494
FXUS63 KJKL 301330
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
930 AM EDT Thu Jul 30 2026

.KEY MESSAGES...

- Drier weather with modestly lower humidity will prevail through
  the end of the work week.

- Thunderstorms are possible at times from Saturday through
  Wednesday.

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

&&

.UPDATE...
Issued at 930 AM EDT THU JUL 30 2026

Some fog may remain, however fog continues to mix out throughout
the area. Tweaks were made to the near term forecast to include
the latest observational and model data from around the region.
T/Td grids were freshened up, and the SAF was reran to remove
wording of fog.

UPDATE Issued at 645 AM EDT THU JUL 30 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 Friday)
Issued at 410 AM EDT THU JUL 30 2026

07Z sfc analysis shows high pressure building into the Ohio
Valley and northern Kentucky. This has brought mostly clear skies
and light winds to eastern Kentucky - good conditions for
radiational cooling. As a result, we also seeing areas of valley
fog becoming locally dense this morning while a moderate ridge to
valley temperature split has set up. Accordingly, readings vary
from the upper 50s in the low sheltered spots in the north and
east with mid 60s noted at hilltop locations. Meanwhile, amid
light and variable winds, dewpoints range from the upper 50s north
to the lower 60s in the south.

The models, and their individual ensemble suites, exhibit good
agreement aloft through the short term portion of the forecast.
They all depict Kentucky holding between two main 5h features -
a large, persistent ridge now over western Texas slipping a west
with time while the broad troughing is still over the Northeast,
initially. This eastern trough will become split by the end of the
work week as the next mid level shortwave tacks more south than
southeast to the northwest of Kentucky. As this next wave
approaches 5h heights will start to lower over the JKL CWA with
more energy arriving Friday night. Given the still small spread
among the models aloft into the start 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 nocturnal
temperatures from the NBM by adding terrain details consistent
with a good setup for radiational cooling tonight.

Sensible weather features another couple days of near perfect
mid to late summer weather - once the early morning valley fog
clears out. The fresh air mass that the high is bringing Will
start to moderate on Friday allowing for temperatures closer to
normal for high and an increase in humidity. Again tonight, we
will see a moderate ridge to valley temperature split thanks to
another night of mostly clear skies and light winds - along with
the expectations of valley fog.

The main adjustments to the NBM starting point were add some
terrain based details to temperatures tonight and lower afternoon
dewpoints today on account of the drier air mass that will be in
place. PoPs were not adjusted much - with the NBM ones again in
the reasonable low single digits or zero through the 00Z Saturday.

.LONG TERM...(Friday night through Wednesday)
Issued at 435 AM EDT THU JUL 30 2026

The main change to the grids for the first part of the extended
forecast this morning was primarily to include more in the way of
PoP details and timing per the latest CAMs guidance on Saturday.
It still looks like this next system is able to take advantage of
increasing moisture pooling and a digging mid level trough
crossing into Kentucky this weekend to bring an increasing threat
for heavy rain - mainly on Saturday and Saturday night. The sfc
pattern will feature a deepening and compact low pressure system
rolling into the state on Saturday and Saturday night lifting and
concentrating the available moisture - yielding a potential for
heavy to excessive rain. Expect the quick arrival of convection
by midday Saturday to limit the instability that can build up so
that only a small threat for organized or severe storms are
anticipated despite semi-favorable wind shear working over the
CWA.

The previous long term discussion follows:

The long-term period opens Friday morning with an upper-level trough
axis extending from Atlantic Canada southward along the Atlantic
Seaboard. Meanwhile, an ~588 dam high will be in place over
Arizona and New Mexico with broad ridging extending to the north
across the Canadian Prairies. Less prominent ridging extends east
and northeast from the high to across the Mid-Mississippi Valley,
Ohio Valley, and beyond into Southwest Quebec. A sharpening and
digging upper-level shortwave trough is also sliding across the
Upper Midwest through the eastern side of the ridge. At the
surface, high pressure, centered over West Virginia, dominates the
the Central Appalachians and into adjacent regions. Meanwhile,
low pressure is consolidating from Kansas to Iowa ahead of the
shortwave trough (and will become our most significant weather
maker of the forecast period).

The surface high pressure system and associated shortwave ridging
aloft will shift east to along the Atlantic Seaboard by the end
of the day Friday while the deepening 500 hPa shortwave dives
southeast and the attendant surface low tracks across the mid-
Mississippi Valley, moving directly over the Commonwealth Saturday
night. Some of the energy within this trough will be captured by
a broader 500 hPa trough pivoting through Eastern Canada and the
Great Lakes. Guidance suggests whatever energy remains pinches off
into a closed low that then retrogrades toward the Lower Mississippi
Valley early next week and becomes entrapped under the eastward-
building 500 hPa ridging. As a result, the surface low will
occlude, sink southward, and decay on Monday. Meanwhile, a cold
front associated with the trough passing through the Northeast
will brush to our north and east.

As the low pressure system approaches, southerly flow will send PWATs
rising to 1.75+ inches (around 80th percentile relative to climo) on
Saturday, but those higher values will be short-lived overall as
drier air sinks back in from the north behind the retrograding low
and trough brushing to our north. WPC has a Marginal to Slight
Risk for Excessive Rainfall over the JKL CWA on Saturday and
Saturday night to account for the potential of locally heavy
rainfall, which is the main concern in the long-term period.
However, several days of antecedent drying as well as the overall
progressive nature of the system should help mitigate hydro
concerns. Fortunately, the instability and shear parameter space
remains weak and that should preclude any notable severe
convective weather threat.

Sensibly, look for increasing clouds on Friday and Friday night with
high temperatures in the lower to mid 80s and low temperatures in
the lower to middle 60s. Rain chances return on Saturday and peak
at categorical PoPs Saturday night and early Sunday morning.
Daily rain chances follow for Monday through Wednesday, but
convective coverage should be more sparse and modulated by the
diurnal heating cycle. Temperatures will continue to run in the
lower to middle 80s for highs each afternoon (except upper 70s for
some locations on Sunday), while nighttime lows dip into the 65
to 70 degree range for most.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 730 AM EDT THU JUL 30 2026

VFR conditions will prevail for the duration of the 12Z TAF cycle
thanks to high pressure building into the Ohio Valley and over
Kentucky. Fog development early this morning will be largely
confined to the river valleys and will only briefly affect some of
the TAF sites. Once the remaining valley fog mixes out shortly by
13Z, expect similar conditions to those of Wednesday to hold
beyond the end of the period. Winds will be light and variable
through tonight.

&&

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

&&

$$

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