324
FXUS63 KJKL 031317
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
917 AM EDT Thu Apr 3 2025

.KEY MESSAGES...

- Strong to severe thunderstorms are possible again this afternoon
  into this evening, especially south of the I-64 corridor.

- Multiple rounds of heavy rain and thunderstorms will affect
  eastern Kentucky through Sunday - especially northwest parts of
  the forecast area where between 3 and 7 inches of rain is
  possible.

- Temperatures will be warmer than normal through Saturday before
  well below normal temperatures follow for the new work week.

- A hard freeze appears increasingly likely for most of eastern
  Kentucky next Tuesday night into Wednesday morning.

&&

.UPDATE...
Issued at 849 AM EDT THU APR 3 2025

The line of storms has weakened and settled to along a line from
Inez to Barbourville (nearly parallel to the deep southwesterly
flow aloft). Supercells continue to stream northeast out of Middle
Tennessee along the edge of the boundary but are quickly sheared
out as they encounter very little lingering instability over
eastern Kentucky. This will likely be the case for the remainder
of the morning, thus the Tornado Watch was cancelled early. The
boundary is expected to drift slowly back to the north this
afternoon, allowing for surface heating over southeastern
Kentucky. Hi-res CAMS continue to show potential for a resurgence
in strong supercell thunderstorms riding along the boundary once
instability recovers this afternoon. These storms will need to be
monitored closely as they will pose a threat for damaging winds,
large hail, and even tornadoes. Aside of the the renewed severe
threat, showers and storms continuing to train southwest to
northeast over the same locations for multiple hours will likely
lead to eventual flooding concerns, particularly in the Flood
Watch area (where most locations observed 1 to 2 inches of rain
earlier this morning).

&&

.SHORT TERM...(Today through Friday)
Issued at 125 AM EDT THU APR 3 2025

Extremely mild temperatures are in place across eastern Kentucky
early this morning. Thermometer readings range from the mid to upper
70s across all but the higher elevations. South to southwest wind
winds remain gusty to between 20 and 35 mph. Dew points have
risen into the lower/mid 60s west of I-75 and over much of the
Bluegrass while dew points remain in the mid/upper 50s at most
locations further east. Looking upstream, a potent squall line
responsible for many severe thunderstorm and tornado-warned
storms over the last several hours stretches from Wilmington, OH
southwestward through Frankfort, KY to Bowling Green and beyond.
This line of intense thunderstorms is racing out ahead a cold
front extending southward from an ~992 mb low over Lake Superior
southward across Lake Michigan through the Mid-Mississippi Valley.
This boundary lies between a 500H trough over the western CONUS
and a ridge over the eastern CONUS. An extremely moist air mass
(near to exceeding climatological maximums) is feeding into the
Commonwealth on a 60-70 kt 850mb warm conveyor belt jet. Though
the line is outrunning its upper level support, it has generated a
robust cold pool which will continue to propel the the QLCS into
eastern Kentucky through sunrise. Compared to locations further to
our south west, analyzed instability is more marginal early this
morning, approximately 200 to 600 J/kg of MLCAPE (northeast to
southwest) and that is offset by 75 to 200 J/kg of MLCIN (north to
south). While the instability fields are marginal, effective
shear upwards of 55 kts should help the line maintain better than
the instability alone would typically suggest. Strong to damaging
straight-line winds with bowing line segments appear the main
threat, with DCAPE values of 700 to 1,000 J/kg ahead. A brief
spinup tornado is also possible with the greatest chance for that
in the recently issued Tornado Watch.

The weakening QLCS outflow is expected to sink through southeast
Kentucky to near the Kentucky/Virginia border by or shortly after
12z. Additional showers and storms are likely to develop along the
remnant outflow boundary throughout the daylight hours and could
train repeatedly over the same locations. HREF LPMM continues to
support a widespread 0.5 to 2.0 inches of rain over most of the
watch area through 8 PM this evening; however, localized swaths of
rainfall nearing 4 inches are depicted in high-end scenarios. The
higher end amounts would be sufficient to cause minor and poor
drainage flooding and substantial rises on larger creeks, streams,
and rivers. In addition the the growing threat for flooding, there
will continue to be a threat of severe thunderstorms, primarily in
the form of supercells (potentially tornadic) that could develop and
ride the remnant outflow boundary from southwest to northeast. The
eventual position of the stalled outflow boundary is favored to
generally be along or just north of the Hal Rogers Parkway/KY-80
corridor. South of the boundary, temperatures are expected to
warm in the lower and middle 80s. North of the outflow boundary,
afternoon temperatures are forecast to be much cooler, mainly in
the upper 60s to lower 70s.

For tonight and Friday, anticipate that the trough over the western
CONUS will continue to amplify with a compensatory strengthening
over the ridge over the eastern CONUS. As a result, the boundary
over eastern Kentucky will gradually retreat back toward the Ohio
River, causing rain chances to wane slowly from south-to-north.
Locations near and north of the Mountain Parkway are most favored
to receive additional heavy rainfall, where an another widespread
1 to 2 inches of rainfall is likely. Further localized rainfall
amounts of 4 inches cannot be ruled out. Tonight`s minimum
temperatures are forecast to range from the mid 50s near/north of
I-64 up the mid 60s near/south of the Hal Rogers Pkwy/KY-80
corridor. Greater amounts of sunshine are anticipated for most
locations on Friday with high temperatures forecast to range from
the mid 70s north of I-64 to the mid and upper 80s south of the
Mountain Parkway.

.LONG TERM...(Friday night through Wednesday)
Issued at 550 AM EDT THU APR 3 2025

The long-term period will open 00z Friday evening with a high
amplitude 500H trough extending from the Arctic down into Central
Canada and then west southwest to over the Desert Southwest.
Meanwhile, an ~592 dam high is situated just off the Southeast US
Coast. In between these two synoptic scale features, a baroclinic
zone manifests as a warm frontal boundary draped from the eastern
Virginia/North Carolina border, through the Central Appalachians,
across northern Kentucky and then southwest into Arkansas where
there are one or two subtle waves of low pressure. A stationary
boundary extends southward from that lower pressure into Texas. A
secondary cold front extends from a low over the Hudson Bay
southwestward through the Upper Midwest and into the Central
Plains.

The upper level trough over the western CONUS will finally begin to
eject eastward Friday night and Saturday. As the lead wave of low
pressure lifts northeast Friday night, it will pull the warm front
north of the JKL forecast area, leading to only some low chances for
a shower or thunderstorm for toward the I-64 corridor Friday night.
As that wave of low pressure departs into the Eastern Great Lakes on
Saturday, it will finally drag a cold front across the Eastern
Kentucky Coalfields Saturday night. The environment along the
boundary, and just ahead of it in the warm sector, appears
favorable for severe thunderstorms, warranting a Day 3 Marginal/Slight
Risk of severe weather over much of the area. This boundary will
also bring the final widespread 1 to 2+ inch rainfall later
Saturday into Sunday. The break in the rainfall Friday night into
Saturday should allow high water issues to recede somewhat before
this culminating round of rain. Rain chances diminish late Sunday
and Sunday night with the passage of the secondary cold front. If
skies clear out sufficiently Sunday night, then some patchy frost
is certainly a possibility, especially toward the Bluegrass.

Heading into the new work week, the upper level troughing will
become established over much of the eastern CONUS. A northern stream
low pressure system passing over the Great Lakes will drop a
moisture-starved cold front through the Commonwealth on Monday
night. If there is sufficient low-level moisture, any light
precipitation with the frontal boundary could mix with some
snowflakes come late Monday night and early Tuesday as 850mb
temperatures drop to between -5 and -10C. This will set the stage
for a freeze in many locations on Monday night into Tuesday. High
pressure builds in by Tuesday night bringing better conditions
for radiative cooling and the likelihood for a widespread hard
freeze. Southerly return flow behind the departing high pressure
will finally bring a warming trend for Wednesday and beyond.

In sensible terms, look for drier conditions across much of the area
Friday night into Saturday, though at least scattered showers and
thunderstorms are expected to persist near and northwest of I-64.
It will remain unseasonably mild for early April with low
temperatures in the lower to middle 60s and highs in the mid to
upper 80s, except upper 70s north of I-64. Rain returns, along
with the possibility of a few severe thunderstorms, Saturday night
with lingering rain/thunder chances for most of the Sunday before
departing late Sunday/Sunday night. Temperatures follow a
nondiurnal cooling trend such that frost is possible in those
locations which see clearing skies by early Sunday night. Monday
is forecast to be cooler with high temperatures in the 50s. Even
colder air arrives with a few showers and perhaps even some flakes
Monday night as temperatures fall back into the upper 20s and
lower 30s. Tuesday`s high temperatures are expected to remain in
the 40s. Clear skies and light winds set the stage for widespread
lows ranging in the mid to upper 20s for most locations on Tuesday
night. Milder air returns on Wednesday with temperatures trending
back toward climatological norms.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 810 AM EDT THU APR 3 2025

Storms are training southwest to northeast along a frontal
boundary laid out from roughly BYL to PBX at TAF issuance.
Northwest of the leading edge of this boundary, a mixture of VFR
to IFR conditions are occurring under widespread rain with
embedded heavier showers and thunderstorms. Through the remainder
of the TAF period, MVFR to IFR conditions are likely to occur
with the heavier activity as the frontal boundary slowly lifts
back to the north. There will also be a renewed threat for severe
thunderstorms along the frontal boundary this afternoon with
damaging winds, large hail and isolated tornadoes possible.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Flood Watch 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...GEERTSON
LONG TERM...GEERTSON
AVIATION...GEERTSON