993
FXUS63 KJKL 151947
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
347 PM EDT Thu Aug 15 2024

.KEY MESSAGES...

- Temperatures will be quite warm this afternoon, climbing to near
  90 degrees, before cooling back down closer to normal levels
  Friday.

- Humidity, along with the possibility of showers and
  thunderstorms, will increase Friday and last into Saturday night.

- Below normal temperatures are expected Sunday through Wednesday
  behind a cold front passage late Saturday night.

- Showers and thunderstorms will remain possible Sunday and
  Monday, especially in the afternoon and early evening, with a
  drying trend for Tuesday into Wednesday.

&&

.UPDATE...
Issued at 1236 PM EDT THU AUG 15 2024

Another forecast update was just issued to increase hourly and
maximum temperatures for today. Also removed any remaining
outdated afternoon wording from the zone forecast text product.
The rest of the hourly forecast elements were freshened up with
the most recent obs from around the area.

UPDATE Issued at 1025 AM EDT THU AUG 15 2024

Just sent out a quick forecast update to remove mention of fog
from the zone forecast text product. The latest obs were used to
freshen up the hourly forecast elements such as temperatures and
dewpoints to establish new trends. There some noticeable
differences between the hourly temperature obs the forecast values
so far this morning. Will continue monitoring these trends over
the next couple of hours, and might need to issue another update
that deals with todays high temperatures. Will also update later
to remove any outdated wording from the forecast for today.

UPDATE Issued at 719 AM EDT THU AUG 15 2024

The only update needed is to increase Sky cover across the
southwestern third of the forecast area with an observed increase
in high clouds transported from the next disturbance approaching
the area later today. Models suggest after a few hours of
increased cloud cover there will be a lull in such cloud cover
toward the afternoon. The grids were updated using the latest
observations for initialization.

&&

.SHORT TERM...(Today through Friday)
Issued at 315 AM EDT THU AUG 15 2024

Upper ridge axis just upstream will cross eastern Kentucky today,
with an upper disturbance quickly on its heels pushing a warm front
northeast across the forecast area by this evening. The longwave
trough begins to move into the Mississippi River Valley and Lower
Ohio River Valley late tonight into Friday, with additional
disturbances ramping up the low-level warm, moist advection into the
region, especially after midnight, with PWs rising from near 1.5"
this evening to near 2" Friday morning. Will thus have gradually
increasing PoPs and QPF moving in from the west beginning around or
shortly after midnight tonight and increasing through the pre-dawn
and morning hours. Instability looks rather limited until Friday
afternoon, so thinking the initial push of precipitation will mostly
be in the form of showers, some producing intense yet brief
downpours. For this reason, the Probability of Thunder grids were
lowered at least one category through the 18z Friday, with
additional lesser reductions in the afternoon.

Models suggest an initial round of showers and a few storms moving
across the area during the Friday morning period, though there are
significant inconsistencies as to whether this activity arrives
before dawn or after. After this initial morning round, partial
clearing in the afternoon combined with a humid and weakly unstable
environment should promote another round of showers and
thunderstorms from the afternoon into the early evening hours.

As for the temperature forecast, expect the warmest readings of the
week as weak warm advection occurs under light southwest winds, with
highs in the upper 80s to lower 90s. Warm conditions are expected
tonight as warm moist advection increases significantly through the
night, with lows in the upper 60s to around 70 degrees. Friday`s
highs will be somewhat dependent on timing of disturbances and
associated disturbances and cloud cover, but mid-80s seem like the
most likely outcome, but with increased humidity resulting in heat
indices in the mid-90s for many locations.

.LONG TERM...(Saturday through Thursday)
Issued at 347 PM EDT THU AUG 15 2024

There is good agreement among the ensemble and deterministic
solutions for an upper low to push across the Great Lakes, with the
trough axis swinging through the Ohio Valley. This coupled with a
nearby frontal boundary will keep the weather active to begin the
period. Even so, the overall evolution in convection remains in
question, as you could begin the day at times with early morning
convection. This will certainly play a roll into how much
instability can be recovered in the afternoon hours. The EFI does
show decent signal for the climatologically significant
combination of CAPE and shear on Saturday, but when looking at
CAPE alone it was a much lesser signal. This means the shear
seems to be driving the values up more and the jet energy noted in
the various solutions is one that would support deeper layer
shear. Given the uncertainties mentioned, SPC did keep a marginal
risk going for Saturday. In terms of flooding, the concern here
would be places that can see multiple iterations of storms, so
overall threat right now is lower. Outside this expect near normal
temperatures (mid to upper 80s) Saturday depending on cloud
cover.

This trough axis will continue to swig through the area and lower
heights some as it does. This will keep the weather active through
Monday. The highest chances of rain will be Sunday when chances
of rain peak at around 50-90 percent particularly in the far
eastern parts of eastern Kentucky. By Monday, afternoon highs will
be running around 10 degrees below normal, with highs in the mid
to upper 70s in most locations.

A cold front or post frontal trough will user in much dryer air by
Tuesday. The PWATs will be running in the 25th percentile range for
this time of year at around 0.75 inches. There is good agreement on
an area of high pressure pushing into the Great Lakes providing
northerly flow at the surface and will lead a much cooler night
Tuesday into Wednesday morning. The dewpoints are expected to mix
out well under deep mixing on Tuesday and did adjust this down
given the usually too hot NBM deterministic toward the 10th
percentile. Given this lowered valleys into the upper 40s to lower
50s for overnight lows by Wednesday morning. This cooler valley
trend was also noted in the COOP MOS. We will begin to rebound
through the week to near normal for afternoon highs, with
overnight lows remaining in the low to mid 50s in most cases. The
other good news is it should be nice and dry Tuesday into Thursday
under the northerly flow and lower PWAT values.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 140 PM EDT THU AUG 15 2024

VFR conditions expected to prevail through out the TAF period. SCT
cumulus clouds have sprouted over the area this afternoon, and
will remain in place through sunset. Overnight, we will see cloud
cover gradually increasing to SCT to BKN by late tonight, as an
area of low pressure moves in from the west. Scattered rain
showers will begin to affect SYM, LOZ, and SME between 11 and 13Z
Friday and JKL and SJS between 12 and 14Z. A few thunderstorms
will also begin firing toward the end of the TAF period. Winds
should remain light and variable the rest of today and tonight,
but will shift to the south or southwest early Friday with values
of around 7kts.

&&

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

$$

UPDATE...AR
SHORT TERM...CMC
LONG TERM...DJ
AVIATION...AR