-- Discussion containing changed information from previous version are highlighted. --
845
FXUS63 KJKL 152107
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
507 PM EDT Sat Jun 15 2024

.KEY MESSAGES...

- Hot and somewhat humid weather arrives on Sunday and persists
  into the upcoming week. Afternoon heat indices may peak around
  100 at some locations Sunday through Friday.

- There is a potential for thunderstorms over the Cumberland Basin
  and near the VA border on Sunday, and area wide on Monday and
  Saturday. The greatest probability is in the afternoon and
  evening hours each day.

&&

.SHORT TERM...
-- Changed Discussion --
(This evening through Sunday night)
Issued at 507 PM EDT SAT JUN 15 2024

Northeasterly breezes have ushered in a cooler and less humid air
mass today. Temperature readings have been seasonable, ranging
from around 80 in the northern foothills of the Little Sandy and
Licking river basins up to 90F at Somerset. Meanwhile, dew points
have retreated deep into the 40s in many northern locations but
have been slow to drop from the lower to middle 60s near the
Tennessee border. Sunshine has been abundant, interspersed with
just a few shallow cumulus south of the Hal Rogers Parkway/Highway
80 corridor. The delightful weather is courtesy an ~1024 mb high
pressure centered over Lake Huron but exerting influence as far
south as the Tennessee Valley and Carolinas behind last night`s
cold front. Looking aloft, an ~589 dam high is found over over
northern Alabama and Middle Tennessee.

The upper level high will slowly drift eastward to over the
Carolinas while building to ~593 dam. The attendant surface high
also strengthens as it slides off the Mid-Atlantic/Northeast
Coast. As the high shifts east, low-level flow will veer from
northeasterly this evening to southeasterly overnight and then
southerly to south southwesterly on Sunday and Sunday night. This
will help push the boundary to our south back north as a warm
front on Sunday. Not much fanfare is expected with the boundary
other than an increase in mid/high cloud cover followed by a
marked rise in dew points back to the 60s to low 70s, highest west
of I-75. CAMs suggest that convection will fire off over the
higher terrain of Middle Tennessee within the better moisture on
Sunday afternoon and there is some indication that this activity
will tend to propagate and develop further north toward Lake
Cumberland late in the day before dissipating Sunday evening. The
outflows from this convection as well as convection over northeast
Tennessee and southwest Virginia will tend to shift northward in
the evening and may be able to trigger an isolated shower or
thunderstorm further north in eastern Kentucky; however,
confidence was too low to include mentionable PoPs at most
locations north of the Hal Rogers Parkway/ Highway 80 corridor.

The sensible weather will feature delightful weather this evening as
cooler temperatures and lower humidity will be found area-wide.
Mostly clear skies, light winds, and lower dew points will set
the stage for a cooler night with lows ranging from the upper
40s/lower 50s in the coolest northern hollows to the lower and
middle 60s in the southern valleys and on the thermal belt
ridgetops/slopes. Patchy fog is expected to develop in the
typically-prone valley locales. Sunday will feature increasing
humidity levels along with increasing amounts of cumulus as heat
and moisture arrive on light southerly flow. A few late day
showers or thunderstorms are possible (20-30% chance) near Lake
Cumberland with lesser chances over the higher terrain right along
the Kentucky/Virginia border. Otherwise, it will be mostly sunny
and hot with highs in the lower to middle 90s. The increasing
humidity will make it feel more like the middle and upper 90s. On
Sunday night, partly cloudy skies will prevail along with patchy
fog, primarily in the favored valley locales. There is a low
chance (10-20%) for a stray shower or storm during the evening
most likely near and south of the Hal Rogers Parkway/Highway 80
Corridor but a very isolated shower or thunderstorm cannot be
ruled out further north as well. Temperatures will be much milder
with lows in the mid 60s to lower 70s.

.LONG TERM...(Monday through Saturday)
Issued at 408 PM EDT SAT JUN 15 2024

Models continue in agreement for the pattern that will affect our
area during the long term period. Strong upper level high pressure
will start out centered over NC. It is expected to shift north to
near NYC at mid week, with a ridge axis extending southwest over the
central Appalachians. It then shifts back south to the vicinity of
the Carolinas and weakens late in the week.

In the lower levels, moisture will have advected back north over our
area by Monday, with humidity being noticeable. Forecast soundings
show significant instability (3-4.5K J/Kg MU CAPE in the NAM)
developing during the day. The upper level ridge/high (and its
greatest influence to produce a cap and inhibit convection) should
be centered to our southeast, and our forecast soundings don`t show
a cap. This should allow thunderstorms to freely develop. However,
flow will be weak and shear negligible. This would suggest
unorganized, strong, pulse, diurnally driven convection. Without
storm organization, chance POPs given by guidance seem reasonable.
Activity will diminish Monday evening with loss of heating.

The upper level ridge axis will be building into our area by
Tuesday and should bring enough subsidence with a mid level cap
developing to help inhibit thunderstorm development. As we move
further into the week, our low level flow will emanate out of
high pressure to our east. Without sufficient time for the air
mass to modify, and along with deep mixing, this should bring dew
points down slightly, further reducing our potential for
thunderstorms. It looks like this scenario lasts through Friday.

The potential for thunderstorms could make a comeback by Saturday.
The GFS QPF shows spotty light amounts on that day, indicative of
sparse convective precip. The ECMWF remains dry. With the upper
level ridge shown to be weakening, from a synoptic viewpoint it
would make sense for at least a small possibility of thunderstorms
to return, and a 20% POP will be used.
-- End Changed Discussion --

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 156 PM EDT SAT JUN 15 2024

VFR conditions are expected through the TAF period under mostly
clear skies. A few shallow cumulus are bubbling up this afternoon
over the higher elevations near the Virginia and Tennessee
borders but are not expected to impact the TAF sites. Some thin
high clouds are also expected tonight. A more substantial high-
base cumulus field may develop on Sunday afternoon around and
beyond the end of the TAF period. Winds will be around 5 kt today
but generally favor a northeast direction today and then east to
southeast overnight tonight.

&&

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

$$

SHORT TERM...GEERTSON
LONG TERM...HAL
AVIATION...GEERTSON/CMC