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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KJKL 171831
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
231 PM EDT Wed Apr 17 2024

.KEY MESSAGES...

- Chances for showers and a few storms are in the forecast through
  tonight, and also Thursday night into Friday evening. Chances
  peak today and this evening 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...
-- Changed Discussion --
Issued at 231 PM EDT WED APR 17 2024

Clouds and showers have held down temps over southern portions of
the forecast area. Even though showers are ending, it does not
seem like there will be enough time to recover to the earlier
forecast max temps, and they`ve been revised downward.

UPDATE Issued at 1110 AM EDT WED APR 17 2024

Showers have moved into the region from the west, but the northern
extent has been diminishing. In light of radar trends, have
lowered today`s POP for our northern counties, raised it slightly
in the south, and have foregone thunder until the potential for
additional development late in the day in our northern counties.

UPDATE Issued at 735 AM EDT WED APR 17 2024

Did a quick update to the forecast for the near term to fine tune
the PoPs and thunder chances per the latest radar and CAMs trends.
Did also incorporate the current obs and tendencies for the T/Td
grids. These minor adjustments have been sent to the NDFD and web
servers.
-- End Changed Discussion --

&&

.SHORT TERM...(Today through Thursday)
Issued at 500 AM EDT WED APR 17 2024

08Z sfc analysis shows Kentucky between a deep area of low
pressure to the northwest while high pressure is well off to the
southeast. This is keeping a somewhat tight pressure gradient
through the area making for a well mixed boundary layer and winds
from the south to southwest at around 10 mph with occasional gusts
to 20 mph. The result is a very mild night with temperatures
holding in the low to mid 70s most places though a couple of the
most sheltered spots in the east have decoupled into the lower
60s. Meanwhile, under mostly cloudy skies with a few patches of
light showers around, dewpoints have managed to dry out down to
the mid and upper 40s for the majority of the obs sites. We will
see mainly light showers work into the area from the west through
the first part of the morning likely weakening and dissipating as
they arrive. The more robust of these showers may also bring down
some stronger wind gusts in the 30 to 35 mph range.

The models, and their individual ensemble suites, remain in very
good agreement aloft through the short term portion of the
forecast. They all depict a weakening closed low trough lifting
northeast through the northern Great Lakes and brushing by
Kentucky today. This has already led to 5h heights falling this
morning and continuing into the afternoon as the core energy with
the trough moves by to the north - beefiest this afternoon
cutting east through Ohio. The mid level flow then flattens out
this evening before influence from ridging over the Gulf pushes
heights back up over the area into Thursday - also out ahead of a
very large trough grinding through the Northern Plains and into
the Upper Midwest by that evening. This will have the effect of
tilting the flow more southwesterly for eastern parts of the
state by late day, Thursday. Due to the continued rather small
model spread, the NBM was used as the starting point for the
grids, though along the addition of CAMs guidance for the PoPs
through tonight.

Sensible weather features another breezy and warm day - but a
touch cooler than the past few on account of extra cloudiness and
a period or two of showers. Most of the CAMs suggests that the
morning activity will fade out by afternoon hindering the column`s
destabilization and recovery. So that, despite a promising set up
for storms, the question of initialization remains the biggest
issue for our late day convection chances. As such, eastern
Kentucky will have a conditional threat of severe storms should
instability build enough with daytime heating and a trigger
mechanism develops. The most likely severe scenario is for a few
storms to redevelop late in the day for northern parts of the area
either along a sagging cold front or on any thunderstorm outflow
boundaries that may push in from the north later this evening.
Given the limited model support the specifics of the forecast
remain uncertain but the potential is there for a more stormy
evening than currently depicted. Once any activity fades out
later tonight we will likely be in a dry lull through most of
Thursday ahead of the next system approaching from the Plains.
This will also mean more sunshine and a rebound in high
temperatures - back into the low to mid 80s.

The main adjustments to the NBM starting point were centered
around incorporating the consensus CAMs ideas for PoPs and pcpn
timing today through tonight and accounting for the conditional
threat of storms this evening. Again only made some minor
adjustments to temperatures based on terrain tonight as well as
taking highs up a notch today.

.LONG TERM...(Thursday night through Tuesday)
Issued at 506 AM EDT WED APR 17 2024

A large trough of low pressure moving eastward along the southern
Canadian border will be the primary weather feature in the extended.
This system will move slowly eastward Thursday night through
Saturday, before finally moving out into the North Atlantic Saturday
evening. In the meantime, another weaker trough of low pressure is
expected to move through the southern stream Sunday and Monday and
eventually offshore of the southeastern CONUS Monday evening. A
northern stream shortwave is then expected to dive southeastward out
of Canada, through the Great Lakes and then across the Ohio Valley
Monday night through Wednesday. Finally, a strengthening ridge of
high pressure will be taking shape over the southwestern CONUS
Tuesday night into early Wednesday. Decided to use data from the GFS
Ensemble for system evolution and movement with CONSRAW used for
modifying temperatures, dewpoints, and winds in the extended.

We are expecting showers and scattered thunderstorms to move through
eastern Kentucky Thursday night and Friday, as surface cold front is
pushed through the region by is parent southern Canada trough on its
eastward trek. Locally heavy rainfall may occur with a few of the
storms as they move through. This first round of rain should come to
a close late Friday, as the surface front moves off to our east and
the upper trough continues on its journey through southeastern
Canada. After this first big system has moved on, a ridge of high
pressure will then settle over the region Friday night through
Saturday night, and will bring dry but much cooler weather to the
are for a few days. In fact, cold air advection should be robust
enough to allow temperatures to top out only in the upper 50s to mid
60s over the weekend.

A second area of low pressure is forecast to move through the lower
Tennessee Valley on Sunday, and could bring scattered showers and a
few storms to portions of eastern Kentucky on Sunday, primarily along
the Tennessee and Virginia borders. After the southern stream system
has moved off to our east Sunday evening, another ridge of high
pressure will be poised to settle over the region to begin the new
work week. We will again see a short period of dry weather and
cooler than normal temperatures. Our highs Monday and Tuesday will
be only slightly higher than what we see over the weekend, with max
values in the mid 60s to lower 70s on tap. Finally, toward the end
of the period, Tuesday and Tuesday evening, a fast moving short wave
moving by to our north could bring scattered showers and few more
storms to eastern Kentucky. This period of rain looks to short
lived, with any rain exiting the area by late Tuesday evening. Winds
might become brisk and gusty Tuesday, as the shortwave moves quickly
through the area.

&&

.AVIATION...
-- Changed Discussion --
(For the 18Z TAFS through 18Z Thursday afternoon)
ISSUED AT 231 PM EDT WED APR 17 2024

Scattered showers and areas of MVFR ceilings were present over
south central and southeast KY at the start of the period.
Elsewhere, VFR conditions prevailed. The showers will end and
prevailing VFR conditions are forecast area wide by early this
evening. There is a small potential for thunderstorms to develop
early this evening near and northeast of a line from KSYM to
KPBX, and this would result in localized sub-VFR conditions.
Should this activity develop, it would depart and leave dry
weather overnight. Localized vally fog can`t be ruled out tonight
into early Thursday, but it`s not expected to affect TAF sites.

Southwest winds will gust 20-30 mph this afternoon, but will
diminish this evening.
-- End Changed Discussion --

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

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