JKL issues Area Forecast Discussion (AFD) at Apr 23, 8:38 PM EDT103
FXUS63 KJKL 240038 AAA
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
838 PM EDT Wed Apr 23 2025
.KEY MESSAGES...
- Showers and thunderstorms will be around the area into tonight,
mainly limited to the south of the Mountain Parkway.
- More widespread showers/storms are possible on Thursday, Friday,
and Saturday, with the best chances on Friday afternoon and
Friday night when heavy rain is possible.
- Normal to above normal temperatures will be in place through
the upcoming weekend.
&&
.UPDATE...
Issued at 835 PM EDT WED APR 23 2025
Hourly grids have been freshened up based on recent observations
and radar trends. An outflow boundary has been moving gradually
north and east across the region with mainly an increase in
dewpoints as it passes. Instability has diminished following the
stronger late afternoon to early evening convection in the south.
Isolated showers were still occurring in portions of the
Cumberland Valley at this time. High resolution models suggest
some convection cannot be ruled out during the overnight hours in
a return flow/warm advective pattern. Overall, adjustments to
hourly grids at this time were to temperature and dewpoint trends
along with a lowering of thunder chances and confining them closer
to the TN border as the most recent thunder activity has been
nearer to the I-40 corridor in TN.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 450 PM EDT WED APR 23 2025
20Z sfc analysis shows weak high pressure nudging into the
northeast part of the state while return moisture and a boundary
is working into southern parts of the area. Accordingly, while the
north has stayed dry this afternoon, showers and a few
thunderstorms are popping over the Cumberland Valley - a couple
becoming strong enough for SPSs. Otherwise, temperatures have
climbed into the upper 70s and low 80s. Meanwhile, amid mainly
light and variable winds, dewpoints range from the mid 40s north
to the low 60s in the far south.
The models, and their individual ensemble suites, remain in rather
good agreement aloft through the short term period. They all
depict Kentucky between 5h ridging to the southeast and troughing
passing by to the north through the end of the week. This will
mean nearly zonal and somewhat slow mid level flow carrying weak
energy packets west to east through the region. Late in the
period, a shortwave trough heads into the western Ohio Valley with
a small uptick in 5h heights for eastern Kentucky and a southwest
tilt to the mid level flow. This will bring persistent moisture
flux into the area from an open Gulf, heading into the weekend.
The still small model spread supported using the NBM as the
starting point with minimal adjustments needed through the period
mainly to include just a touch of terrain distinction in the
evening for the northern fetches of the area tonight as well as
to incorporate more details in the PoPs from the CAMs guidance.
Sensible weather features increasing humidity for the area now
that the high pressure area is slipping away to the northeast.
This will mean warm days and mild nights along with a potential
for showers and a few thunderstorms but nothing too concentrated
considering the lack of upper support and/or strong sfc features.
Accordingly, the diurnal trends will dominate the PoPs into this
evening and on Thursday. Due to the moisture build up, expect
more uniform low temperatures for most of the area tonight and
area-wide on Thursday night.
The changes to the NBM starting point consisted primarily of
adding just a touch of terrain distinction to the temperatures
in the north this evening ahead of the more concentrated clouds.
As for PoPs - added some details from the CAMs consensus for much
of the area through Friday morning.
.LONG TERM...(Friday through Wednesday)
Issued at 400 PM EDT Wed Apr 23 2025
Shower and thunderstorm chances continue into Friday, as Eastern
Kentucky will remain firmly positioned within the warm sector out
ahead of an approaching storm system. Relative to the disturbance
responsible for Thursday's activity, Friday's forecast features
better mid/upper atmospheric support and a more clearly defined
surface cyclone. This favors more widespread convective coverage and
a prolonged period of rain chances stretching from Friday morning
through Saturday afternoon. As a midlevel trough approaches the Ohio
River Valley and the surface low pressure system moves into the
Great Lakes, flow in the lower half of the atmospheric column will
shift towards the southwest and intensify. This will lead to
increasingly effective moisture transport, but will also work to
mitigate the severe weather risk. PWAT values are forecast to rise
to well above climatological normals on Friday and remain elevated
overnight. The mean PWAT value resolved in the LREF ensemble
guidance is about 1.25 inches, but deterministic models suggest that
values could exceed 1.5 inches in western and northern portions of
the forecast area. This reinforces the notion that Friday's rain
could be heavy at times, and WPC has maintained the Marginal (Level
1/5) Excessive Rainfall Outlook for Friday and Friday Night across
all of Eastern Kentucky. Antecedent dryness will prevent widespread
significant river rises, but more localized urban and flash flooding
cannot be completely ruled out in any location that sees multiple
rounds of heavy rain between Thursday, Friday, and Friday night. The
current storm total QPF generally calls for between half an inch to
an inch of rain, with the potential for pockets of locally higher
totals noted. Remember, as always, turn around, don't drown!
The good news regarding Friday's wet forecast is that the associated
cloud cover will mitigate temperatures and thus instability. Mostly
cloudy skies throughout the day and the presence of precipitation in
the morning will limit the amount of diurnal warming that is
realized. Highs are forecast to remain in the 70s across the entire
forecast area, which will reduce the amount of energy for Friday's
storms. The highest CAPE values resolved in the currently-available
forecast guidance are near 1000 K/kg, and the primary threat with
Friday's activity will come from the previously-discussed heavy
rainfall. The enhanced cloud coverage will insulate Friday night's
temperatures to near 60 degrees, and rain chances will continue into
Saturday morning as the cold front approaches.
Saturday's forecast will fall in the form of a NW to SE gradient as
the aforementioned front finally pushes through. Our northwestern
counties in the Bluegrass region will be cooler in its wake, with
highs in the mid 60s and clearing skies by evening. South of the
Mountain Parkway, highs will remain near 70 degrees and the showery
activity will persist for longer. Overnight, a cooler continental
airmass begins to advect in as winds turn northerly. Expect lows in
the 40s, with ridge-valley temperature splits possible. Given the
wet grounds, fog could form in valley locations if the clouds clear
out. Confidence in this is not high enough to explicitly mention in
the grids for now, but valley fog could be included in future
forecast issuances.
Sunday's forecast temperatures look similar to Saturday's, but skies
will be much clearer in response to a nearby surface high. Midlevel
ridging and the surface high look to propagate eastward by early
next week, which will kickstart another warming trend ahead of the
next shower system. Highs are poised to warm into the 80s across the
entire forecast area by next Tuesday, which will prime the area for
renewed shower and thunderstorm chances as a cold front approaches
on Wednesday. Overall, April is poised to end on a warm and wet
note, and interests with outdoor springtime activities planned are
encouraged to remain weather aware over the coming days.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 815 PM EDT WED APR 23 2025
At issuance time, mainly mid and high clouds were moving across
the area with VFR reported. A few isolated showers were occurring
generally south of the TAF sites. Although isolated to scattered
showers cannot be completely ruled out during the first 12 hours
or so of the period under a return flow/warm advective pattern,
higher chances for convection arrive during the last 12 hours of
the period. These chances peak during the last 6 hours of the
period at that, coinciding with peak heating. VFR is expected to
prevail through at least the first 18 hours of the period. Brief
reductions to MVFR or lower are possible within the late in the
period convection, generally from around 18Z to the end of the
period. PROB30 groups were used to cover thunder chances at that
point. Winds will remain light and variable throughout the
period, except near showers and thunderstorms, where winds could
become gusty and erratic.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...JP
SHORT TERM...GREIF
LONG TERM...MARCUS
AVIATION...JP
Source:
JKL issues Area Forecast Discussion (AFD) at Apr 23, 8:38 PM EDT---------------
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