035
FXUS63 KJKL 161956
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
356 PM EDT Fri Aug 16 2024

.KEY MESSAGES...

- Humidity, along with the possibility of showers and
  thunderstorms, will increase today 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 1233 PM EDT FRI AUG 16 2024

Made some updates to the forecast for the rest of today. Based on
current radar trends and model data, precipitation probabilities
for the rest of today were overdone by quite a bit. Therefore,
decreased precip chances across the area through 23Z today per
current trends. Also lower todays hourly and max temperatures for
a large part of the area per the latest trends in surface obs. An
updated zone forecast product has been sent and any updated grids
were saved, published, and sent to the remote web servers.

UPDATE Issued at 710 AM EDT FRI AUG 16 2024

Convection has begun to increase in coverage just a bit across
the area, especially over our west central zones, and to some
extent our eastern zones. Radar is showing newly developed
convection taking aim at our Bluegrass counties as well, which
will be moving into those areas over the next hour or so. In
addition, we are seeing the second round of convection developing
upstream over central Kentucky. This upstream convection will be
expanding and moving into our forecast area a bit later this
morning. Overall the forecast appears on track at this time and
only minor adjustments were required to bring grids in line with
current hourly observations and trends in radar.

&&

.SHORT TERM...(Today through Saturday)
Issued at 450 AM EDT FRI AUG 16 2024

A slow moving mid/upper level low will move from the Upper
Midwest into the heart of the Great Lakes through the short term.
Pockets of short wave energy will round the bottom of the low as
it drifts eastward. Eastern Kentucky will reside in the left exit
region of a 40-50 kt mid-level jet today, with a 30-40 kt H850
LLJ jet nosing into the area by this afternoon. This will help
with lift across the forecast area today. However, extensive
cloud cover will tend to keep instability generally below 1000
J/kg through the bulk of the day. Shear will be marginal as well
at 25-35 kts. All said the severe threat looks marginal and as
expected SPC keeps eastern kentucky within a marginal risk for
severe weather. Consequently, the area could experience a few
strong storms and an isolated severe storm or two could not be
ruled out should any convection find itself residing within a
locally, more favorable storm environment. PWATs are reasonably
high, climbing to near 2 inches over much of the area and freezing
levels are relatively high at around 14 kft. But storm motions
are 20-25 kts or greater on average. Thus overall any hydro
threats look marginal and localized...and would more likely have
to be associated with training or repeated rounds of thunderstorms
should that occur. But even this type of scenario does not appear
particularly favorable at this time. With the expected timing of
convection and cloud debris post convection, muted afternoon
high temperatures across our east and southeast as compared to
model guidance. However, there could be some late afternoon
partial clearing and the chance for a substantial recovery of
temperatures does exist for the late afternoon time frame.

For the remainder of the short term, additional short wave energy
rotating around the upper low will pass through the Ohio Valley
tonight and then into the region again by late Saturday. Thus
after a lull in activity across eastern Kentucky through the late
this afternoon and early evening, convection may show a breif
period of enhancement late in the evening or overnight. It is
more likely that showers and thunderstorms redevelop late Saturday
with the help of late day heating as a more organized short wave
lobe tracks through the region. The surface front will be closer
to the area as well which will provide a better focus for
convection to fire. Instability and shear will be more favorable
for storms by late Saturday. However, lapse rates aloft are weak
and wind fields aloft are not as favorable for the lifting needed
for severe storms. Consequently, the severe threat will remain
marginal for late Saturday as well.

.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 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 127 PM EDT FRI AUG 16 2024

The TAFs will be challenging today and tonight, as showers and
storms continue moving through the area ahead of an approaching
surface cold front and disturbance aloft. Conditions at any give
TAF airport will vary from MVFR to LIFR due to heavy rain and fog
as showers and especially storms move through. In the meantime,
VFR should be the norm. Winds will be generally light and variable
except in thunderstorms, where winds should increase a bit and
become gusty. The rain should gradually taper off overnight, due
to loss of daytime heating. We will then see another uptick in
shower and storm activity during the day on Sunday, as moist air
continues streaming into the area ahead of the oncoming cold
front. The front should be moving through area by the end of the
day on Saturday. As before, conditions at any TAF airport could
deteriorate quickly from VFR to MVFR, IFR, or worse, in any
thunderstorm. Sky cover should be mostly BKN, but there could be a
few instances from time to time, especially north of I-64, where
we could see SCT cloud cover at times.

&&

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

$$

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