688
FXUS63 KJKL 190525
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
125 AM EDT Fri Jul 19 2024

.KEY MESSAGES...

- Showers and thunderstorms will impact the region at times
  through the middle of next week. The lowest probability of rain
  occurs tonight and for much of Friday. Probabilities then
  increase as we move into the new week.

- A welcomed relief from hot temperatures is underway through the
  middle of next week. However, after a drop in humidity this
  evening and Friday, the moisture will make a comeback heading
  into next week.

&&

.UPDATE...
Issued at 1104 PM EDT THU JUL 18 2024

Only insubstantial changes were made to blend evening obs into
the forecast.

UPDATE Issued at 700 PM EDT THU JUL 18 2024

In light of late day dew points dropping to mid-upper 50s in many
northern locations, have slightly lowered tonight`s fcst min
temps in valleys in the north.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 345 PM EDT THU JUL 18 2024

19Z sfc analysis shows cooler and drier high pressure starting to
build in from the northwest in the wake of a slowly departing
cold front. With this pattern change the clouds are clearing from
northwest to southeast as that drier, and more stable, air
arrives. This is most evident in the dewpoints that currently
range from the mid 50s northwest to around 70 in the far
southeast. Meanwhile, mostly based on returning sunshine in the
wake of the front, temperatures vary from the low 80s north to the
mid and upper 70s in the southeast. At the same time, winds have
turned more northerly through this part of the state and are
running at less than 10 mph.

The models, and their individual ensemble suites, are in
excellent agreement aloft through the the short term portion of
the forecast. They all depict a seemingly persistent troughing
through the Great Lakes and Ohio Valley downstream of a nearly
perpetual dome of high heights over the Four Corners region. This
keeps eastern Kentucky in zonal, to slightly southwesterly, mid
level flow through Saturday morning. Mainly weak impulses will
track through the area aloft in this flow pattern even as local 5h
heights tick up a bit to end the work week. Given the small model
spread have gone with the NBM as the starting point for the
forecast grids with little adjustment needed aside from some
incorporation of the latest CAMs guidance for PoPs for thr latter
portion of the period.

Sensible weather features a welcomed cooler and less humid night
on account of high pressure`s semi-push into the region. This ends
by mid-day Friday, though, when the cold front to our south
starts to work back north as a warm front - guiding our next
chances of convection into this part of the state into Saturday
morning. Did allow for some terrain distinction tonight, but
mainly for just the northwest portion of the area that will have
the best shot at being mostly clear the longest. Did also include
a touch of river valley fog to account for more limited cloud
cover and radiational conditions for a good portion of the CWA
tonight and perhaps the northwest portion on Friday night.
Otherwise, shower and thunderstorm chances creep back in Friday
afternoon and will work deeper into the state from the south
through that night.

The main changes to the NBM starting point consisted of adding in
some PoPs details from the CAMs for Friday and Friday night. Did
also tweak northwest parts of area for some terrain distinctions
tonight and again for a lesser amount on Friday night.

.LONG TERM...(Saturday through Thursday)
Issued at 450 PM EDT THU JUL 18 2024

Pattern aloft is relatively amplified, and anything but
progressive across the CONUS through the extended. Wind fields are
generally quite weak across North America through the period as
well. A mean trough...low sets up over the Upper Midwest at the
start of the extended and remains in place through the entire
portion of the extended window. The trough does extend generally
south-southwest into the Ark-La-Tex. A series of disturbances of
varying strength track around the base of this mean trough before
lifting northeast across the southeastern CONUS. At the surface, a
nearly stationary frontal zone has established itself across the
southeast, oriented from southwest to northeast, roughly from
around Vicksburg, MS to Pittsburg, PA. This feature waffles north
and south a bit as weak surface waves track along it. Each passing
disturbance will tend to enhance shower and thunderstorm activity
across the Tennessee and Ohio Valleys. This frontal zone will
gradually dissipate, but the remnants appear to maintain enough
definition to keep the threat of rain in the forecast for the
entire period.

Sensible weather features a stormy extended as a series of
disturbances track through the region. Based on model solutions
and guidance, there will likely be a diurnal flavor to convection
through the period. The additional cloud cover and rainfall
associated with each passing round of convection will tend to keep
daytime temperatures down, slightly below our normal mid 80s.
Overnight lows will tend to remain up due to lingering cloud cover
and moisture. Thus diurnal ranges will not be typical and tend to
be more muted with each passing day. Did tweak temps towards a
slightly smaller diurnal range from the NBM initialization.

More interesting will be the potential for rain. Eastern Kentucky
could use some rain and this pattern may provide that much needed
rainfall. Overall probabilities for heavy rainfall are low based
on ensemble probabilistic data. PWATS for this type of pattern are
relatively low, generally running below 2 inches through the
period. Freezing levels are not that impressive either, generally
around 13 kft or lower. Shear remains low through the period as
well, less than 30 kts and for the bulk of the time well below
that. Better moisture does appear to remain further south through
the Tennessee Valley. However, with the extended time of unsettled
weather, the potential for significant amounts of precipitation
are quite high. Ensemble probabilistic data shows a high
probability of reaching an inch or more of rain throughout the
entire forecast period, basically 60 percent or higher for the
entire area...and 80 percent or higher for areas along and south
of a Berea to Campton to Paintsville line. The probability of a
total of two inches along and south of the Hal Rogers/Highway 80
corridor is between 60 and 80 percent. Thus average rainfall
totals for the extended period could be as high as an inch north
of I-64, between 1-2 inches south of I-64 but north of the Hal
Rogers Parkway, and around 2 inches south of the Hal Rogers.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 125 AM EDT FRI JUL 19 2024

VFR conditions will prevail through the end of the TAF period.
Fog is already present in valleys around the forecast area, and
will become a bit more widespread overnight, but should not cause
any issues at any of our TAF sites. Winds will be generally light
and variable through the period as well.

&&

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

$$

UPDATE...HAL
SHORT TERM...GREIF
LONG TERM...RAY
AVIATION...AR