Area Forecast Discussion Issued by NWS Jackson, KY
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000
FXUS63 KJKL 162017
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
417 PM EDT Tue Apr 16 2024
.KEY MESSAGES...
- Chances for showers and a few storms are in the forecast today
through Wednesday night, and also through next weekend. Chances
peak Wednesday and Wednesday night when the strongest storms
are possible.
- Well above normal temperatures will be in place over the area
through Thursday, with readings peaking in the upper 70s to low
80s each day, or about 10 degrees above normal. Cooler weather
follows for the weekend.
&&
.UPDATE...
Issued at 204 PM EDT TUE APR 16 2024
Interesting set up this afternoon. Band of light precipitation is
moving eastward across eastern Kentucky, gradually dissipating as
it tracks eastward. Some type of residual surface boundary
(convective?) is lifting north-northeast across portions of the
area, but mainly across VA/WV, brushing far eastern portions of
our forecast area. This boundary is kicking off showers and
thunderstorms across the area and will likely continue to do so
over our eastern most zones. Made adjustments to PoPs for this and
also tweaked hourly temps to try and capture the band of clouds
and light precip moving across the area. No major changes to the
forecast other than the increase in PoPs for this afternoon,
especially across our east. Will update the zones one last time
for these most recent trends, impacting mainly our east.
UPDATE Issued at 715 AM EDT TUE APR 16 2024
Just a quick update to the forecast to add in the latest obs and
trends for the T/Td/Sky grids. These small adjustments have been
sent to the NDFD and web servers.
&&
.SHORT TERM...-- Changed Discussion --
(Today through Wednesday)
Issued at 520 AM EDT TUE APR 16 2024
08Z sfc analysis shows a wavy west to east front has dropped
midway through eastern Kentucky connected back to a developing
area of low pressure over the Central Plains. This boundary
spawned a few storms last evening and even now has a cluster going
to the east of the state. It has also kept skies mostly cloudy and
wind stirred enough to limit much of a ridge to valley temperature
split. Specifically, readings are generally in the mid to upper
60s on the hills while some mid to upper 50s are found in a few
of the sheltered spots. Meanwhile, amid light southerly winds,
dewpoints have come up into the mid and upper 50s across the
board - providing some of the fuel for the earlier storms. Despite
the higher dewpoints, the clouds and light winds have been enough
to keep any fog to a minimum.
The models, and their individual ensemble suites, continue to be
in broad agreement aloft through the short term portion of the
forecast. They all depict the approach of a closed trough low from
the Plains with downstream ridging over Kentucky through most of
the day. The mid level flow transitions to southwesterly this
morning as a lead impulse passes through. Additional impulses
arrive tonight with height falls at 5h commencing as the trough
brushes by to the northwest and then to the north on Wednesday.
The core of the energy with this low does pass on Wednesday
afternoon affecting the northern portion of the JKL CWA. By
evening, the mid level flow will be flattening with a lull in any
weak short waves moving overhead. Given the persistent small
model spread, the NBM was used as the starting point for the grids
along the addition of CAMs guidance for the PoPs through
Wednesday.
Sensible weather features another warm couple of days, though
temperatures will likely be mitigated on Wednesday on account of a
increased clouds and a couple of rounds of convection. For today,
the boundary returns north with rising heights aloft working to
limit convection and even its initialization. The latest CAMs
suggests that some early showers today will hinder the ability of
the area to destabilize for better storm development this
afternoon. Similarly, the approach of the sfc low`s occluded front
tonight would also allow for showers and a stray thunderstorm
around, but with timing that would harm the potential for storms
later Wednesday even as we reach peak heating. For this reason, it
seems, SPC has pulled the slight risk area back to the northwest
of the JKL CWA and closer to the center of the low both at the sfc
and aloft.
The main adjustments to the NBM starting point were generally
related to the consensus CAMs ideas for PoPs and timing today
through Wednesday. Only made some minor adjustments to
temperatures based on terrain tonight on account of the increased
cloud cover and pcpn timing.
.LONG TERM...(Thursday through Tuesday)
Issued at 417 PM EDT TUE APR 16 2024
The period begins with the mid-level short wave toward the
Midwest and a surface low developing and moving northeast along
the cold front toward the Midwest. Meanwhile, in the Ohio Valley
ensembles and deterministic guidance show good indication of mid-
level height rises and warm front lifts northward as the
previously mentioned low tracks northeast. Given the rising
heights and mostly sunny skies we will see afternoon high
temperatures soar into the upper 70s to lower 80s on Thursday,
with ensembles showing about a 30 to 40 percent chance of greater
than 80 degrees for highs. The 80s don`t seem to hard to achieve
given the ensemble and deterministic forecast soundings showing
dry lower level. Then unsettled weather moves east, as guidance is
in good agreement on the front advancing eastward Thursday night
into Friday. This will lead to a 70 to 80 percent chance of rain
Thursday night, with about a 20 to 40 percent chance of
thunderstorms. There is some question as to how much instability
we can maintain through the evening and overnight that leads to a
fair amount of uncertainty on if we could see a stronger storm.
The shear isn`t the best, but effective shear is still around 30
to 35 knots which could lead to some organization. SPC does have a
portion of the CWA in the marginal risk and that seems reasonable
given the fair amount of uncertainty.
Friday, the cold front will advance eastward across eastern
Kentucky by Friday afternoon, as a high pressure noses eastward
from the Plains. The winds will veer from the southwest to
northwest through the day. The chances of rain through the
afternoon will be around the 60 to 80 percent range. This cold air
advection, clouds, and rain early in the day will lead to highs
in the upper 60s to lower 70s. The showers and perhaps
thunderstorm could extend into the evening, but this should tapper
off quickly into the 20 percent range. This as high pressure
continues to nose east into the Ohio Valley and will lead to dry
weather through Saturday night. The question in terms of frost
would be if we can clear out enough or long enough Saturday night.
Given this opted to keep out of the grids for now.
The ensembles and deterministic begin to diverge a bit on a
southern stream system by Sunday. The NBM keeps a small chance of
PoPs in the far southeast, but some guidance suggest it will be
dry Sunday and even if most of the CWA will remain dry. Then high
pressure finally builds east across the Ohio Valley and a
shortwave advances southeast into the Lower Ohio Valley where
guidance seems to have better agreement. Once again, we could see
a few 30s in the more sheltered valleys, but uncertainty remains
on if we could see cloud cover. Then yet another mid-level wave
advances east By Tuesday, but once again ensembles and
deterministic diverge, so stuck with slight chance values from
the NBM generally in northeast Kentucky.-- End Changed Discussion --
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 204 PM EDT TUE APR 16 2024
VFR conditions will prevail through the TAF period. There will be
a small chance for a shower or storm through the area this
afternoon and against late tonight or early Wednesday morning. Winds
will be southerly in nature, generally around 10 kts or less with
occasional higher gusts, particularly this afternoon and then
again tomorrow. Some LLWS will be possible late tonight from the
south to southwest at about 40 kts as well.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...RAY
SHORT TERM...GREIF
LONG TERM...DJ
AVIATION...RAY