-- Discussion containing changed information from previous version are highlighted. --
240
FXUS63 KJKL 081920
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
320 PM EDT Sat Jun 8 2024

.KEY MESSAGES...

- As moisture increases, there is a small chance for showers into
  this evening.

- The next passing cold front will bring increasing rain chances
  to eastern Kentucky later tonight into Sunday.

- Cooler air will be reinforced across the region early next
  week, before temperatures modify back to above normal by the end
  of the period.

&&

.UPDATE...
Issued at 1248 PM EDT SAT JUN 8 2024

Hourly grid were updated based on recent observations and trends.
Pops through early evening as the weakening convection moves east
from central to eastern KY were lowered a bit to mainly just
slight chance or sprinkles as few upstream observations had
measurable precipitation. Most recent CAMS have generally weak
activity as this moves east across the area and the latest HRRR
just has mostly just a trace of QPF as this moves into eastern
KY.

UPDATE Issued at 735 AM EDT SAT JUN 8 2024

No significant changes to the forecast with 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.

&&

.SHORT TERM...
-- Changed Discussion --
(Today through Sunday)
Issued at 445 AM EDT SAT JUN 8 2024

08Z sfc analysis shows relatively high pressure holding in place
over eastern Kentucky as low pressure is approaching from the
northwest. This has been able to keep the skies mostly clear
overnight allowing for another night of good radiational cooling.
As a result, temperatures currently vary from the low 50s in the
deeper valleys to around 60 on the ridges - and in more open
areas. Meanwhile, amid light winds, dewpoints are fairly dry in
the upper 40s to lower 50s, most places. Probably due to the
drier air in place, the river valley fog has been more subdued
than last night but in evidence from the fog channel satellite
imagery.

The models, and their individual ensemble suites, are still in
good agreement aloft through the short term portion of the
forecast. They all depict fairly fast, northwest, mid level flow
running through Kentucky on account of a stretched out low height
gyre to the north of the state and a large ridge to the south
along the Gulf Coast. Within this flow, several impulses will
pass through the area during the short term portion of the
forecast. The first of these moves through early this afternoon
with a slight drop in 5h heights as it passes. The next one slips
by to the south later tonight while the northern gyre digs south
into the Ohio Valley. The descent of this latter feature
continues into Sunday evening with more energy pushing into this
part of Kentucky. The model spread is still small enough that the
NBM was used as the starting point for the short term grids along
with the incorporation of the CAMs` details for PoPs from this
afternoon through Sunday evening.

Sensible weather features high pressure retreating to the east
allowing for some moisture return and showers to arise well out
ahead of an area of low pressure stretching east from the Central
Plains. A developing front pushes into this part of the state from
the west later today and will help to generate a few showers
initially but, likely after a lull, we will see lower cloud decks
into Sunday along with a better potential for convection in the
form of thunderstorms - mainly for the just the southern 2/3rds
of the JKL CWA. This shower and thunderstorm threat continues
through the afternoon Sunday as that front settles through the
Cumberland Valley, before diminishing west to east Sunday
evening. The building cloud and convection will limit terrain
differences and valley fog potential tonight as well as cap high
temperatures both today and Sunday to slightly below normal.

The main changes to the NBM starting point again consisted of
adjusting the NBM PoPs to include CAMs details for the shower
chances starting this afternoon and running through the day
Sunday. The temperatures from the NBM were tweaked early this
morning and again, to a more limited extent, tonight in order to
represent better terrain detail.

.LONG TERM...(Monday through Saturday)
Issued at 320 PM EDT SAT JUN 8 2024

At the surface, the period starts off with high pressure nosing east
and cold front pushing toward the Gulf Coast. The mid-levels we will
see a trough extending from the Northeast into the Ohio Valley.
These features will continue to usher in a drier and slightly below
below normal temperatures for Monday. This as ensemble mean of PWAT
values from the EPS/GEFS/GEPS show us staying below 1 inch. The dry
weather and near normal temperatures hold on through mid-week with
surface high pressure remaining in place across the Ohio Valley.

After this, there is good agreement in the ensembles and
deterministic on the surface high pressure pushing east some and
we see some moisture return albeit on the lower end, with around 1
inch PWATs. We will keep the the mainly around a 15-20 percent
PoPs in the afternoon on Thursday mainly in the Cumberland Valley
and higher terrain given some uncertainty on the mid- and upper
level pattern noted in some of the ensembles and deterministic
guidance. Then there is decent agreement on a cold front dropping
across the Ohio Valley by the end of the week into the weekend.
Even so, there is disagreement on the timing and location of this
boundary and therefore leads to uncertainty on when PoP chances
will be highest and even how high to go with PoPs. For now, stuck
close to the NBM, which keeps PoPs Friday and Saturday generally
in the 20 percent range or less. This seems reasonable given the
front looks weaker, with little change in moisture. Overall not
expecting much in the way of rainfall through the period, with
combined ensemble guidance mean of the EPS/GEFS/GEPS showing
probability of less than a quarter of an inch through the period
being around 60-70 percent.
-- End Changed Discussion --

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 214 PM EDT SAT JUN 8 2024

As high pressure continues to depart to the east, mid and high
level clouds will continue to increase to begin the period.
Isolated showers or sprinkles approaching from the west will work
across the region this afternoon to early this evening with some
associated low clouds with these. A more potent disturbance and
cold front will approach the area during the last 12 hours of the
period. Some convection associated with this could affect at least
southern portions of the area at that point, with KLOZ and KSME
likely to have the highest chances of that. With However, VFR
should prevail through at least 12Z. As the front nears and some
potential convection moves across the area, a few hours of MVFR is
forecast to end the period. Light and generally variable winds
are expected through the period. There is some variability in the
guidance with the possibility of LLWS from the southwest between
06Z and 12Z at up to 40 kts, with NBM guidance having it and
Consshort leaving it out. Although VCTS was not included in more
southern locations during the last 12 hours of the period, thunder
might occur during that time as well. At this point opted to
leave LLWS out late tonight.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...JP
SHORT TERM...GREIF
LONG TERM...DJ
AVIATION...JP