229
FXUS63 KJKL 271902
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
302 PM EDT Mon May 27 2024

.KEY MESSAGES...

- There will still be a chance for thunderstorms today until a
  cold front has completed it track across eastern Kentucky by
  late this afternoon.

- Following today, generally cooler and less humid weather will be
  in place over the next several days. Warmer and somewhat more
  humid weather is then forecast to make a comeback for the
  upcoming weekend along with our next area-wide chance of
  showers and thunderstorms.

&&

.UPDATE...
Issued at 1256 PM EDT MON MAY 27 2024

Temps are looking on track. Made some additional minor adjustments
to afternoon PoPs (lower) based on trends in the CAMs. No other
adjustments other than to freshen up the zone wording to remove
morning references.

UPDATE Issued at 1108 AM EDT MON MAY 27 2024

Updated the forecast package this morning to reduce PoPs and to
bring grids in line with hourly observations. Rain has moved out
of the area this morning. However, the surface cold front is only
just getting into our forecast area. It will not pass through to
our east until late today. The boundary itself is hard to
distinguish other than a slight wind shift. The drier, cooler air
will not be noticeable across the area until tonight, once the
H850 trough has managed to pass through the region sometime during
the evening. Mesoanalysis shows a pool of slightly more moist and
unstable air just ahead of the surface boundary. MLCAPEs ahead of
the front will climb to between 750-1000 J/kg and there is still
some marginal effective shear in place at around 30kts. So a few
showers and thunderstorms will still be possible until the front
has passed to our east. Therefore allowed for a slight increase in
PoPs across mainly our southeastern zones for this afternoon with
stronger diurnal heating. This would seem to be supported by the
hrrr which continues to show a threat of isolated to widely
scattered activity across the area over the next few hours. Zones
and grids have been updated and issued. Will update the zones to
freshen up wording by early afternoon.

UPDATE Issued at 746 AM EDT MON MAY 27 2024

No major changes to the forecast for the morning update. Nudged
PoPs down a bit based on latest radar trends. In addition, high-
res guidance suggests less shower/storm coverage along the cold
front until we see a bit of heating later this morning. Therefore,
have shifted coverage of precipitation further east where the
frontal position coincides with solar heating and modest
destabilization.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 440 AM EDT MON MAY 27 2024

08Z sfc analysis shows low pressure moving through the Ohio
Valley with a cold front draped northwest of the area. A squall
line of strong to severe thunderstorms - along with embedded
potential brief tornadoes - has now exited the area well ahead of
the front. Lighter showers and a few embedded thunderstorms follow
the main thunderstorm line but will rain itself out over the next
couple of hours. This will mean little threat of flooding now so
the Flood Watch was also cancelled. Mostly cloudy skies with
patchy fog and generally south to southwest winds of 10 mph or so.
Temperatures and dewpoints are fairly uniform across the area
post storm - generally in the low to mid 60s.

The models, and their individual ensemble suites, are in good
agreement aloft through the short term portion of the forecast.
They all depict general troughiness through the Ohio Valley that
will be reinforced by a couple of shortwaves moving though the
region. The first of these clears out this afternoon but another
swings by to the north tonight. The small model spread supports
using the NBM as the starting point for the short term grids along
with the incorporation of the CAMs` details for PoPs and timing
mainly just through this afternoon.

Sensible weather features drying conditions as the bulk of the
rains, along with any fog and low stratus, clears out shortly
after sunrise. The front settling through the area then brings a
renewed chance for showers and storms moving northwest to
southeast through eastern Kentucky into this afternoon. Drier
weather follows tonight, though the valley fog will likely be more
prevalent along with a small ridge to valley temperature split.
Still some clouds around on Tuesday - mainly for the northeast but
a pleasant day overall with only the barest chance for a stray
shower - probably staying to the northeast of the area.

The main adjustments to the NBM starting point consisted of
adjusting the NBM PoPs to include CAMs details for the shower and
thunder chances through this afternoon. The temperatures from the
NBM were adjusted tonight to include more terrain details on
account of a decent bout of radiational cooling expected.

.LONG TERM...(Tuesday night through Sunday)
Issued at 350 AM EDT MON MAY 27 2024

The models, and their ensemble suites, are in decent agreement
aloft through Thursday before they start to separate into the
weekend. They all depict upper level longwave troughing dominating
the eastern CONUS through most of the work week before ridging
spreads in with a return to troughing late. Multiple shortwave
troughs will rotate through the initial larger trough during this
time. A lead shortwave dives into the area and passes through on
Wednesday. This is followed by a secondary one moving by the area
further east - quicker in the ECMWF suite than the GFS and also
favoring the northeast compared to the lagging GFS. This will be
the biggest difference among the models through the period but
they do get back in line later Friday. By Friday, ridging will
move back over the area with significant height rises. However,
this does not last long as another trough starts to impinge the
Ohio Valley from the Southern Plains on Saturday - potentially
rolling into eastern Kentucky on Sunday - again quickest from the
ECMWF suite. Though it was evident, the model spread was not
sufficiently large to deviate too far from the blended multi-
model solution of the NBM.

Sensible weather will feature a cool down, and less humidity,
through the middle part of the week along with some shower and
thunderstorm chances Wednesday afternoon. High pressure then
brings drying and more sunshine to close out the week and start
the weekend, though the next system returns shower and storm
chances to the area later Saturday into Sunday.

The main adjustments to the forecast was to fine tune the
overnight temps and lows for terrain distinctions Wednesday night
through Saturday morning.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 302 PM EDT MON MAY 27 2024

Expecting predominant VFR conditions through the period with CIGS
right around 030 AGL. Consequently, there will be an occasional
drop into high end MVFR conditions at TAF sites during the first
few hours of the forecast. Sustained winds will be out of the west
at 10-15 kts with occasional gusts to around 20 kts through the
first 4-6 hours of the period and should slacken with sunset,
becoming light from the west-southwest. The more sheltered valley
locations will become variable. Winds will increase again for
Tuesday afternoon, out of the west-northwest. Drier air filtering
into the area through the overnight will tend to keep fog/mist at
a minimum.

&&

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

$$

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