219
FXUS63 KJKL 191410 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1010 AM 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
  probabilties of rain through today, before higher probabilities
  set in over the weekend and continue into the new week.

- Continued relief from hot temperatures is expected throughout
  the period, with humidity making a comeback heading into next
  week.

&&

.UPDATE...
Issued at 1010 AM EDT FRI JUL 19 2024

14Z sfc analysis shows high pressure nudging into Kentucky from
the north which brought us a fresh air mass and allowed many
places to see low temperatures in the comfortable 50s this
morning. With the high pressure clouds are mostly clear currently
as the valley fog is dissipating. Meanwhile, amid light and
variable winds, temperatures are running in the upper 60s and
lower 70s, as dewpoints vary from the mid 50s north to the lower
60s south. Have updated the forecast mainly to add in the latest
obs and trends for the T/Td/Sky grids. These minor adjustments
have been sent to the NDFD and web servers along with a freshening
of the zones and SAFs.

UPDATE Issued at 700 AM EDT FRI JUL 19 2024

Only minor changes were made to blend this mornings obs into the
forecast.

&&

.SHORT TERM...(Today through Saturday)
Issued at 430 AM EDT FRI JUL 19 2024

The large scale flow pattern in the near term will feature a large
ridge of high pressure in place across the Great Lakes, Ohio
Valley, Tennessee Valley, and the mid and upper Mississippi
Valley. A trough of low pressure will also be in place over far
southeastern Canada, with a nearly stationary frontal boundary
stretching southward into the Mid-Atlantic region, then west
southwestward through the Tennessee Valley and then through the
southern Mississippi Valley and into eastern and southern Texas.
Further west, we will see general troughiness in place, with a
decent system taking shape over the northern Plains over the next
couple of days. The boundary to our south, combined with waves of
low pressure that will be moving along it, will be the impetus
for showers and storms across eastern Kentucky later today through
Saturday.

The latest short term models were all in good agreement that high
pressure would keep the front pushed a bit further south than
previously forecast, therefore delaying the onset of precipitation
across our area until later today. In fact, if the models are
correct, we may not see the first showers and storms moving into
our area from TN until early this evening. The latest guidance is
suggesting that our rain chances will not be ramping up in earnest
until very early Saturday morning. As low pressure strengthens and
moves through the Tennessee Valley on Saturday, the front it will
be moving along should finally make a strong northwestward push,
allowing rain to overspread the most of the area late Saturday
morning into early Saturday afternoon. After a very wet day on
Saturday, the rain should begin slowly exiting the area, as the
surface front retreats southeastward.

Steadily increasing cloud cover should keep temperatures at
comfortable levels today, with highs in the low to mid 80s still
on tap. With widespread cover expected to be in place overnight,
we should see mild lows in the low to mid 60s around the area with
little if any ridge valley temperature differences. Saturday
looks to be a bit cooler, as widespread rain and clouds act to
keep temperatures from reaching the highs we are expecting today.
Winds should be generally light and variable outside of any
thunderstorms.

.LONG TERM...(Saturday night through Thursday)
Issued at 430 AM EDT FRI JUL 19 2024

he period is expected to begin with an upper level ridge extending
from portions of the Atlantic into the southeast Gulf of Mexico and
another ridging centered over the western Conus. In between, an
upper level trough is expected to expected across the Great Lakes
region into portions of the Central Conus toward the southern
Plains. To end the weekend and into the middle of next week, upper
level ridging is expected to remain in place from the western
Atlantic into the eastern Gulf of Mexico with upper level ridging
remaining centered over the western/southwestern Conus and an upper
level trough axis in between. The axis of the upper trough may move
slightly east and nearer to the Lower OH Valley region by the end of
the period. At the surface, as the trough evolves to the west, a
warm front or leading edge of deeper moisture should lift north
across the region to end the weekend and remain north of the area
before becoming diffuse at midweek. Another frontal zone should
gradually drop into the Great Lakes from early to midweek, before
slowly nearing the OH Valley region to end the period.

In the southwest flow ahead of the trough axis, multiple hard to
time shortwave troughs should impact the region. However, the
predictability of timing of any individual shortwaves into the OH
Valley and Appalachians is too low for any confidence at this time
range. In general, pops were given a diurnal flavor through the
period, with the most likely time for the greatest coverage from mid
afternoon to early evening each day of the period. With the
anticipated moisture advection from south or southwest to north
and northeast, chances will be lowest in the north to begin the
period Saturday night and Sunday before becoming more uniform
through the period. Pops were carried during the night time periods
as well given the pattern.

Moisture will increase to begin the period across the region. South
to southwest flow between the upper ridging generally extending
from near Bermuda to the eastern Gulf of Mexico and upper level
troughing extending from eastern Canada into the upper MS
Valley/Central Conus to Southern Plains will transport moisture into
the Appalachians and OH Valley regions. Per LREF mean, PW is
forecast to initially be in the 1.2 north to 1.6 inch south range
Sat evening, before increasing to 1.3 north to 1.5 south around 0Z
Monday, the 1.6 to 1.7 inch range on Monday, 1.7 to 1.8 inches
Tuesday, and remain in the 1.7 to 1.9 range through the end of the
period. Values in the 1.7 to 1.9 inch range would be close to the
90th percentile for the timeframe. Any repeated rounds of convection
or training across an area over multiple days could eventually lead
to hydro concerns. WPC EROs for the Day 4 and Day 5 periods, Monday
and Monday night and Tuesday and Tuesday night include the region in
a marginal risk of excessive rainfall. Some concern of possible
localized issues would likely linger beyond that point through the
end of period with the trough axis remaining west of the region and
the lack of a cold frontal passage.

With the trough in place, clouds should be rather prevalent through
the period, especially during each afternoon and evening. This and
anticipated convection from time to time will lead to cooler highs
that what has been experienced for much of the month to date. In
fact, highs will be near if not a few degrees below normal for this
time of year. Normal highs outside of the highest terrain are
generally in the mid 80s. With increasing moisture at the surface
and through the column diurnal ranges will be a bit limited as well
with lows anticipated in the mid to upper 60s for most nights.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
ISSUED AT 700 AM EDT FRI JUL 19 2024

Still looks like VFR conditions will prevail at TAF sites through
the end of the period. Areas of valley fog will persist this
morning until 8 or 9 am before burning off. While the weather
should stay dry for most of the day, clouds will steadily increase
through out the day, as low pressure and a surface front move our
way. After mostly clear skies early this morning, we should see
SCT to BKN middle and high clouds streaming in from the south by
this afternoon. The first showers and storms are expected to move
out of TN and into our southern counties around 0Z this evening,
with a steady increase in coverage overnight. The showers and
storms should not impact any of our TAF sites until near the end
of the period, when JKL and SJS could have showers and a few
storms in the vicinity. Winds will remain light and variable
during the period as well.

&&

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

$$

UPDATE...GREIF
SHORT TERM...AR
LONG TERM...JP
AVIATION...AR