-- Discussion containing changed information from previous version are highlighted. --
309
FXUS63 KJKL 180802
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
402 AM EDT Sat May 18 2024

.KEY MESSAGES...

- An upper level trough advancing slowly toward us from the west
  will continue to support showers and thunderstorms into Sunday,
  with the focus shifting southeastward in our area with time.

- Upper level ridging moves into the area from the northwest
  Saturday night and Sunday bringing drying, with dry weather
  expected area wide from Sunday night through Tuesday night.

- The upper level ridge shifts to our southeast by Wednesday. A
  series of upper level waves and an approaching cold front will
  bring the potential for rain back Wednesday into Thursday.

- The upper level ridge passing over will result in warmer
  weather, with above to well above normal temperatures forecast
  Sunday through Wednesday.

&&

.SHORT TERM...
-- Changed Discussion --
(Today through Sunday)
Issued at 349 AM EDT SAT MAY 18 2024

Fog has developed and become quite dense this morning especially
from Interstate 64 north, so have issued a Dense Fog Advisory
there. Cloud cover and shower activity has made detecting fog of
Interstate 64 more difficult. It appears the presence of these
clouds and precipitation are providing just enough insolation so
far to keep widespread dense fog from developing. However, if
observations show an increasing trend of lower visibilities more
consistently below one-half mile, a Special Weather Statement or
Dense Fog Advisory could be issued.

Otherwise, a slow-moving upper trough is poised to cross the
region today with light winds aloft becoming more northerly
tonight. This northerly flow will help shunt the deeper moisture
toward the southeastern Kentucky, with decreasing moisture toward
the Bluegrass region. The result will be shower and thunderstorm
chances today favoring southeastern Kentucky where there will be
categorical (75+%) PoPs, trailing off to chance (40-54%) PoPs
along and north of Interstate 64. Drier air will slowly work south
through tonight and help to diminish precipitation from northwest
to southeast.

Fog and low ceilings this morning will give way to sun breaks and
thus destabilization by midday into the afternoon, and with little
in the way of any capping mechanism, showers and thunderstorms
should quickly develop by early afternoon and persist into the
evening. As skies begin to clear tonight, expect widespread fog
formation, with potentially dense fog in the deeper sheltered
valleys especially if there is any substantial clearing.

A much drier air mass builds into the area from the north and
northeast Sunday, but there will be modest moisture and
destabilization remaining especially over the higher terrain along
the Virginia border, which warrants at least slight chance PoPs to
low-end chance PoPs for those areas.

The high temperature forecast for today continues to trend slowly
upward into the mid to upper 70s, capped by extensive low cloud
cover in the morning and then expected shower and thunderstorm
development early to mid-afternoon. Lows tonight will fall into the
upper 50s to near 60 degrees as cooler air advects into the region,
with widespread fog formation preventing temperatures in the valleys
from falling more than about 5 degrees below the ridgetops in the
mid 50s. Despite the light northerly flow Sunday will feature a lot
more sun than in previous days, with highs thus warming into the
lower 80s.

.LONG TERM...(Sunday night through Friday)
Issued at 402 AM EDT SAT MAY 18 2024

The 18/00z model suite analysis beginning Sunday evening shows a
positively-tilted 500H ridge axis oriented southwest-to-northeast
from the Ark-La-Tex across the Ohio Valley, Eastern Great Lakes
and Northern New England. This ridge is mirrored at the surface by
high pressure ridging extending from the Canadian Maritimes down
through the Mid-Atlantic to across the Tennessee Valley/Lower
Mississippi Valley. Northwest of this ridging, an ~547 dam low
resides over Saskatchewan with a a shortwave trough tracking over
the Northern Rockies/Pacific Northwest while another weak closed
~575 dam low rotates off the Southern California Coast.

The deep layer ridging will remain firmly in place over eastern
Kentucky on Monday and Tuesday with abundant sunshine each day and
mostly clear skies each night. Fog formation is likely in the
typical valley locales late each night. Daytime temperatures will
be warm, soaring into the mid to upper 80s both afternoons while
nighttime temperatures retreat into the mid 50s to lower 60s for
most locations.

The ridging becomes suppressed southeast of the Ohio Valley by
Tuesday night as the upper level low over the Canadian Prairies, the
shortwave trough over the Northwestern US, and the weak Pacific
low all translate eastward and interact/partially
phase/consolidate into a deeper closed low over the Upper/Northern
Great Lakes by late Wednesday. This stronger low then quickly
pinwheels northeastward into northern Quebec, taking the best
forcing with it. In the process, the system is expected to bring
slight height falls to eastern Kentucky as an associated cold
front settles south of the Ohio River and stalls. Guidance
increasingly favors this boundary stalling right over eastern
Kentucky on Thursday and becoming the favored corridor for a
passing Pacific disturbance to track along on Friday. Sensibly-
speaking, the cold front will bring the renewed threat for
showers and thunderstorms beginning on Wednesday and lingering
into Thursday. Any lull in the activity Thursday night will likely
yield to another round of showery weather on Friday as that
Pacific disturbance passes. Some concern for strong to severe
storms lingers, primarily on Wednesday; however, with the better
forcing remaining to our north and the better instability to our
south, there could be a relative minima in convective intensity
over eastern Kentucky. Flooding is not currently a concern.
Temperatures will trend cooler as clouds and showers arrive. Still
expect highs into the 80s on Wednesday ahead of any showers and
thunderstorms, cooling back into the 70s to around 80 for Thursday
and Friday. Nighttime lows retreat from the 60s to right around
60.
-- End Changed Discussion --

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
ISSUED AT 221 AM EDT SAT MAY 18 2024

At 06z, an area of showers extend from KSME through KLOZ to the
south of KJKL to KSJS. Outside of this area, low cigs have
developed at most locations with patchy to areas of fog.

Expect widespread IFR/LIFR/VLIFR conditions in low cigs and fog,
sometimes dense, through 12z-14z Saturday, with slowly improving
cigs and partial clearing through 15z-18z before showers and
thunderstorms develop and linger through much of the afternoon
into early evening. Thus, after about 16z expect prevailing VFR
conditions at TAF locations but with reductions at times to MVFR
and IFR conditions in showers and thunderstorms. As activity winds
down Saturday evening into the overnight, expect low cigs and fog
to redevelop at the end of the TAF period.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 9 AM EDT this morning for KYZ044-
050>052.

&&

$$

SHORT TERM...CMC
LONG TERM...GEERTSON
AVIATION...CMC