240
FXUS63 KJKL 270355 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1155 PM EDT Sun May 26 2024

.KEY MESSAGES...

- One last round of severe thunderstorms are expected overnight,
  with damaging winds isolated tornadoes being the main threats.

- Locally heavy rainfall could lead to isolated flash flooding
  tonight, particularly in the Lake Cumberland region.

- Generally cooler and less humid weather will arrive over the
  next several days. Warmer and somewhat more humid weather is
  forecast to make a comeback next weekend, with our next area
  wide chance of showers and thunderstorms.

&&

.UPDATE...
Issued at 1155 PM EDT SUN MAY 26 2024

Looks like the last round of severe weather is on the way as a
large MCS continues to grow to the west with its leading edge
accelerating toward eastern Kentucky. The kinematics and fuel will
be in place to sustain the severe threat well into the night with
expectations for a QLCS squall line to blow through between 1 and
5 AM. There will continue to be a threat for tornadoes from any
discrete cells ahead of the main line while quick hitting spin-up
tornadoes will be possible along the line while damaging wind gust
spread through the CWA - perhaps weakening as they approach the
easternmost parts. For this reason, in conjunction with SPC, a
tornado watch is in effect for the entire area through 6 am. The
flood threat remains heightened for the Lake Cumberland area of
eastern Kentucky thanks also to earlier rains. A flood watch
continues there while more localized flooding remains a concern
elsewhere depending on training and cell mergers during the
overnight event. The forecast has been updated for these threats
with the PoPs, QPF, and thunder adjusted per the latest radar and
CAMs trends. Did also add in the current obs and tendencies for
the T/Td/Sky grids. These adjustments have been sent to the NDFD
and web servers along with a freshening of the zones, HWO, SAFs,
and Flood Watch.

UPDATE Issued at 745 PM EDT SUN MAY 26 2024

23Z sfc analysis shows a meso high associated with the earlier
storms and their cold pool just east of Kentucky now and this is
creating a fairly tight pressure gradient through the area as low
pressure is approaching from the west. This gradient is also
allowing a steady flow of charged air to move back into eastern
Kentucky from the southwest. This is expected to help sustain and
fuel the next round of severe weather around or just after
midnight moving in from west to east. Currently, temperatures are
running in the mid to upper 60s most places with low 70s noted
north and still rain cooled low 60s in the far east. Meanwhile,
amid those southerly winds of 10 mph - with higher gusts,
dewpoints are rebounding and climbing back into the mid and upper
60s in the southwest parts of the JKL CWA - and still coming up
from the low 60s in the northeast. Have updated the forecast to
cover the pcpn lull this evening and its resurgence leading into
the ramp up after midnight from the next round of storms per the
latest CAMs trends. Did also include the current obs and
tendencies for the T/Td/Sky grids with this update. These
adjustments have been sent to the NDFD and web servers.

&&

.SHORT TERM...(This evening through Monday night)
Issued at 629 PM EDT SUN MAY 26 2024

Our daytime round of convection is departing to the southeast,
with mainly stratiform rain and a bit of rumbling remaining in
southeast KY. However, more active wx is on the way. A strong
surface low is passing northeast over the upper Midwest, with a
cold front stretching south southwestward. Aloft, flow is brisk
with a shortwave trough approaching from the west. Although
substantive heating is finished for the day, advection of mild,
moist air northward ahead of the front will provide instability.
ML CAPE is expected to be in the 1500-2000 J/KG range late
tonight. Another MCS is expected to travel southeast through the
region late tonight and tap into the instability. The system
will emanate from the storms currently underway over MO. A linear
system is expected by the time the storms get here, which will
present wind as a primary threat. However, very favorable shear
(directional and speed) is shown in forecast soundings, and this
would also present an increased risk of embedded QLCS tornadoes.
With a Flood Watch already in place until Monday morning, wet
ground from today`s rain, and more thunderstorms on the way, will
leave it in place. However, if tonight`s storms are progressive (as
it looks like they may be) the threat will be somewhat lessened.

The system will be exiting southeast early Monday morning, taking
our severe wx threat with it. A meaningful change in surface air
mass will be gradual, and a few more showers or thunderstorms
can`t be ruled out during the day. However, instability will be
weaker and air aloft will be extremely dry. Significant convection
is not expected to regenerate. Any precip should be gone by late
Monday evening, with fair wx overnight as drier low level air
continues to make its way in.

.LONG TERM...(Tuesday through Sunday)
Issued at 657 PM EDT SUN MAY 26 2024

Upper level longwave troughing will dominate the eastern CONUS
through most of the upcoming week, providing cooler and less humid
weather. Multiple shortwave troughs will rotate through the
larger trough during this time. As one of these passes by, there
is a potential for a few showers/thunderstorms to POP up as far
southwest as the JKL forecast area on Wednesday afternoon, but the
POP remains low.

The main upper level trough is expected to shift eastward during
the weekend, and transient ridging should pass over us from west
to east while surface high pressure also departs to the east. A
return of southerly winds, warming temperatures aloft, and at
least partial sun on Saturday will bring a warm-up. By Sunday a
shortwave trough impinges on the departing ridge and could find
enough moisture returned to the area to bring showers and
thunderstorms.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
ISSUED AT 815 PM EDT SUN MAY 26 2024

Main concern during the TAF window is another period of
thunderstorms with potentially strong gusty winds overnight. High
resolution guidance is zeroing in on a two to three hour window
for another complex of storms to move in from the west between 06
and 09Z for most sites. Went with a tempo to IFR or lower and
gusts to 40 kts to cover this threat, at this point. These could
be further refined with the next issuance of the aviation
forecast. Some storms may linger in the area through the day on
Monday so did keep some VCTS and lower clouds around into the
afternoon. Most places will see clearing late Monday. Winds will
be southerly for a time this evening at around 10 kts then settle
until the storms move through with high gusts possible. Then look
for winds to become more southwesterly to west at 10 to 15 knots
with higher gusts on Monday afternoon. Tonight we will have a shot
at some LLWS from the southwest at near 40 kts.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 8 AM EDT Monday for KYZ079-083-084.

&&

$$

UPDATE...GREIF
SHORT TERM...HAL
LONG TERM...HAL
AVIATION...GREIF