 80s and
lows not far from 70F. Looking ahead to the new work week,
temperatures start the week with highs near 80F on Monday before
slowly warming into the mid to upper 80s by Thursday, while
nighttime lows range from the 60s to near 70F. Scattered showers
and thunderstorms are expected each day as well, primarily during
the afternoon and evening.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
ISSUED AT 755 AM EDT FRI JUL 31 2026

VFR conditions will continue to prevail through the 12Z TAF
period for most terminals. Mostly clear skies will be the
predominant sky cover through the bulk of the day. Limited valley
fog early this morning will likely not impact any of the TAF
sites. The fog lifts and mixes out by 13Z. After that, expect VFR
conditions to continue area-wide with the small potential for a
shower or thunderstorm to impact KSME right around dawn on
Saturday. Winds will remain light, but they will likely veer
towards a more easterly and then southerly orientation by late in
the day.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...GINNICK
SHORT TERM...GREIF
LONG TERM...GEERTSON/GREIF
AVIATION...GREIF