412
FXUS63 KJKL 182025
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
425 PM EDT Wed Sep 18 2024

.KEY MESSAGES...

- Additional shower (and possible thunderstorm) chances will
  occur through Thursday.

- A warming trend will lead to temperatures around 10 degrees
  above normal over the upcoming weekend.

- Active weather returns for the 1st half of next week, with
  showers and thunderstorms possible.

&&

.UPDATE...
Issued at 1110 AM EDT WED SEP 18 2024

Updated the grids just before 10am to make sure the near term
grids were on track with the current conditions. This only
resulted in some minor changes to the ongoing forecast so far.
There was also some pops included in the far northeast of the CWA
which weren`t materializing on radar, so went ahead and removed
them. Also made some minor changes to the pops over the next few
hours based on the latest CAMS, blending back into the forecast
for later this afternoon and evening as scattered pops cover a
large portion of the eastern and central CWA. This also resulted
in updates to the weather grids. All updates have been published
and sent to NDFD/web. A new set of zones and SAFs were also sent
out to remove any morning fog wording, and also update the changes
to the pop/weather in the forecast.

&&

.SHORT TERM...(Today through Thursday)
Issued at 411 AM EDT WED SEP 18 2024

Current surface analysis has the forecast area being impacted by a
weak surface low that`s been slowly riding up the eastern seaboard.
Low-level moisture, attributed to this system, has caused a stratus
deck to develop along and south of the Hal Rogers Parkway. Areas
north are seeing mostly clear skies. Temperatures overnight have
fallen into the low to mid-60s.

The aforementioned surface low and upper-level shortwave will
continue to impact the area today through the remainder of the
forecast period as it very slowly lifts northeastward out of the
area. Isolated to scattered showers and storms are forecast to
develop this afternoon. Forecast soundings for this afternoon
indicate that decent instability will be in place with pretty solid
PWs. However, not expecting anything in the way of severe weather as
shear is largely lacking across the area. High temperatures are
expected to climb into the upper-70s to low 80s. Showers and storms
will taper off toward sunset with mostly clear skies anticipated
overnight Wednesday into Thursday.

Thursday brings another chance albeit small chance of showers and
thunderstorms; mainly for areas along and east of the Mountain
Parkway as the system, that`s been impacting the region, finally
begins to eject out of the region. Forecast soundings continue to
favor thunderstorm development but once again, the lack of shear
will prevent any storm from really gaining strength. Highs for
Thursday will climb into the low to mid-80s as surface high pressure
nudges in from the southwest.

Overall, the period will be highlighted by afternoon showers and
thunderstorms with increasing temperatures. Daytime highs will begin
to climb toward the mid-80s by Thursday with overnight lows holding
steady in the upper-50s to lower-60s.

.LONG TERM...(Friday through Wednesday)
Issued at 425 PM EDT WED SEP 18 2024

The 18/12z model suite analysis beginning Friday morning depicts
a positively-tilted ridge axis extending from an ~592 dam high
over/near Del Rio, TX northeastward across the Lower Ohio Valley
and then northward across western Quebec. At the surface, high
pressure ridging is situated just east of the upper level ridge
and extends from Labrador southward along the spine of the
Appalachians. Upstream, a mean trough dips south from Canada
across the Northern Plains/Northern Rockies. Another closed low is
crossing Southern CA as it rounds the base of the upper level
trough. Ahead of that upper- level trough, a cold front is draped
from an ~992 mb surface low over northeast Manitoba down through
Duluth, MN and Kansas City, MO and westward to near/over the OK
Panhandle.

Ahead of the cold front, west to southwesterly low-level flow will
advect unseasonably warm temperatures (17-19C @ 850 mb) across
eastern KY by Saturday and Sunday. While portions of the area,
primarily near the VA border, have received a wetting rainfall this
week, many locations further north and west remain very dry (soil
moistures remain lower than 10 to 20 percentile in many spots as
per NASA SPoRT-LIS). Given the low soil moisture values,
decreasing evapotranspiration, and fair skies, stronger sensible
heating warranted nudging daily maximum temperatures upward on
Friday through Sunday toward or slightly in excess of the NBM 75th
percentile while also nudging afternoon dew points toward the NBM
10th percentile. This yields high temperatures mainly in the mid
80s on Saturday and then a few degrees warmer for both Saturday
and Sunday when warmer locales could eclipse the 90 degree mark.
This drying pattern will also support moderate ridge-valley
temperature splits developing each night--expect lows in the mid
50s coolest valleys to mid 60s in the thermal belts.

Looking ahead to new work week, the closed low initially over CA
will eject out onto the Plains Sunday and become an open wave riding
northeastward toward the Great Lakes. This system will be
accompanied by a surface wave riding the aforementioned frontal
boundary across the Plains, Great Lakes, and on into Eastern Canada.
Ensemble clustering shows significant spread developing during this
time as members struggle to resolve additional energy of North
Pacific origin diving into the trough, which could encourage
slowing/amplification of the parent trough, while, at the same time,
another tropical system potentially forms over the Gulf of Mexico.
These factors will have significant bearing upon whether the surface
low is able to push the cold front through eastern KY by the end of
the forecast period. That, of course, will have significant sensible
implications in terms of temperatures and rain chances during the
second half of the long-term period. Given the uncertainties, the
portions of the forecast from Monday onward remain very close to the
NBM with only some minor adjustments for topography. Forecast highs
cool from the mid 80s on Monday to near normal, in the upper 70s to
near 80, on Wednesday. However, temperatures could be substantially
warmer or cooler depending upon the how the pattern evolves.
Precipitation probability, timing, and intensity are also
uncertain.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
ISSUED AT 200 PM EDT WED SEP 18 2024

A strong low pressure system located east of the state will
continue to impact the region through the next 24 hours. A
scattered to broken low CU deck is in place across all the TAF
sites, generally MVFR to low end VFR (1500 - 3500 ft). These will
persist through the rest of the day, and could also lead to some
isolated to scattered showers and a possible thunderstorm during
the rest of the afternoon hours, mainly across KJKL and KSJS.
Didn`t include any reductions to VIS or CIGs with this VCTS as the
exact set up and impacts are still unknown. Will continue to
monitor through the afternoon in case updates need to be made
based on SH and TS materializing.

Then as we head into tonight, what little wind there was today
will quickly dissipate, along with the clouds and precip
potential. Models are all continuing to suggest enough moisture
and cooling across the region to lead to fog across eastern KY,
including the TAF sites. Still expecting most sites to beginning
dropping in VIS after 6Z, reaching IFR or even LIFR status by the
wee hours of the morning. These values may need to be adjusted a
bit as the fog begins to form and we see the whites of it`s eyes,
but do plan on some widespread impacts. This fog will begin
lifting by daybreak, giving way to mostly clear skies and another
round of (this time VFR) diurnal CU during the daytime hours
tomorrow/Thursday.

&&

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

$$

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