809
FXUS63 KJKL 020555
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
155 AM EDT Wed Apr 2 2025

.KEY MESSAGES...

- After briefly cooler than normal conditions Tuesday,
  temperatures return to above normal levels Wednesday into next
  weekend.

- At least northwest parts of eastern Kentucky will probably see
  another round of strong to severe storms Wednesday night, and
  then again potentially Thursday into Thursday night.

- We are looking for repeated rounds of heavy rain and
  thunderstorms to affect eastern Kentucky from Wednesday night
  through Sunday - especially northwest parts of the forecast area
  where between 3 and 6 inches of rain will be possible over those
  several days. This area remains in a flood watch from Wednesday
  evening through Sunday morning.

&&

.UPDATE...
Issued at 155 AM EDT WED APR 2 2025

Temperatures have dropped a few degrees below previously forecast
lows for most locations, but appear to be slowing their fall as
the surface pressure gradient is tightening over the region.
Anticipate temperatures, which currently range from the mid 30s in
the colder sheltered northeastern valleys to the lower 50s west
of I-75 and in southern thermal belts, to become nearly steady
soon and even slowly rise at many spots through the remainder of
the night.

UPDATE Issued at 1100 PM EDT TUE APR 1 2025

No significant changes were made to the forecast with mainly just
the inclusion of the latest 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, SAFs, and FFA.

UPDATE Issued at 730 PM EDT TUE APR 1 2025

23Z sfc analysis shows high pressure to the northeast of the state
in control of the weather over eastern Kentucky. This is working
to settle the winds and with mainly just some high clouds around.
Currently temperatures are running in the low 50s north and in the
lower 60s for the south. Meanwhile, amid light easterly winds,
dewpoints are generally in the low to mid 30s. Do anticipate a
small to moderate ridge to valley temperature split which the
forecast has well handled. For this update, have mainly just added
in the latest 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 Wednesday night)
Issued at 537 PM EDT TUE APR 1 2025

A very deep lee low is over CO late today, also being supported by
a strong upper level trough over the western CONUS. Meanwhile,
ridging at the surface and aloft is downstream over our area. A
closed upper low will develop attendant to the surface low as it
moves northeast across the plains and upper Midwest during the
period. Our ridging will depart to the east, and the large and
intense surface low will tighten our pressure gradient tonight.
This will bring a more humid and much warmer air mass into our
area on brisk south to southwest winds. These winds will blow
largely a little above the surface tonight, but will mix to the
ground on Wednesday as heating occurs. Gusts around 40 mph are
forecast for our western counties at this time. If this still
looks to be the case with new data tonight, a wind advisory may
need to be issued for our western counties for Wednesday, joining
our neighbors to the north and west. Winds will subside somewhat
going into Wednesday night as heating is lost.

Isentropic lift with the arrival of the air mass may support some
showers and thunderstorms during the day on Wednesday, mainly
around mid day in our northern counties. These would be fueled by
elevated instability and be largely garden variety. Although,
surface based instability is expected in the afternoon, forecast
soundings look capped. If something should break through the cap
late in the day, there would be some concern due to the
combination of shear and instability expected. Our better chance
at thunderstorms appears to be Wednesday night. An organized line
is expected to develop to our northwest and move southeast into
our area late, posing a severe wx risk due to impressive shear,
even through instability will wane during the night.

Won`t rule out some heavy rainfall/flooding risk due to training
cells overnight Wednesday night in our northwest counties, and
the Flood Watch beginning Wednesday night remains in place.
However, the bigger threat is further to the northwest, and this
initial rain is more likely to moisten the ground to set us up for
potential problems in the long term period.

.LONG TERM...(Thursday through Tuesday)
Issued at 520 PM EDT TUE APR 1 2025

The models, and their individual ensemble suites, continue to be
in pretty good agreement aloft through the first part of the
weekend before some differences of note start to crop up in the
handling of the Southwestern trough opening up. They all depict
that deep Southwestern trough anchoring the 5h pattern -
incredibly - all the way into the weekend while strong ridging
stays parked over the southeast portion of the country. This will
lock in an extended period of fast southwest mid-level flow
scouring moisture northeast from a wide open western Gulf of
America for a near continuous flux of moisture into the region.
Within the flow, several impulses of concern will ride past
eastern Kentucky. While one of the most significant ones of these
will be passing out of the area Thursday morning, we will see
another, weaker one, later that night before a third one pushes
through early Saturday morning. By early Sunday a substantial
portion of the Southwestern trough finally works east into the
Mid-Mississippi Valley helping to shove the blocking Southeast
ridge further away from Kentucky. This process also pulls a large
trough southward from eastern Canada sending 5h height falls
through this part of the state. With the pattern finally on the
move, a stream of energy will settle into the Ohio Valley and
press south into the JKL CWA later Monday. This energy swath will
linger overhead through early Tuesday when the large northern
trough`s axis will finally sweep east of the Ohio Valley -
stronger and more definitively in the ECMWF cluster than the GFS.
This will turn the mid-level flow more sharply to the northwest
bringing a pattern more favorable for drying.

The small model spread aloft through Saturday supported using the
NBM as the starting point for the forecast grids then more
consideration was given toward the ECMWF`s cluster solution
through the rest of the period. Did make some adjustments mainly
to add more terrain distinction to the temperatures in the
southeast parts of the area each night through Saturday.

Sensible weather features a tale of two portions of the CWA with
the northwest under the gun for periods of excessive rains and
cooler conditions while the southeast avoids much of the weather
and stays quite warm through Saturday. The first wave will leave a
stalled boundary just to the northwest of, or a bit into, the JKL
CWA and serve to focus the convection threat - though most
probably we will see a fade out of the initial stronger and
heavier convection into the morning. Then, perhaps a the boundary
helps to ignite more convection later that afternoon for more
shower and storms. Severe weather will be possible given the
position of the boundary, warmth and sfc moisture in place, and a
favorable wind field for organized convection. However, extensive
cloud cover and a worked over atmosphere without much dynamics
aloft appear to be a limiting factor on widespread storms for
most of the CWA southeast of I-64. The next upper wave looks to
move in Thursday night and likely renews the storm and heavy rain
threat for again mainly the northwest parts of the area. The
third mid-level wave then approaches Friday night with another
bout of renewed and organized convection - still favoring the
northwest parts of the area. The latest model runs also suggest
that this third wave helps lift the boundary further north and may
spare much of eastern Kentucky the heavy convection for later
Friday and much of Saturday before the system bodily moving back
into the rest of the area on Saturday night into Sunday morning.
Once this last wave moves through the threat of heavy rains should
have ended for the area. Then cooler and drier air to follow
along with a potential for some frost and sub freezing
temperatures by Tuesday morning.

Despite the extremeness and climatological rareness of this
stalled pattern, most of eastern Kentucky is forecast to miss out
of the higher impacts owing to the heaviest rains forecasted to
stay north of the headwaters of our rivers. Even so, we need to
stay vigilant for a possible shift southeast in the heavy rain
axis and not let our guard down. However, as it stands now, it
seems increasing likely that the western part of the state and
confluence region of the Ohio and Mississippi rivers will see the
historic impacts from the repeated heavy rains of such extreme
durations while many of us here, especially those outside of the
flood watch, mostly note just an unseasonably warm stretch of
weather for early April interrupted occasionally by a bout of
mostly nocturnal showers and storms.

The changes to the NBM starting point consisted primarily of
adjusting the PoPs for ECMWF timing later in the period and adding
in hourly temporal resolution. Did also include more terrain
distinction to the low temperatures through Saturday morning for
our southeast zones.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 155 AM EDT WED APR 2 2025

VFR conditions are in place and will hold through the period under
mainly mid and high layers of clouds. Any stray shower activity
with a warm frontal passage on Wednesday will likely not affect
the TAF sites, with possible exception of SYM. Though surface
winds will be fairly light through sunrise, low-level southerly
flow slowly strengthens through the remainder of the night and
LLWS can be expected until mixing occurs mid-to-late morning.
Once mixed, we can expect gusts of 20-35 kts from the south
continuing through the afternoon.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 10 AM this morning to 8 PM EDT this evening
for KYZ044-050>052-058>060-068-069-079-080-083>085-106-108-111.

Flood Watch from this evening through Sunday morning for KYZ044-
050>052-058>060-068-069-079-080-083-084-104-106>109-111-112-114.

&&

$$

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