-- Discussion containing changed information from previous version are highlighted. --
639
FXUS63 KJKL 240844
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
444 AM EDT Fri May 24 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, with
  damaging winds and large hail being the primary threats.

&&

.UPDATE...
-- Changed Discussion --
Issued at 218 AM EDT FRI MAY 24 2024

Quick update to increase PoPs early across the east but also to
reduce the chance of thunder as more intense convection has moved
east of our forecast area. Showers will continue to move eastward
out of the area through dawn. Not seeing a noticeable increase in
fog on web cams. However, am seeing an increase in low stratus on
the regional satellite loop in the wake of a precipitation band
that has filled in across our eastern zones. Seems as though fog
is building down for areas across the east, but is more limited
to the river valleys further west where where rainfall has ended
and skies have at least partially cleared. Consequently beefed up
the fog just a bit across the east where low stratus is
developing.

UPDATE Issued at 1155 PM EDT THU MAY 23 2024

The severe weather has cleared out as the MCS that brought it to
the region continues to weaken and dissipate. This will set the
stage for fog formation when the clouds of the system thin and
clear. Have updated the forecast to speed up the diminishment of
the showers and also to add in the current obs and trends for the
T/Td/Sky grids. These minor adjustments have been sent to the NDFD
and web servers along with a freshening of the zones and SAFs.

UPDATE Issued at 840 PM EDT THU MAY 23 2024

00Z sfc analysis shows a meso-high working through eastern
Kentucky south of a stalled frontal boundary. The latest MCS is
starting to rain itself out over the CWA this evening but a few
strong to severe storms will be possible for another hour or so
out ahead of the main storm cluster. For this reason, and in
coordination with MRX and SPC, we have extended the severe watch
until 10 pm but dropped it generally west of I-75 where conditions
have stabilized. Temperatures currently vary from the lower 60s
in the recently rain cooled areas to the low 70s in the far east.
Dewpoints remain elevated in the mid to upper 60s most places amid
mostly light winds away from any thunderstorms. Have updated the
forecast mainly to fine tune the PoPs through the rest of the
night per radar and CAMs trends. Did also include the current obs
and tendencies for the T/Td/Sky grids. Additionally, the fog was
hit hard late tonight with clearing and thinning of the mid and
high clouds anticipated. These adjustments have been sent to the
NDFD and web servers along with a freshening of the zones, SAFs,
and HWO - primarily to address the extension of the watch.
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&&

.SHORT TERM...
-- Changed Discussion --
(This evening through Friday night)
Issued at 455 PM EDT THU MAY 23 2024

A stalled, ill-defined frontal boundary is located just north of
KY late this afternoon. On the south side of the front, our air
mass is mild and fairly humid, with dew points running in the 60s.
Temperatures are running in the 70s, being held back during the
day by earlier clouds and precip. Never the less, it`s enough to
support another round of thunderstorms heading in from central KY,
helped along by a weak mid/upper level trough. Modest shear is
also present, and marginally severe storms can`t be ruled out with
the instability/shear combo, with Severe Thunderstorm Watch 293
continuing until 8 PM for our western counties.

The convection is expected to weaken as it exits east tonight.
Clouds will try to break up as mid-upper levels dry, but
radiational cooling after the precip will probably result in fog
and low clouds developing and lasting into Friday morning.

The fog and low clouds will dry up by mid day and sun/heating will
cause destabilization again. However, the currently stalled
frontal boundary will lift north away from the region as a warm
front, and the only mid/upper level wave to be seen in models
should have its main influence to our south in the afternoon and
evening. That being the case, despite instability, the probability
of rain appears to be relatively low Friday and Friday night due
to lack of support, and nothing more than a small chance (30%) has
been used.

.LONG TERM...(Saturday night through Thursday)
Issued at 444 AM EDT FRI MAY 24 2024

The extended starts off fairly active across the CONUS, with a
couple of short waves exiting our area and the southeastern CONUS to
start things off. The short wave in our vicinity will allow
scattered showers and storms to linger across our area for a bit,
before they exit the area around dawn Sunday, as the upper level
system moves off to our east. Another much more potent weather
system will be taking shape to our west over the central Plains, in
the form of a vigorous short wave. The shortwave will develop on the
southern periphery of a larger upper level system that will be
moving slowly across southern Canada to finish out the weekend. As
the short wave moves across the central Mississippi Valley and
across the Great Lakes on Sunday, it will strengthen. As this
happens, a steady fetch of warm, moist air from the Gulf of Mexico
will stream into the Tennessee and Ohio Valleys. This influx of air
will create moist and unstable conditions ahead of the approaching
short wave. A surface based area of low pressure will also form over
the Plains on Sunday, and will strengthen and move east in response
to the eastward progression of the upper level system mentioned
earlier.

What this all amounts to, is conditions will be primed for shower
and thunderstorm development across our entire area, especially
Sunday night and Monday, as the cold front moves through. The latest
model soundings indicate plenty of instability will be in place
Sunday night into Monday, with a weak low level capping inversion
also evident. There will also be fairly strong flow aloft Sunday
night and Monday, particularly at the 850 and 500 mb levels. All
these components will favor not only general shower and thunderstorm
development across the area heading into Memorial Day, but will also
provide the necessary ingredients for strong to severe storms. The
latest day 3 outlook from the Storm Prediction Center has a marginal
to slight risk of severe weather in place for our area from Sunday
morning through Monday morning, so we will need to monitor the
situation closely over the next couple of days for severe weather
potential.

The best chances for showers and storms for us will be from Sunday
afternoon through Monday, as the initial short wave moves through,
followed by the surface front. Once the cold front has moved through
Monday, the models suggest that another upper level disturbance will
break off from the back side of the eastward moving southern Canada
system and then dive southward through the Great Lakes and into the
Ohio and Tennessee Valleys Monday night and Tuesday. With some
moisture still in place, showers and storms will likely linger
around the area Tuesday night and Wednesday, before finally moving
off to our east with the departing upper low late Wednesday
afternoon. After that, a ridge of high pressure should settle over
the region to finish out the week, with decreasing clouds and dry
weather taking over the end the week.

Based on current model data trends, temperatures should be generally
above normal during the period. We will probably see slightly below
normal readings Wednesday and Thursday, after the second upper level
system moves through, but overall, daytime highs should range from
the upper 70s to mid 80s around the area, as persistent southerly
and southwesterly flow will be in place in association with the
passage of the late weekend system. As of now, it appears that the
primary forecast concern will be the potential for severe weather
Sunday through Monday, which we will keep a close eye on in the days
leading up to the event. If severe weather were to occur, the
primary threats would be damaging wind gusts and large hail, with
isolated tornadoes also possible.
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&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 218 AM EDT FRI MAY 24 2024

A band of showers has increased in coverage across our east and is
currently moving eastward. However, the threat of thunder is
waning quickly as more intense convection has moved east of our
forecast area. Not seeing a noticeable increase in fog on web
cams. However, am seeing an increase in low stratus on the
regional satellite loop in the wake of a precipitation band that
has filled in across our eastern zones. Based on observations,
fog is building down for areas in our east, but is more limited
to the river valleys further west where rainfall has ended and
skies have at least partially cleared. Consequently a mix of
aviation conditions continues to exist across the area as the
remnants of yesterday afternoon and evening`s convection continues
to dissipate. Expect flights conditions will be quite variable
through the remainder of the early morning to around sunrise. Have
trended VSBYS and CIGS downward, especially across our east with
the developing stratus and fog. Generally went with a pessimistic
start to flight conditions through dawn, IFR or worse. VFR
conditions are expected to return mid to late Friday morning.
Winds will be generally light and variable through the period -
away from any storms.

&&

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

$$

UPDATE...RAY
SHORT TERM...HAL
LONG TERM...AR
AVIATION...HAL/GREIF/RAY