931
FXUS63 KJKL 170205 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1005 PM EDT Fri Aug 16 2024

.KEY MESSAGES...

- Humidity, along with the possibility of showers and
  thunderstorms, will 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 1005 PM EDT FRI AUG 16 2024

Aloft, very subtle, weak short wave energy is currently passing
through the Ohio Valley. This is responsible for the isolated to
widely scattered convection that continues to fire over portions
of the area this evening. However, this activity is expected to
dissipate over the next several hours as this features continues
to pass off to our east. Another two, better defined or more
organized short wave lobes rotating around the base of Great Lakes
low pressure system will pass through eastern Kentucky over the
next 24 to 36 hours. The first appears to fire off some convection
during the day Saturday, with the second (most substantial)
impulse moving into the region very late in the afternoon or more
likely during the evening time frame. This second impulse appears
to be the upper level feature that finally drives the surface cold
front that has been residing to our northwest through eastern
Kentucky Saturday night into Sunday morning.

Main forecast challenge this evening is the potential for fog
overnight. The frontal zone appears to be close enough to our area
that a light southwest gradient wind continues through the
overnight, at least based on model guidance. The persistent
gradient wind combined with the residual cloud cover across much
of the area through the overnight will tend to help keep the
boundary layer from decoupling fully, and in turn help to mitigate
any widespread fog formation. However, ensemble probabilistic
products do suggest the potential of the development of some
stratus and light to moderate fog through the overnight. This
potential will be monitored through the remainder of the evening.

Did update grids for recent hourly trends in surface obs and the
initial incoming 0Z cycle products. Also updated the zone product
to reflect these changes and thoughts. All products have been
issued.

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 409 PM EDT FRI AUG 16 2024

The latest surface and upper air analyses reveal that a well
developed area of low pressure is in place over the western Great
Lakes, with a warm front extended southeastward from the parent low
and across the central and eastern Great Lakes into far northeast
Ohio and southwest Pennsylvania. A cold front extends southward from
the low through eastern Wisconsin and through northeastern and
central Illinois, and across central Missouri. Another area surface
low pressure is analyzed over the Oklahoma panhandle, with a surface
trough extending southwestward from there into New Mexico. High
pressure is currently dominating the southeastern CONUS, with a mix
of weak ridging and troughing in place across the western third of
the country. The cold front to the west of our area will continue to
be our primary weather maker heading into the weekend, as it moves
slowly or direction. Scattered showers and storms will continue
across our area this evening into early tonight, but should steadily
taper off overnight after we`ve lost daytime heating and
instability.

The latest model data has been all over the place with timing and
coverage of convection this evening and tonight. Based on the
uncertainty in the models, went with the best precipitation chances
very early tonight, with decreasing chance overnight. Based on the
latest data, showers and storms should be done by 7 to 9Z tonight,
with a lull in activity through Saturday morning. Showers and storms
should begin to fire back up by early Saturday afternoon, as the
cold front makes another eastward push and interacts with incoming
warm, moist air from the Gulf. Enough instability and shear may be
present Saturday afternoon and evening to produce a few strong to
severe thunderstorms across our area. The Storm Prediction Center
currently has eastern Kentucky in a slight risk, 15-20% chance, for
severe weather on Saturday, with a slight chance for damaging wind
gusts, large hail, and even isolated tornadoes all on the table.
Shower and storm activity will likely persist through Saturday and
into early Sunday morning, as a cold front and then trough of low
pressure aloft both move through the region. There is also still a
marginal, 5 to 14%, chance for excessive rainfall Saturday and
Saturday night.

.LONG TERM...(Sunday through Friday)
Issued at 356 PM EDT FRI AUG 16 2024

There remains a good amount of agreement on the overall pattern in
the various ensembles and deterministic model guidance for the long
term period. An upper level low will continue to work across the
Great Lakes and eventually into the Northeast to begin the period.
The associated trough axis will swing through the Ohio Valley and
will keep the weather active through Monday. The main cold front
will push through Sunday and this coupled with the trough axis
will keep around a 60 to 90 percent chance of rain across eastern
Kentucky. By Monday, the chance of rain decrease with most in the
50 to 80 percent range and the better forcing begins to move
eastward and PWAT values decrease in the 1.2 to 1.4 range.

Tuesday, there is good agreement on an area of surface high pressure
pushing into the Great Lakes. This will help to usher in a much
drier airmass under northerly flow at the surface. This northerly
flow will also help to provide a fall like feel to the area, with
afternoon highs in the mid to upper 70s. This surface high will
eventually pull east through the remainder of the long term
forecast. However, before it does it will provide several cool
crisp mornings, with lows in the 50s and even upper 40s in some
cases. The coldest mornings will be Wednesday and Thursday and
those days you could see valleys make it into the upper 40s. Given
this needed to adjust toward the NBM 10th percentile in the
valleys to provide better temperature splits. As mentioned, the
surface high will push east and this will eventually lead to some
return flow and highs will creep back up toward normal with low to
mid 80s being the story to end the period.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 707 PM EDT FRI AUG 16 2024

Showers and storms that plowed through the area today into early
this evening, have since exited the area and/or dissipated. Based
on quite a bit of the latest model data, only isolated activity is
expected the rest of the night. That being said, there is the
potential for a few showers and storms to fire up tonight, but not
to the point that they are worth mentioning in the TAFs. A very
challenging forecast to say the least. Showers and storms should
begin firing up again late Saturday morning into early Saturday
afternoon, as a cold front approaches, with the higher rain
chances coming toward the end of the TAF period. VFR conditions in
place currently at the TAF sites, and this may not change
overnight, but will need to be watched closely leading up to the
6Z TAF issuance later tonight.

&&

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

$$

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