168
FXUS63 KJKL 041737
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
137 PM EDT Fri Apr 4 2025

.KEY MESSAGES...

- Multiple rounds of heavy rain and thunderstorms will affect
  eastern Kentucky through Sunday.

- Warm temperatures will last through Saturday, followed by much
  colder air arriving to start the new week.

- Frost and/or freezing temperatures are forecast for most places
  Monday night and Tuesday night.


&&

.UPDATE...
Issued at 912 AM EDT FRI APR 4 2025

The frontal boundary continues to settle very slowly to the
southeast while convection trains from west southwest to east
northeast while very slowly pivoting more west to east. This
likely is a harbinger of the boundary stalling and then beginning
to lift back to the north later this morning. Flash Flood and
Areal Flood Warnings have been issued for northern Pulaski to
northern Pike Counties and northward as many locations have picked
up 1 to 2 inches since midnight. However, localized dual pol
radar estimates have reached to around 4 inches in locations where
training has been most persistent in northern Rockcastle and
western Jackson counties (it does appear the the radar may be
overestimating slightly). Once the widespread rain lifts north,
there could be a window this afternoon for discrete supercell
development. We will continue to monitor closely.

&&

.SHORT TERM...(Today through Saturday)
Issued at 604 AM EDT FRI APR 4 2025

A stream of moisture from the Gulf of America continues to pour into
the Lower Ohio Valley, supporting repeated rounds of torrential
downpours this morning. The latest regional radar mosaic shows this
shower and thunderstorm activity just poleward of a southward
sagging boundary extending from a weak wave of low pressure over
the Mid-Atlantic through the the Shenandoah Valley then more
westerly to along the Virginia/Kentucky border and then down into
the Tennessee Valley. Temperatures north of the boundary are
generally in the 50s across most of the Commonwealth, except in
the far southeast where thermometers are as warm as the 70s. The
latest mesoanalysis shows a strong low-level warm conveyor belt
(up to 50 knots at 850mb) feeding copious moisture and weak
instability up over the boundary and then blossoming into showers
and thunderstorms upon reaching the level of free convection.
Ascent is aided by divergence in the right entrance region of a
250mb jet over the Eastern Great Lakes and St. Lawrence Valley.

This setup will continue force a southeastward sinking line of
training convection through late morning. While most locations
northwest of a Somerset-to-Jackson-to-Inez line will see 0.5 to
1.50 inches from midnight through midday, locations along where
the line eventually stalls could see localized amounts of up to 4
inches under the most extreme training. The boundary will then
slowly lift back north as a warm front thereafter with a general
lessening in precipitation coverage and intensity as forcing for
ascent diminishes as a new wave of low pressure develops over
Texas and ejects northeast into Arkansas. By mid-afternoon, most
if not all of eastern Kentucky will once again reside in the warm
sector with temperatures surging back into the lower and mid 80s
south of the Mountain Parkway and 70s in most locations further
north. Guidance indicates that moderate to even locally high
instability could develop this afternoon across portions of the
forecast area but the only forcing mechanism may end up being a
differential heating boundary. If convective initiation occurs,
the resulting storm cells will have access to more than ample
instability (MLCAPE 2000 J/kg+) and shear (EBWD 50+ kts) to become
sustained supercells with an attendant damaging wind, large hail,
brief tornado threat -- but this risk is conditional and
confidence in this occurring is low at this time.

Heading into tonight, the frontal boundary is likely to sag back
south as the aforementioned wave of low pressure tracks north of
the Ohio River and into the Eastern Great Lakes. This could cause
another round of convection to sink toward the I-64 corridor late
in the night and possibly further but confidence in the front`s
southeastward progress is low at this time. If instability remains
underutilized from conditional daytime convection, strong to
severe storms could occur overnight, most likely in the northwest
counties as the line sags south. Temperatures are forecast to
settle into the lower and middle 60s overnight. The line is then
once again expected to slowly lift north again during the day on
Saturday as the final and strongest wave of low pressure with this
stormy pattern organizes over the Southern Plains. The latest hi-
res guidance suggests that the boundary may not fully lift north
of our Bluegrass counties before the upper level trough and final
low pressure system finally start push this whole mess eastward at
the beginning of the long-term. Temperatures are forecast to once
again warm into the lower to middle 80s to near 90 south of the
Mountain Parkway on Saturday afternoon but remain the upper 70s to
lower 80s at most locations further north.

.LONG TERM...(Saturday night through Thursday)
Issued at 422 AM EDT FRI APR 4 2025

The forecast period begins with a surface low lifting through the
Ohio Valley and as that happens, the associated cold front will
slowly track toward the CWA through the late hours of Saturday and
through the day Sunday before exiting late early Monday morning. The
best forcing for this front will be back toward central Kentucky;
however, forecast soundings for Saturday afternoon into Saturday
evening show the potential for some storms to push severe limits.
Showers and storms will persist through the overnight hours and
through the day Sunday and the SPC has a Marginal Risk for Sunday as
a renewed threat for strong to severe storms will exists for areas
mainly southeast of a line from Martin County to Wayne County. Also,
forecast PWs are as high as 1.50" and in combination with saturated
soils and convection, widespread hydro issues can be expected again
on Sunday. Which is highlighted in the Day 3 Slight Excessive
Rainfall Outlook from the WPC.

The front is forecast to exit the area by early Monday morning with
post-frontal CAA building into the region. These colder temperatures
will set the stage for the potential for rain/snow showers Monday
night as another surface low moves through the Great Lakes and drags
another weak, mostly dry cold front through the CWA. Behind the
second front, high pressure will build into the region, but CAA and
clear skies will allow for frost development Tuesday morning and
again Tuesday night into Wednesday morning. Surface high pressure
remains through midweek before a clipper system dives out of the
northern Rockies toward the Commonwealth. This brings a renewed
chance for PoP beginning late Wednesday evening through the
remainder of the period.

Overall, the forecast period will feature the stalled boundary,
that`s been plaguing the region, to finally move out of the area as
a surface cold front on Monday. Weak surface high pressure will
build into the region but another, mostly dry cold front will bring
rain/snow showers late Monday night into Tuesday. Widespread near
freezing temperatures and widespread frost can be expected Tuesday
and Wednesday mornings before another system moves into the region
for late Wednesday night. Lastly, the period will start with below
average temperatures behind the front but will quickly rebound by
the middle of the week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 137 PM EDT FRI APR 4 2025

VFR conditions were occurring at all terminals to begin the
period, with the exception of KSYM where LIFR conditions in rain
and fog were occurring. For the forecast, expect more widespread
rain to lift north, with isolated to scattered showers and
thunderstorms developing and moving northeast across the area
through this afternoon as a stationary boundary lifts north as a
warm front. Generally VFR conditions are expected tonight, with
LLWS developing as the region lies under a strengthening low-level
jet.

Conditions Saturday morning into the afternoon will be highly
conditional on whether upstream convection in western and central
Kentucky moves into eastern Kentucky or remains west of the area.
Unfortunately, models are split 50/50 on whether there will be
convection moving into the area from the west. If the dry scenario
is realized, VFR conditions with just mid-level clouds can be
expected, but MVFR or lower conditions will be possible within any
showers and storms that move across the area. For now, given low
confidence in which scenario may occur, the TAFs are covered with
PROB30 groups. Regardless of which scenario occurs, by early
afternoon Saturday southwest winds will begin to increase to 10 to
15 kts with gusts possibly as high as 20 to 25 kts.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Sunday morning for KYZ044-050>052-058>060-
068-069-079-080-083-084-104-106>116-119-120.

&&

$$

UPDATE...GEERTSON
SHORT TERM...GEERTSON
LONG TERM...VORST
AVIATION...CMC