394
FXUS63 KJKL 170411
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1211 AM EDT Tue Sep 17 2024

.KEY MESSAGES...

- A cool-down arrives for Tuesday, with a warming trend expected
  through the remainder of the week.

- A potential for showers arrives from the east tonight into
  Tuesday. Additional shower (and possible thunderstorm) chances
  will occur through midweek.

&&

.UPDATE...
Issued at 1211 AM EDT TUE SEP 17 2024

Only minor changes have been made as obs were blended into the
forecast.

UPDATE Issued at 819 PM EDT MON SEP 16 2024

Have updated sky cover to go with a little bit faster increase in
high clouds tonight. Otherwise, the forecast is unchanged.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 505 PM EDT MON SEP 16 2024

Observations and satellite show bright sunshine fading this
afternoon as a cloud shield, associated with low pressure coming
ashore near Myrtle Beach, SC, advances westward. Thermometers show
temperatures ranging from the mid 70s to around 80 near/east of
US-23 to the mid 80s west of I-75 and near/north of I-64. At
elevations above 2,500, temperatures are mainly in the 60s.
Regional radar has at times shown some weak reflectivity echoes
associated with a thicker mid-level cloud deck drifting into far
eastern Kentucky, perhaps leading to some virga. Dewpoints
range from the 40s near and northeast of KY-15 to mid 50s further
southwest.

This first surge of Atlantic moisture from the coastal low will
raise PWATs back above 1 inch across the two tiers of counties
adjacent to VA and WV this evening. Most echoes on radar should be
virga, though the strongest of echoes could perhaps lead to a few
sprinkles, warranting mention in Pike and adjoining county
forecasts. The cloud shield will overspread the remainder of the
JKL CWA this evening. As the coastal low drifts toward the
Southern Appalachian mountains overnight, a stronger surge of deep
moisture (PWATS above 1.5 inches) and attendant 500H vorticity
lobe crosses over the Central Appalachians, likely causing a light
to moderate rain band to reach the VA-KY border around or after
6z. Tonight`s lows are forecast to range from the mid 50s to lower
60s tonight, a few degrees warmer than last night due to cloud
cover and, for some, rainfall.

The deeper moisture will continue to spread westward during the
morning hours on Tuesday but lingering dry air over Central
Kentucky and diminishing forcing aloft will likely lead to a sharp
cutoff in rainfall, perhaps near/north of I-64 and near/west of
I-75. Once the initial band clears the forecast area during the
first part of the day Tuesday, additional spotty showers (20-50%
chance, highest northeast of KY-15) are possible during the
afternoon. A rumble of thunder cannot be entirely ruled out as
well, though abundant cloud cover will limit daytime heating and
instability. The lack of sun will also keep maximum temperatures
noticeably cooler, mainly in the upper 60s to mid 70s.

The dissipating coastal low`s remnants continue to approach on
Tuesday night, keeping plenty of cloud cover and a low probability
(mainly under 30% chance) of showers over the area. Overnight
temperatures remain mild, holding mainly in the lower to middle
60s.

Rainfall totals through Tuesday night are forecast to range
from 0.5 to 0.7 inches near the Virginia/Kentucky border to 0.1
inch or less west of I-75 and north of I-64. Given ongoing dry
conditions across much of eastern Kentucky, this rainfall should
be highly beneficial.

.LONG TERM...(Wednesday through Monday)
Issued at 427 PM EDT MON SEP 16 2024

The models start off in good agreement through the remainder of the
work week. By the start of the extended on Wednesday morning, the
low that is currently affecting the southeast Atlantic Coast will
have moved inland and will be sitting over the Southern Appalachian
region. Here the troughing will remain for the next few days. With
deep north flow across the region, this will result in cooler
temperatures for a couple of days. The system to our east will also
provide a daily chance of showers and thunderstorms. These chances
will increase as you head farther east towards West Virginia and
Virginia. Not overly impressed with the instability however. Models
have the precip ending by Friday, as the system starts to pull
farther northeast. Despite continued northerly flow aloft,
temperatures will begin moderating a bit warmer each day, leading to
a warming trend to end out the work week Thursday and Friday.

For the weekend, there is still quite a bit of disagreement in the
models. Both the GFS and ECMWF show rising heights across the region
as a strong upper level ridge builds in the from the far southern
Conus. However, with the trough now just off the Atlantic Coast, the
ECMWF tries to keep some level of troughing across the eastern
portion of the state through the weekend, while the GFS keeps a
ridge in place instead. The ECMWF continues to strengthen this
system over the Atlantic, while the GFS takes it much farther north
and away from the Mid-Atlantic Seaboard. For sensible weather, this
pattern would promote a potential for isolated/scattered showers and
thunderstorms in Kentucky according to the ECWMF solution.
Meanwhile, the GFS is dry. By Monday, the ECWMF has the system and
moisture really ramping up across the Atlantic, pulling moisture
eastward and away from Kentucky. However, the GFS shows a shortwave
and potential frontal system nearing the state from the west, which
would increase precip during the day Monday. Very different
solutions with not a lot of confidence in either. As such, just
stuck with the NBM at this point. It is favoring a dry solution
through the weekend, then introduces slight chance pops again on
Monday - closer to the GFS solution. This is very late in the
period, granted, so do expect these model solutions and therefore
the forecast to change. The current forecast is for temperatures in
the low to mid 80s during the weekend, warmest on Saturday - however
this may also change some as one model solution becomes favored.
Don`t expect a huge increase or decrease, but possibly a few degrees
either way.

Overnight temperatures should remain fairly steady through the
extended with clearing skies and light winds allowing for good
radiational cooling. Lows will generally be in the mid and upper
50s, coolest in the deeper valleys.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 806 PM EDT MON SEP 16 2024

VFR conditions were present to start the period. High clouds were
slowly spreading westward across the region. They will lower and
thicken with time. Light rain is forecast to develop from
southeast to northwest overnight and early Tuesday. This will lead
to worsening conditions, with a mix of MVFR and IFR conditions
developing northwestward over the region from about 09Z-18Z. Winds
will mostly be from the northeast at less than 10 kts.

&&

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

$$

UPDATE...HAL
SHORT TERM...GEERTSON
LONG TERM...JMW
AVIATION...HAL