229
FXUS63 KJKL 191720
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
120 PM EDT Wed Jun 19 2024

.KEY MESSAGES...

- Increased cloud cover today from a disturbance to the west will
  yield some subtle relief from the more intense heat this week,
  with highs today in the middle 80s to lower 90s and heat indices
  mostly in the mid 90s with a few locations in the upper 90s.

- Hot weather persists through the remainder of the week.
  Afternoon heat indices may peak around 100 at some locations. It
  will also be dry through Friday.

- The upper level high/ridge bringing our heat wave will weaken
  next weekend and allow a cold front to move into the area, with
  PoPs peaking at 40-60% by late Sunday night.

&&

.UPDATE...
Issued at 120 PM EDT WED JUN 19 2024

With much lower heat indices expected today, the hazardous
weather outlook product was updated to remove mention of
concerning heat index values.

UPDATE Issued at 1247 PM EDT WED JUN 19 2024

With widespread, thick high clouds still in place, and expected to
remain so through most of the rest of the day, temperatures around
the area have still not rebounded to previously forecast values.
With this trend expected to continue through the rest of the day,
adjusted both hourly and max temperatures for today based on
current trends. The latest forecast update will have todays highs
only reaching the mid to upper 80s around the area, as opposed to
the upper 80s and lower 90s previously forecast. With the lower
temperatures we will also see lower heat index values today, with
max values now expected to be in the upper 80s to lower 90s across
eastern Kentucky. Changes were also made to both hourly dewpoint
temperature and RH values for the rest of today per the updated
temperature trends. An updated zone forecast text product has
already been issued that includes the new temperature forecast and
removes any remaining outdated wording. The updated forecast grids
were saved, published, and sent to NDFD and remote web servers.

UPDATE Issued at 1030 AM EDT WED JUN 19 2024

Made one quick update the forecast to remove mention of morning
fog. Temperatures at many locations around eastern Kentucky have
been running below the previously forecast hourly levels, due to
persistent, widespread, and rather thick high level cloud cover
that is currently in place. Will continue to monitor this trend to
see if it persists over the next 2 to 3 threes hours. If this
temperature trend continues, will need to issue at least one more
update to hourly and daytime max temperatures to account for it.
The updated zones have been issued. The updated grids have been
saved, published, and sent to remote web server.

UPDATE Issued at 724 AM EDT WED JUN 19 2024

There are no changes to the forecast this morning. The grids have
been updated and sent to the NDFD database, but with no changes
the zone forecasts were not updated.

&&

.SHORT TERM...(Today through Thursday)
Issued at 335 AM EDT WED JUN 19 2024

Upper-level cut-off high pressure centered over the Mid-Atlantic
region reaches peak intensity this afternoon, then weakens and
splits, with the westernmost split retrograding southwest to over
the Bluegrass State Thursday. The eastern split moves to the western
Atlantic northwest of Bermuda. Between the two, an inverted trough
moves toward the Southeast US coastline by Thursday evening.

Dew points continue to trend lower as a drier air mass moves into
the area from the Carolinas, and aided by light downslope
compressional warming. However, the drying trend has not been
continuous, with some areas maintaining lower to mid 70s dew points
still in the pre-dawn hours this morning, particularly in the Upper
Kentucky River Basin.

A warm and dry pattern continues through Thursday with no
precipitation chances. A disturbance roughly aligned with the Lower
and Middle Mississippi River Valley this morning will move northeast
into the Ohio River Valley and Midwest around the upper-level high.
While no precipitation is expected, the cloud cover will provide
significant shading from the sun, especially in the western part of
the forecast area. Thus, forecast highs for today continue a
downward trend, with upper 80s in the southwest and lower 90s in the
central and northeast parts of the CWA. Note that MOS is lower than
the NBM by a few degrees west of Interstate 75, so would not be
surprised if a few locations need to be lowered further, especially
out toward Somerset.

Drier air continues to filter into the region, and will mix down to
the surface this afternoon, which should lower dew points into the
lower to mid 60s across the area. With cloud cover lessening, expect
decent radiational cooling which should support widespread lows in
the 60s, with lower 60s in the typically cooler sheltered valleys.
Fog will be typical in the usual locations within the deeper river
valleys.

Highs rebound back into the lower to mid 90s Thursday afternoon as
the high pressure heat dome moves almost directly overhead, which
should result in mostly sunny to partly cloudy skies. Some models
depict some afternoon cumulus developing on the high terrain along
the Virginia border and moving west into eastern Kentucky later in
the afternoon, but this is not expected to result in precipitation
or lower temperatures.

.LONG TERM...(Thursday night through Tuesday)
Issued at 415 AM EDT WED JUN 19 2024

The models are in very good agreement regarding the long wave
pattern through the extended portion of the forecast. Anomalously
strong ridging will dominate over the Ohio and Tennessee valleys
through the first half of the weekend, suppressing convection and
supporting highs in the low to mid 90s each day. The ridge will
then dampen a bit and become positioned over the Desert Southwest
by early next week, as inbound short wave energy from the
northern states and south central Canada eventually move through the
Great Lakes/Ohio Valley/New England regions into early next week.
This will allow for a return of rain chances as well as a brief
break in the heat across the Commonwealth.

Temperatures will generally warm through Saturday, with highs in
the mid 90s for most locations by that time. Fortunately, dew
points will mainly be in the mid to upper 60s during the hottest
weather, keeping heat indices capped at around 100 degrees. An
approaching cold front on Sunday will allow for a return in PoPs.
These will peak in the 40-60% chance range late Sunday night with
the passage of the boundary. Lingering post-frontal moisture will
continue to allow for 20-40% PoPs Monday, and then just slight
chance PoPs (20%) south of the Hal Rogers Parkway for Tuesday.
Highs will retreat to the upper 80s to around 90 on Monday, before
warming back to the lower 90s for Tuesday, as 500 mb heights
rebound from the southwest.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
ISSUED AT 120 PM EDT WED JUN 19 2024

VFR conditions are expected to prevail through the end of the TAF
period. BKN high clouds will prevail through the rest of today,
but should steadily decrease in coverage after dark, with mostly
clear skies on tap by late this evening. Winds will average
between southerly and easterly at less than 5 kts through the
period. Some fog is expected to form overnight in valleys across
the area, but chances of fog directly impacting any of the TAF
airports are low enough to not warrant mention of fog in the TAFs
at this time.


&&

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

$$

UPDATE...AR
SHORT TERM...CMC
LONG TERM...GEOGERIAN
AVIATION...AR