-- Discussion containing changed information from previous version are highlighted. --
499
FXUS63 KJKL 210355 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1155 PM EDT Fri Sep 20 2024

.KEY MESSAGES...

- A potential for showers and thunderstorms returns late tonight
  and Saturday and then persists much of the time over the next
  week. The highest probability is around mid week.

- Daily high temperatures will approach 90 degrees through the
  weekend, then trend lower - into the 70s by Wednesday.

&&

.UPDATE...
-- Changed Discussion --
Issued at 1155 PM EDT FRI SEP 20 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 along with
a freshening of the zones and SAFs.

UPDATE Issued at 740 PM EDT FRI SEP 20 2024

23Z sfc analysis shows a weak pressure pattern still in place over
eastern Kentucky with the diurnal cycle dominating the weather
conditions. In this case, with no triggers for convection, all we
saw were cu developing during the day and these are now waning
into the evening. Skies are currently mostly clear, though some
high clouds may impinge from some convection to the northwest
deeper into the evening. Even so, still anticipate enough clear
skies for radiational cooling allowing a small ridge to valley
temperature difference to show up through the night. Currently,
temperatures vary from the lower to mid 80s on the ridges, and
over the more open terrain, to the lower and mid 70s in the more
sheltered valleys. Meanwhile, amid light winds, dewpoints remain
elevated and vary from the mid and upper 50s northeast to the mid
60s in some of the Cumberland Valley sheltered spots. Have updated
the forecast mainly to add in the latest obs and trends for the
T/Td/Sky grids. These minor adjustments have been sent to the NDFD
and web servers.
-- End Changed Discussion --

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 526 PM EDT FRI SEP 20 2024

Upper level ridge remains in place over the Tennessee and lower
Ohio Valley through the period. Weak shortwave energy will track
along the northern periphery of this ridge, just managing to skirt
northern portions of our area late tonight into Saturday morning.
At the surface, a weak surface cold front will drop southward to
the Ohio River by tomorrow morning before stalling out.

Sensible weather features a very warm short term. With H850 temps
between 19-21C afternoon high temperatures will once again climb
to near or around 90 for portions of the area Saturday. Overnight
lows will remain generally in the 60s, except for our most
sheltered valleys...where temperatures may drop into the upper 50s
in a few spots tonight and tomorrow night. The main forecast
challenge for the short term will be the potential for rain late
tonight and through the day Saturday. MOS guidance does not look
promising but operational synoptic models do show the potential
for some light precipitation across mainly northern portions of
the forecast area. CAMs look more promising and do show some
isolated to scattered convection across the area through the day.
NBM blends manage to generate some 20-30 PoPs across the area as
well. Ensemble probabilistic data indicates a 50-80% GTE to 0.01
inches of rainfall, mainly along and north of a Irvine to Jackson
to Pikeville line. Forecast soundings and CAMS also indicate
MLCAPEs climbing to between 1000-1500 J/kg across a large portion
of eastern Kentucky during the day tomorrow. Therefore was
comfortable leaning towards the higher end of model guidance for
PoPs, generally going with a 30% chance across the northern half
of our forecast area, and 20% elsewhere.

.LONG TERM...(Sunday through Friday)
Issued at 408 PM EDT FRI SEP 20 2024

The flow pattern aloft across the CONUS to begin the extended period
will feature a large and broad trough in place over the desert
southwest, with a short wave trough taking shape along the eastern
edge of the larger upper feature. another more vigorous trough is
forecast to move slowly eastward along the norther border of the US
north of the Great Lakes, then make a northward push as it
intensifies. Another area of low pressure is progged to be in place
just off the Mid-Atlantic region. The trough that will be in place
over the west-central Plains early Sunday will move slowly our way
heading into the first of the upcoming work week. A surface front
extending from this feature northward to the southern Canadian
trough will push through the Great Lakes and Ohio Valley regions
Sunday night and Monday, bringing good chances for showers and few
storms to eastern Kentucky. This initial system will move slowly but
steadily through the region, keeping chances for showers and storms
in our area through Tuesday evening.

Once the first system moves off to our east, another trough will be
right on its heels. This second system, according to the latest GFS,
ECMWF, GFS Ensembles, and WPC guidance, will move out of the south
central Plains into the western Great Lakes Tuesday night through
Friday. However, the models area also trying to produce a well
defined tropical cyclone over the Gulf of Mexico, which could move
inland late Friday, and perhaps affect the progression of the second
Plains trough. If this happens, and a TC does form in the Gulf,
we`ll need to watch it closely to see whether or not it moves close
enough to our area after becoming extra-tropical to bring another
round of rain to eastern Kentucky by the end of next week.

The extended looks to start off quite warm, with well above normal
highs in the upper 80s on tap for Sunday, as the initial trough of
low pressure approaches from the west. After that, an invasion of
extensive cloud cover and multiple rounds of rain will act to keep
temperatures quite a bit below normal for the rest of the period,
especially once the first trough moves by and winds shift to the
west and then northwest toward the middle and end of the week.
Daytime highs should top out in the 70s Wednesday, Thursday, and
Friday. Aside from lightning with general thunderstorms through out
the week, there are no weather hazards expected across eastern
Kentucky.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 800 PM EDT FRI SEP 20 2024

VFR flight conditions will likely hold through the period.
Some minor valley around fog again tonight will not affect any
terminals. Winds will be light and variable through Saturday
morning, then increase a bit from the west-southwest to around 5
kts through the day, ahead of a weak cold front that is expected
to stall north of our area, through the Ohio River Valley. Any
convection that develops will have a low probability of hitting a
TAF site so have left any TS or VCTS out of the TAFs for now -
through the highest potential would be for KSYM from late tonight
through early afternoon Saturday.

&&

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

$$

UPDATE...GREIF
SHORT TERM...RAY
LONG TERM...AR
AVIATION...RAY/GREIF