989
FXUS63 KJKL 250512
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
112 AM EDT Sat May 25 2024

.KEY MESSAGES...

- Showers and thunderstorms are expected from time to time through
  the middle of next week, especially during the afternoon and
  early evening hours.

- There is a potential for severe thunderstorms on Sunday and
  Sunday night, with damaging winds and large hail being the
  primary threats.

&&

.UPDATE...
Issued at 112 AM EDT SAT MAY 25 2024

Opted to freshen up grids some to better deal with the showers
and thunderstorms moving across the area this hour. The CAMs have
not been much help on this cluster of convection so far this
evening, but seems like the 4Z HRRR is trying to latch on.
Outside that mainly just blending in the latest obs and trends.

UPDATE Issued at 1145 PM EDT FRI MAY 24 2024

A cluster of storms are firing up in the Cumberland Valley with
some growth potential per the still cooling cloud tops on IR
satellite. Accordingly, have updated the forecast to beef up the
PoPs for these considering the sat/radar and CAMs trends. Did
also include the latest 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 and SAFs.

UPDATE Issued at 745 PM EDT FRI MAY 24 2024

23Z sfc analysis shows weak high pressure over eastern Kentucky
this evening amid plenty of mid level clouds and a few instances
of convection scattered around the area. Most places have stayed
dry today and that should be the case for much of the night, but a
low chance of showers or storms will remain in the forecast
through Saturday morning. Currently, temperatures are generally
in the low to mid 70s while dewpoints remain elevated in the mid
and upper 60s - amid light and variable winds. Have updated the
forecast mainly to fine tune the PoPs through the night per the
latest ideas from the CAMs and radar trends. Did also tweak the
valley fog anticipated tonight as well as adding in the current
obs and trends for the T/Td/Sky grids. These minor adjustments
have been sent to the NDFD and web servers.

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 414 PM EDT FRI MAY 24 2024

A very quiet day continues as of late afternoon, with very dry air
and light winds aloft as weak mid-upper level ridging passes over
from west to east. A weak trough aloft is approaching behind the
ridge, and a few showers and thunderstorms have popped up to our
west and southwest. Can`t rule out something developing here
tonight as the ridging departs and the dying trough moves through,
but the timing is not favorable.

On Saturday and Saturday evening, a weakening cold front will
approach from the northwest and could help a few
showers/thunderstorms develop. However, there will once again not
be much in the way of upper level support, and the POP looks
limited.

.LONG TERM...(Sunday through Friday)
Issued at 519 PM EDT FRI MAY 24 2024

The extended period will start off on Sunday at the start of the
most active section of the forecast. As of 12Z on Sunday, a
deepening shortwave will be taking shape across the Central Plains,
along with a very strong surface low pressure system. This system is
expected to track northeast throughout the day and overnight, as it
continues to strengthen, reaching the Upper Great Lakes by 6Z
Monday. A warm front associated with this system will be parked just
north of the CWA Sunday, shifting northward. This will then be
followed by the associated cold front with this system, which is
expected to move into Western KY by 0Z Monday. It will then sweep
the state, passing through eastern KY Monday morning and early
afternoon.

There are several things to note with this system. The
first is that this track through the state is actually quite a bit
slower than previous model runs, which had the bulk of the impacts
for eastern KY on Sunday afternoon and evening, instead of Sunday
evening and Monday morning. Also by Monday, the system will be well
to our north and continuing to move away from the region, so the
best lift and instability will also be shifting north away from
eastern KY. For instance, CAPE looks great on Sunday, but storms are
expected to begin here until Sunday night, at which point surface
temps lower and best instability is cut off. Then as we head into
Monday, GFS is showing CAPE values around 2000 J/Kg (not bad), but
very little llvl wind shear. In other words, expect any storms
that do occur to be pulsy without much organization to them. SPC
also backed off on the Slight Risk across eastern KY, pushing it
back westward with the morning issuance, so that only the far SW
portion of the CWA is now included in this risk. This is also
still Day 3, so the CAMs and hi-res data doesn`t even go out this
far yet, so still quite a bit of room for change at this point.

Once this system finally moves out late Monday, and precip chances
diminish, we can expect a much cooler airmass to move into place.
This will be aided by a large upper level trough overhead of much of
the eastern U.S. which is pumping in colder Canadian air. As skies
clear out Monday night, temperatures should fall into the mid and
upper 50s, some 10 degrees or so cooler than the previous night.
Daytime temperatures will also top out in the 70s instead of the
80s over the next several days.

Models do show another upper level low rotating through the
troughing pattern and across the Ohio Valley on Tuesday. This will
be accompanied by a surface low pressure system and cold front,
which should result in additional precip to areas to our north. It`s
a bit more uncertain as to how far south this precip will drop and
if JKL will be impacted during the day. The NBM went with isolated
pops during the afternoon, and given the lower confidence, didn`t
see any reason to increase or decrease this. The associated cold
front will likely pass southward through Kentucky Tuesday night,
however, all models back off on convection during this time,
especially as CAA keeps temperatures cooler (lows in the low to mid
50s).

The front should exit by early afternoon on Wednesday, which mixed
with daytime heating and mixing, could increase pops again across
the far eastern CWA for the afternoon. Again, NBM went with low end
chance pops for this time period, and given how far out we are in
the period, didn`t see enough evidence to change this.

This system will continue to exit by Wednesday night, quickly giving
way to high pressure. Meanwhile, nearly N to S flow will keep CAA
advection in place through much of the rest of the extended. As
clouds clear out overnight Monday night, can`t rule out some of
the deeper valleys actually dropping back into the upper 40s if
this pattern plays out. The following night will be even cooler,
with more widespread upper 40s to around 50 degrees. In good news,
at last the high pressure should also remain in place through the
end of the extended, with dry weather on tap.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 810 PM EDT FRI MAY 24 2024

Mainly VFR conditions are expected for the terminals through the
period. The only exceptions would be localized IFR or worse
visibilities in valley fog overnight and early Saturday - not
expected to affect any TAF sites - and a small potential for
localized sub-VFR conditions in a passing shower or storm. Winds
will be light and variable through the period.

&&

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

$$

UPDATE...DJ
SHORT TERM...HAL
LONG TERM...JMW
AVIATION...HAL/GREIF