774
FXUS63 KJKL 290330 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1130 PM EDT Fri Jun 28 2024

.KEY MESSAGES...

- Hot and humid weather is expected Saturday, with afternoon
  highs around 90 degrees and heat indices peaking around 100
  degrees in some places.

- There is potential for thunderstorms area-wide Saturday into
  Sunday as a cold front approaches and moves through. A few
  storms on Saturday afternoon and evening could produce strong
  wind gusts, large hail, and heavy rain.

- Another short-lived break from the heat and humidity is
  expected on Monday behind the cold front, quickly followed by a
  return of sultry conditions.

- An active period of showers and thunderstorms may impact the
  Fourth of July holiday period from Wednesday through Friday of
  next week. Best chances for showers and thunderstorms as of now
  are expected Thursday July 4th during the afternoon and evening.
  Heat indices will return to near 100 degrees for some locations
  as well during this time period.

&&

.UPDATE...
Issued at 1130 PM EDT FRI JUN 28 2024

No significant changes to the forecast with mainly just the
inclusion of the latest obs and trends for the T/Td/Sky grids with
this update. Did also tweak the hourly and low temps into dawn for
a small ridge to valley difference. These minor adjustments have
been sent to the NDFD and web servers along with a freshening of
the zones and SAFs.

UPDATE Issued at 850 PM EDT FRI JUN 28 2024

00Z sfc analysis shows high pressure off to the east of Kentucky
as low pressure and a cold front is approaching the area from the
west. Between these systems, southerly winds of 5 to 10 mph have
brought in very warm and moist air. As a result, temperatures
topped out in in the upper 80s and lower 90s most places with heat
indices approaching 100 degrees in many locations. Currently,
readings have started to fall back into a range from the upper
70s to middle 80s. Meanwhile, dewpoints have risen into the upper
60s and lower 70s. Still a stray shower or two are located in the
far east but that should be the last of them tonight as they fade
out over the next hour. Have updated the forecast mainly to fine
tune the limited PoPs through the night and also to tweak the
river valley fog into dawn Saturday. These minor adjustments have
been sent to the NDFD and web servers along with the forthcoming
freshening of the zones, HWO, and SAFS.

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 320 PM EDT FRI JUN 28 2024

Eastern Kentucky will reside between a west-east ridge gradually
strengthening with time across the Deep South, and fast westerly
flow moving across the Upper Midwest and Great Lakes into the
northern Mid-Atlantic region. Upper-level heights will be building
with time into Saturday evening, then begin to fall a bit more
abruptly Saturday night as an upper disturbance moves toward the
region.

Warm and moist air continues to advect north into the region with
low-level flow becoming more southerly, with dew points generally
rising about 10 degrees over the last 6 hours ending at 2 PM this
afternoon. With the moisture advection there has been scattered to
broken cumulus development across the area, but this activity is
struggling to punch through a warmer, stable pocket of air aloft.
Overnight models last night suggested some weakening of the cap late
this afternoon through mid-evening, especially as low-level winds
increase toward dark, but 12z models somewhat backed off of this
idea. Nevertheless, while the afternoon package backs off PoPs
somewhat there is an the possibility of an isolated shower or
thunderstorm late this afternoon into the evening.

The bigger story tonight will be poor temperature recovery as lows
are likely to remain well into the 70s as warm advection
strengthens. The European model Extreme Forecast Index (EFI) depicts
lows on the high-end of the climatological range. Have also adjusted
Sky cover upwards toward the CONShort model rather than the NBM
given the warm moist advection into the region. Even the typically
cooler sheltered valleys are likely to remain on the upper end of
climatology, with only a few locations likely to drop into the 60s.

Shower and thunderstorms increase through the day Saturday as an
upper disturbance moves east across the Ohio Valley through the
afternoon. Drier mid-level air will likely get advected over the
humid lower atmosphere, which should allow convection to initiate
despite subtle upper-level height rises. The NBM suggests high-end
chance to likely PoPs (50 to 60) for the afternoon and these seem
reasonable extending into the evening and overnight with some
reduction in PoPs to 30 to 40 percent in the western and
northwestern parts of the forecast area after midnight. With dew
points remaining well into the 70s ahead of a cold front, expect
another night of warm temperatures and high humidity.

Increasing winds aloft associated with the passing disturbances
aloft Saturday into Saturday night will provide sufficient shear to
support a marginal severe weather risk, with damaging winds the
primary threat and large hail a lesser threat. The greatest severe
risk is toward Interstate 64 and points north, though severe weather
can not be completely ruled out anywhere. Additionally, with PWs on
the upper end of climatology, torrential downpours with storms will
be possible. Any training of storms would increase the likelihood of
flash flooding, with this threat also falling into the category
of Marginal by the Weather Prediction Center.

Lastly, the combination of oppressive humidity and high temperatures
near 90 degrees Saturday will mean heat indices approaching or
perhaps slightly exceeding 100 degrees during the afternoon. Note
that while the criteria for a Heat Advisory is fairly widespread
coverage of heat indices at or above 105 degrees, the heat will
still have impacts on more vulnerable populations, such as young
children, the elderly, livestock, and pets.

.LONG TERM...(Sunday through Friday)
Issued at 330 PM EDT FRI JUN 28 2024

The period starts Sunday morning with a cold front passing through
the CWA. This will keep likely pops across the eastern CWA,
increasing in magnitude a bit during the afternoon with peak
heating. The front will finally shift off to the east Sunday
evening, bringing a quick end to any ongoing precip. While temps on
Sunday are forecast to be in the upper 80s, post frontal
temperatures on Monday will be between 5 and 10 degrees cooler,
with highs in the upper 70s and low 80s.

A strong area of high pressure will take hold during the day Monday
for much of the Ohio Valley and Great Lakes regions. This will
persist into Tuesday, with dry weather on tap. However, with strong
subsidence in place, mostly clear skies, and strong radiational
heating, temps will quickly react. While temperatures on Monday will
be quite cool after the cold front, temperatures by Tuesday will
moderate back into the upper 80s and low 90s.

This will set the stage for Wednesday, heading into the Independence
Day celebrations, as another day of warming is in the books amidst a
strong ridge across the region. However, despite a strong upper
level high directly overhead, a cold front will be approaching from
the NW, and the surge of llvl S to SW flow will help increase
moisture (in addition to temperatures). All models show afternoon
convection developing across portions of the state Wednesday. Highs
will top out in the low 90s, but the added moisture will increase
humidity, making it feel around 100 degrees in many locations. While
the pops may back off some Wednesday night with the loss of daytime
heating, the cold front will continue to approach, increasing pops
once more during the day Thursday as the front lays itself out
across the state. Despite the increased clouds and likely pops, the
strong WAA into the region will still be one of the main stories,
with highs topping out in the upper 80s, but heat indices in the
upper 90s - some 10 degrees higher in some locations.

By Friday, it`s a bit unclear at this point if the front will
dissipate or if it will settle south of the state. However, the
models show more zonal WSW flow across the region during the day,
with continued high pressure off to our south. Afternoon pop up
convection is forecast in nearly all the models, as is the continued
heating - despite being in a post-frontal environment. If the
current forecasts hold, temperatures on Friday will rise slightly
instead of cooling, with highs in the upper 90s and low 90s and heat
indices in the mid 90s to around 100 once more.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 815 PM EDT FRI JUN 28 2024

VFR conditions will generally prevail through the TAF period.
There is a chance of showers and a slight chance of thunderstorms
on Saturday, but there is not enough confidence in
timing/placement to include it in TAFs beyond an period of VCTS
and CBs. River valley fog is expected again late tonight, but
these will not affect the TAF sites. Generally, light south to
southwest winds will hold through the period - away from any
thunderstorms.

&&

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

$$

UPDATE...GREIF
SHORT TERM...CMC
LONG TERM...JMW
AVIATION...CMC/GREIF