364
FXUS63 KJKL 192007
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
407 PM EDT Fri Jul 19 2024

.KEY MESSAGES...

- Showers and thunderstorms will impact the region at times
  through the middle of next week. There will be a minimum in rain
  chances into this evening, before higher probabilities set in
  over the weekend and continue into the new week.

- Continued relief from the hot temperatures of earlier in the
  month will be with us throughout the period, though humidity
  makes a comeback heading into next week.

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 350 PM EDT FRI JUL 19 2024

19Z sfc analysis shows high pressure from the north having had the
biggest influence on our weather today with slightly cooler than
normal conditions, at least partial sunshine, and drier air in
place. However, a stalled frontal boundary is lingering just to
our south and this remains a source for potential showers and
thunderstorms along our southeast borders this evening. It is also
responsible for more clouds working in from the south with time
into the night. Currently, temperatures are running in the low to
mid 80s most places while dewpoints are generally in the upper
50s to lower 60s, amid light and variable winds.

The models, and their individual ensemble suites, are still in
near excellent agreement aloft through the the short term portion
of the forecast. They all depict general troughiness through the
Great Lakes and Ohio Valley with a tendency for a local minimum in
heights to consolidate to the west over the Middle Mississippi
Valley with time. This will collect much of the mid level energy
in the pattern through the weekend with a few weaker elements
drifting over eastern Kentucky during the short term portion of
the forecast in broad, weak 5h flow. Given the small model
spread, again 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 this evening
through Saturday night.

Sensible weather features a moderation of our less humid and
somewhat cool end to the work week with moisture on the increase
along with milder nights on tap. This also means an increasing,
but only gradually into Saturday morning, threat for showers and
thunderstorms working up from the south as the front lifts back
north and becomes more active. Still see a window consisting of
much of the night for the northwest half of the area to have
thin enough clouds to allow for some radiational cooling and
limited terrain distinctions along with valley fog formation. For
Saturday night, expect more uniform temperatures amid deep layer
cloud cover and higher baseline dewpoints. Some places will see
cooler conditions on Saturday but that is mainly due to more
clouds in place and the convection around, otherwise near normal
temperatures are anticipated.

The main changes to the NBM starting point consisted of adding in
some PoPs details from the CAMs for this evening through Saturday
night. Did also tweak northwest parts of area for some minor
terrain distinctions in temperatures through the night.

.LONG TERM...(Sunday through Friday)
Issued at 407 PM EDT FRI JUL 19 2024

There is good run to run continuity, thus not much change in the
forecast. Better than usual agreement among the operational
models. There is more divergence in the solutions by the end of
the period, making it slightly less certain. Pattern aloft is
amplified, but with a slow progression of systems. A mean trough
sits over the Upper Midwest at the start of the extended and
basically remains in place until the end of the entire period when
a stronger, more progressive trough drops into the Great Lakes
Region and effectively begins to kick the mean trough further east
into the heart of the Ohio Valley. This mean trough does extend
generally south-southwest into the souther Plains. A series of
disturbances of varying strength track around the base of this
mean trough before lifting northeast across the southeastern
CONUS...and portions of the Commonwealth. At the surface, a nearly
stationary, but wavy frontal zone will provide a focus for
convection through the 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 tend to be reduced through
the period and made minor adjustments to the NBM initialization
(highs and lows) to reflect this potential.

With expected repetitive rounds of rainfall, can not rule out the
possibility of locally heavy rainfall through the period. PWATS
for this type of pattern are relatively low, generally running
below 2 inches through the period. PWATS have trended slightly
higher for Tuesday night and Wednesday, where they approach 2
inches. Freezing levels are not as impressive as they could be,
generally around 13 kft or lower. Storm motion is between 10-15
kts from Sunday through Tuesday, then increase to between 15 and
30 kts for the remainder of the period. Thus in general, storm
motion is not favorable for hydro issues unless some type of
training sets up over some portion of the area. Overall
probabilities for widespread flooding problems appear low based on
ensemble probabilistic data. Ensemble probabilistic data is quite
similar to yesterday at this time, showing a high probability of
reaching an inch or more of total rainfall throughout the entire
forecast period (Sunday through Friday) are basically around 80
percent or higher for the entire area. The probability of a total
rainfall reaching two inches is greatest along and/or south of the
Hal Rogers/Highway 80 corridor, between 60 and 80 percent. Thus
average rainfall totals for the extended period could be as high
as 1-2 inches in total, with a greater chance of reaching the 2
inches being across our southern most zones.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 145 PM EDT FRI JUL 19 2024

VFR conditions will prevail at all the TAF sites through the end
of the period. A few showers and possible storms are expected to
move out of TN and into our southern counties later this evening,
with an uptick in coverage overnight. The showers and storms
should not directly affect any of our TAF sites until nearer
towards dawn and then be around through the end of the period.
Winds will remain light and variable during the period, as well.

&&

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

$$

SHORT TERM...GREIF
LONG TERM...RAY
AVIATION...AR/GREIF