-- Discussion containing changed information from previous version are highlighted. --
185
FXUS63 KJKL 231718
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
118 PM EDT Sun Jun 23 2024

.KEY MESSAGES...

- An approaching cold front will bring some much needed rain to
  eastern Kentucky this afternoon and night. A few storms may
  approach severe thresholds with damaging winds being the primary
  threat.

- Much appreciated cooler temperatures are on tap for Monday after
  the passage of the above-mentioned cold front, with highs in the
  mid 80s. Unfortunately, this isn`t the end of our 90 degree
  pattern, however. Tuesday and Wednesday will see the return of
  low 90s. Friday and Saturday will be the hottest 2 days of the
  forecast, with highs in the low to mid 90s.

- Another round of showers and thunderstorms is expected from
  Wednesday through Thursday, with the threat peaking during the
  day Wednesday. More showers and storms are on tap for the
  weekend as well.

&&

.UPDATE...
Issued at 1224 PM EDT SUN JUN 23 2024

The line of showers continues become less and less defined as it
tracks across eastern Kentucky, with only a few sprinkles perhaps
in most cases. We are seeing a few showers develop to the north
and west of eastern Kentucky this afternoon, but the building of
better instability this afternoon should lead to an increase in
coverage through the remainder of the afternoon into this evening.
Overall no big changes needed for this update.

UPDATE Issued at 941 AM EDT SUN JUN 23 2024

A line of rain showers pushing east toward eastern Kentucky this
morning continues to loose steam, and it is starting to break up
in spots along the line. The CAMs have this feature falling apart
as it tracks eastward and overall seems to be the case so far this
morning. More showers and thunderstorms are still expected to
develop this afternoon and evening amid moderate instability and
fairly anomalous low-level flow. The CAMs are showing this
potential, but vary in how this will evolve. This could lead to a
few strong to severe storms this afternoon, with damaging wind
gusts remaining the main threat. Overall, the forecast looks on
track at this time given the uncertainty on evolution of
convection this afternoon. Outside of this only minor edits were
made to add in the latest obs and trends.

UPDATE Issued at 706 AM EDT SUN JUN 23 2024

Line of showers and thunderstorms now extends from Cleveland, OH
to Dayton, OH to Evansville, IN to Cape Girardeau, MO and is moving
quickly to the east. Mesoanalysis indicates that the atmosphere
south of the Ohio River is quite stable. IR satellite cloud top
temperature trends already show warming, indicative of weakening
updrafts. Expect the southern portions of the line (especially
south of the Ohio River) to rapidly weaken and and eventually
dissipate to spotty light showers or sprinkles over the next few
hours as it moves into and through Kentucky. Still expect just a low
shower chance (under 30%), primarily north of I-64, as the
remnants of this line reach eastern Kentucky later this morning.

&&

.SHORT TERM...(Today through Monday)
Issued at 405 AM EDT SUN JUN 23 2024

The latest observations show yet another warm, muggy night across
eastern Kentucky with temperatures ranging from 68 in the coolest
valleys to around 77 on the warmest ridges at 8z. Some fog has
also developed in the deeper southeastern valleys. The latest
surface analysis shows eastern Kentucky situated between high
pressure over the western Atlantic and a cold front extending from
~1000 mb low pressure near/over Lake Huron southwestward through
St. Louis and then further southwest into the upper reaches of
the Red River Valley of the South. Looking aloft, the high
responsible for the hot weather of late is retrograding westward
across the Southern Plains while a sharpening shortwave trough is
passing the the Upper Great Lakes/Midwest. Upstream radar shows a
band of convection along the cold front Michigan southwestward
into Central Missouri.

This band of convection is expected to outrun the front this morning
and then dissipate over the Ohio Valley late morning and midday due
to a loss of forcing and lack of instability. For eastern Kentucky,
this line brings low chance PoPs (less than 30%) late this morning
to locations north of I-64. As long as cloud cover from this
convective debris moves out quickly, expect moderate instability
(1,000 to 2,000 J/kg) to build this afternoon ahead of the cold.
Increasing winds aloft are forecast to result in 25 to 30 knots of
EBWD. Model soundings also suggest sufficient dry air aloft for
strong downdraft and thunderstorm cold pool development. This
combination of ingredients will favor the formation of organized
multi-cluster thunderstorms ahead of the cold front late this
afternoon and evening. The primary threat appears to be isolated
to scattered damaging wind gusts, though an isolated instance of
large hail cannot be ruled out. SPC has upgraded the Marginal Risk
Severe Weather Outlook to a Slight Risk north and west of the Hal
Rogers Parkway/Highway 80 and I-75 corridors today. Further
southeast near the Virginia border, the severe risk appears lower
as thunderstorms will arrive later in the evening when
instability will be waning, thus the Marginal Risk remains in
effect there. Given the heat and dryness of late, any rainfall
should be beneficial. Showers and thunderstorms quickly move
southeast late this evening and early overnight, largely exiting
into Virginia before midnight. However a lingering stray shower
cannot be ruled out deep into the wee morning hours over northeast
Kentucky when the cold front finally drops through the area.

In sensible terms, look for any fog to burn off quickly this morning
after sunrise. A period of increased cloud cover can be expected
late morning and midday along with the the possibility of a stray
shower, particularly north of I-64. Otherwise, mostly sunny skies
will buoy temperatures into the upper 80s north and lower 90s
south before fading to increasing and deepening cloud cover.
Showers and thunderstorms are expected to increase from the
northwest late in the afternoon and early evening over the
Bluegrass and spread southeastward through the evening. Some of
these storms could be severe and produce wind damage. Rainfall
amounts could be quite variable ranging from less than 0.1 inch at
drier locales to perhaps 0.5 to 1.0 in the areas which experience
the most direct thunderstorm impacts. The thunderstorm threat
quickly fades this evening after sunset, though a small chance for
showers hangs on over northeastern Kentucky deep into the early
Monday morning hours. Skies should eventually clear, allowing
radiation fog to form at many locations. It will be cooler with
lows ranging from the lower 60s north to the upper 60s south.
Looking ahead to Monday, skies should become mostly sunny while
temperatures remain cooler, only reaching the lower to middle 80s.

.LONG TERM...(Monday night through Saturday)
Issued at 346 AM EDT SUN JUN 23 2024

The forecast starts off with one of the few dry spells of the
extended period, as an area of high pressure passes over and upper
level heights are on the rise behind the exiting trough that will
impact us today. Dry weather is expected to remain in place through
the day Tuesday. However, KY will find itself in the return flow
backside of the passing high on Tuesday, allowing WAA into the
region. This will couple with good radiational heating, allowing
temps to rise to around or just above 90 degrees again by the
afternoon.

This pattern won`t continue past Tuesday, unfortunately, as another
upper level system passes into South-Central Canada Tuesday
afternoon. This will also result in a low pressure system in the
same vicinity, reaching the western border of Quebec by 0Z
Wednesday. From this system, a cold front will extend southwestward,
with showers and thunderstorms possible along it. This will make
it`s way into the state by Tuesday night, coupling with a
strengthening shortwave which will also be traversing the state late
Tuesday night and through Wednesday. While chance pops are expected
to begin infiltrating the CWA early Wednesday morning, the increased
energy of the shortwave, combined with daytime heating, will amplify
both pops and QPF during the afternoon Wednesday. Strong SW flow
just ahead of this frontal boundary will keep temperatures in the
low 90s for most locations, despite the clouds and rain.

Pops will continue into Wednesday night, slowly diminishing to the
east as the front and upper-level shortwave slowly transition away
from the state. Unfortunately they won`t be far enough away by
Thursday to not influence some continued precip chances, mainly in
the far SE. These should be mainly upslope flow and diurnally
driven, quickly diminishing by Thursday evening. Post-frontal temps
on Thursday will be a bit cooler than Wednesday, but still warm,
with highs in the mid and upper 80s.

Once this system finally exits Friday night, another round of high
pressure to our northeast will take hold. Models show generally dry
conditions then until Saturday, though the ECMWF and consequently
the NBM do try to show some pop up convection across the far eastern
CWA during the afternoon hours Friday. The current NBM only has it
impacting a couple counties for a few hours, but didn`t have the
confidence to remove it at this point, especially with one of the
models showing it. Again, during this spurt of high pressure, winds
will become more southerly and sunshine will be abundant, so
temperatures will easily climb back into the low to mid 90s on
Friday. Humidity will make it feel several degrees warmer still.

This SW flow and heat will only increase for Saturday, as yet
another system begins to approach the region. It will be very
similar to the mid-week system, with a surface low and upper level
trough passing across southern Ontario, and a cold front stretched
southwestward across much of the US. This front and associated
precip will move into the state Saturday night and continue into
Sunday. All the models also show generally isolated pop up
convection ahead of the system during the day Saturday as well.
Highs on Saturday will easily top the mid 90s in most locations,
with heat indices even higher.

&&

.AVIATION...
-- Changed Discussion --
(For the 18Z TAFS through 18Z Monday afternoon)
ISSUED AT 118 PM EDT SUN JUN 23 2024

A line of mainly sprinkles continues to push southward across the
area this afternoon. We are mainly seeing mid- and high level
clouds as a result. However, some lower cloud bases are working
across northern Kentucky this afternoon and could lead to some
near MVFR Cigs through the afternoon and evening. The potential
also still exists for increasing chances of showers and
thunderstorms through the afternoon and evening, but still some
uncertainty on if and when these will occur at the TAF sites.
Opted to add in some rain showers/VCTS between 22Z and 23Z when it
seemed like we would see peak in the deeper moisture and moderate
instability. Outside of this, river valley fog could be a concern
later tonight and will be some what dependent on the amount of
rainfall we see from any storms that develop this afternoon. The
winds will be out of the southwest this afternoon at 5-10 knots,
with gusts of around 15 to 20 knots. These could be higher and
more erratic at TAF sites that happen to experience any
thunderstorms. However, the wind will slacken through the later
evening hours to around 5 knots or less.
-- End Changed Discussion --

&&

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

$$

UPDATE...DJ
SHORT TERM...GEERTSON
LONG TERM...JMW
AVIATION...DJ