-- Discussion containing changed information from previous version are highlighted. --
484
FXUS63 KJKL 271817
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
217 PM EDT Thu Jun 27 2024

.KEY MESSAGES...

- Hotter weather is expected to make a comeback on Friday and Saturday,
  with afternoon highs around 90 or in the low 90s and heat index
  values peaking around or in excess of 100F.

- A cold front will likely bring additional rain to the area from
  late Saturday into Sunday. Any storms on Saturday afternoon and
  evening could produce strong wind gusts and heavy rain.

- Another shorter-lived cooldown is anticipated for early next
  week followed by a mid week warm up.

&&

.UPDATE...
Issued at 1106 AM EDT THU JUN 27 2024

Shower activity has been resilient and over-performing
expectations this morning in our southern and southwestern
counties, with London reporting 0.05-inch in the last couple of
hours. Have thus raised PoPs slightly so that the zone and weather
radio broadcasts mention the shower possibility. Otherwise, there
are no significant changes to the forecast.

UPDATE Issued at 930 AM EDT THU JUN 27 2024

Fog has mostly burned off this morning, with skies clearing
gradually from north to south. The mid-morning update primarily
makes minor tweaks to Sky grids to result in a slightly quicker
clearing trend through this afternoon. Otherwise, observed
temperature trends were incorporated into the grids for a smooth
weather element transition over the next few hours.

&&

.SHORT TERM...
-- Changed Discussion --
(Today through Friday)
Issued at 510 AM EDT THU JUN 27 2024

Early this morning, an upper level ridge was centered over
northern Mexico into the southwestern Conus with ridging extending
into the mid MS Valley and an upper level trough downstream from
the Hudson Bay vicinity into the eastern Conus. An upper level
low is moving across portions of BC and the Pacific Northwest with
an associated trough moving into the western Conus. Meanwhile, a
shortwave trough was moving through the Southern Appalachians
southeastern Conus. At the surface, a frontal zone extended from
the Northeast to the mid Atlantic states into the Southern
Appalachians to the Southern Plains. Nearer to the sagging frontal
zone, a few showers will still occurring near the TN/VA/KY tri
state area while further north behind the front, low clouds or
fog, in some cases dense were observed.

Today and tonight, the shortwave trough over the Southern
Appalachians and into the southeastern Conus should continue to
depart to the south and east with height rises at 500 mb
anticipated across the Commonwealth in its wake. These height
rises will occur as the ridge centered initially over Northern
Mexico and the southwest Conus flattens and builds into portions
of the Southeast including the OH and TN Valleys. At the same
time, a potentially convectively driven shortwave trough should
be in place over the Plains by this evening and near the Mid and
Upper MS Valley tonight downstream of an upper level trough that
moves near the US/Canadian border to Saskatchewan and associated
trough moving across portions of the western Conus. The consensus
of guidance builds the ridge across the southeastern Conus on
Friday, but this ridge may be a dirty ridge so to speak with
eastern KY residing on the northern periphery on Friday.

Lingering moisture over the southern counties combined with the
departing shortwave trough and front to the southeast and a
secondary weak front or sfc trough dropping across eastern KY may
result in showers lingering near some of the VA and TN border
areas this morning and perhaps into early this afternoon. However,
a drier airmass will advect in from the northwest as sfc high
pressure over the Great Lakes builds into the OH Valley. This high
works east into the Northeast to mid Atlantic states tonight and
to the eastern seaboard on Friday. Return flow and the building
ridge over the southeast will lead to a return of warmer and more
moist air once again for Friday. PW that is expected to drop off
into the 0.75 inch to 1 inch range late this afternoon and this
evening as the ridging builds in should increase again later
tonight and in particular on Friday to the 1.5 to 1.8 inch range
or near the 90th percentile. Despite forecast increases in heights
at 500 mb, the increase in moisture and daytime heating should be
sufficient to break the cap across portions of the southern half
of the area as temperatures reach the upper 80s to low 90s and
dewpoints return to the mid 60s to around 70. Coverage should be
limited to isolated to scattered however.

Other than the lingering precipitation chances this morning in
the south, fog will affect several areas this morning and is
expected to be dense in some instances. This fog should dissipate
by no later than the 9 to 10 AM timeframe. A min in precipitation
chances areawide is expected from mid to late this afternoon
through Friday morning. The ridging should support a moderate
ridge valley split tonight with some of the normally colder spots
dropping off to about 59 while coalfield ridges should not fall
below the mid to upper 60s. Along with the ridge/valley split and
following the widespread rainfall on Wednesday and Wednesday
evening, fog should develop in the valleys tonight around or
shortly after midnight and then dissipate within 2 to 3 hours
after sunrise.

.LONG TERM...(Saturday through Thursday)
Issued at 217 PM EDT THU JUN 27 2024

The forecast period will begin with southerly flow ahead of an
approaching shortwave. This upper-level feature is tracking through
the Upper Great Lakes. A trough pivoting into the Upper Midwest into
the Great Lakes will push a surface low through the region as well.
Extending southwest from the low a cold front will extend from the
Great Lakes toward the Commonwealth. Locally, surface high pressure
will be in place and will advect warmer temperatures and Gulf
moisture into the region. Highs for Saturday will be climbing into
the upper-80s to low-90s with heat indices approaching the 100
degree mark. As the front approaches the region, increasing showers
and thunderstorms are possible through the day Saturday. The SPC has
placed the entire CWA under a Day 3 Marginal Risk for severe weather
as forecast soundings ahead of the boundary show decent severe
weather indices. Instability, steep lapse rates and high PWs are in
place but the main ingredient lacking is sufficient shear to produce
and maintain severe storms. Also, if there`s widespread cloud cover,
instability value will remain meager and thunderstorms will become
more limited. However, with PWs over 2.00", an efficient shower
could put down some decent rainfall. Showers and storms continue
into Saturday night through Sunday before the front passes mid-
Sunday morning through Sunday afternoon.

Height rises and surface high pressure will begin to nudge back into
the region for Sunday night. A pretty decent temperature drop is
expected for Monday as highs and dewpoints drop 10-15 degrees making
it rather comfortable going into next week. However, this is short-
lived as a forecast 594 dm dome of high pressure builds in overhead.
This will allow for temperatures to climb back into the upper-80s to
low-90s and a return of heat indices approaching 100 degrees. This
pattern will remain in place through early Wednesday before another
shortwave dives out of the Upper Midwest. The shortwave is forecast
to track easterly with a cold front diving southeast into the
Commonwealth and bring another round of showers and thunderstorms
for the end of the forecast period.
-- End Changed Discussion --

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 138 PM EDT THU JUN 27 2024

At TAF issuance, VFR conditions were occurring under clearing
conditions from earlier cloud cover, with MVFR conditions and
light rain over far southern parts of the forecast area south of
KLOZ and KSME. High pressure continues to build over the area and
is bringing drier conditions, resulting in cig bases rising to
above 040. Winds are expected to be light and variable through the
period. Valley fog with IFR or MVFR reductions is expected to
develop between 04Z and ~12z, and this could lift into or affect
a couple of the TAF sites, though confidence in this is low at
this time. The latest statistical guidance is mixed on fog
development tonight, but is most aggressive at KLOZ tonight.
However, will pass on mentioning fog for late tonight with this
TAF package pending newer (and hopefully more consistent) model
guidance.

&&

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

$$

UPDATE...CMC
SHORT TERM...JP
LONG TERM...VORST
AVIATION...CMC