491
FXUS63 KJKL 281142
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
742 AM EDT Sat Jun 28 2025

.KEY MESSAGES...

- Hot and humid conditions will continue into the weekend, with
  temperatures (but not the humidity) gradually moderating each
  day. Heat indices will peak in the 90s to around 100 degrees
  for Saturday through Tuesday.

- Diurnal shower and thunderstorm chances continue into the first
  half of next week.

- A potential cold front passage toward the middle of next week
  may bring at least temporary relief from the heat and humidity.

&&

.UPDATE...
Issued at 741 AM EDT SAT JUN 28 2025

Updated most grids for the next 24 hours to get latest model
guidance in there. Updated Sky grids to increase cloud cover,
especially this morning, with a fair bit of remnant clouds from
yesterday`s convection. Would imagine this cloud cover burns off
and/or scatters out over the next few hours as the morning
progresses.

UPDATE Issued at 1251 AM EDT SAT JUN 28 2025

Only a bit of diminishing light rain left near the VA border.
Won`t completely rule out a bit of redevelopment overnight, but
the POP looks low, and once the current activity is gone it`s
being held to less than 20% overnight.

UPDATE Issued at 829 PM EDT FRI JUN 27 2025

Thunderstorm development has been primarily driven by outflow
interactions early this evening, with remaining activity now
mostly in southeast KY. Even this activity should be on an
overall decline through the evening. POP and sky cover has been
updated based on latest trends/obs and model runs.

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 257 PM EDT FRI JUN 27 2025

The last day of our stretch of 90+ degree days across most of the
forecast area has arrived. Temperatures have reached the 90
degree mark today for many, especially in the deeper valleys.
These temperatures, along with widespread dew points in the low
to middle 70s, are yielding heat indices in the 95 to 105 range.
However, scattered shower and thunderstorm activity has developed
and is expanding, providing relief at some locations. The latest
surface analysis shows a muddled pressure field across the
southeastern CONUS with diurnally and topographically forced
mesoscale pressure regimes in play. To the north, a weak ~1008 mb
low is passing is passing northeast of Marquette, MI. A cold
front sweeps southward from that low through Chicago, IL and then
westward past Kansas City, MO. Aloft, the remnants of a weak
circulation are found over the Southeastern CONUS. Additionally,
there is a better-defined shortwave trough passing over the
Central Plains.

The latest SPC analysis shows a highly unstable atmosphere over
the area with between 3,5000 and 5,000 J/kg of SBCAPE, highest
near Lake Cumberland, in the presence of little shear. This
instability along with microburst composite values generally
around 3 or higher, along with 0-3 km max theta-e differences
greater 20-25 C and PWATs mostly above 1.5 inches suggest that
that any stronger, deeper storms have the potential to produce
isolated damaging microburst winds. We will continue to monitor
until the activity diminishes this evening with the loss of
daytime heating. Locally heavy rainfall leading to isolated
instance of high water or flash flooding cannot be ruled out as
well.

For tonight, convection should diminish quickly after sunset with
variable cloud cover lingering. Fog is likely to form in locations
that experience rainfall, and could become locally dense. It will
remain muggy with minimum temperatures ranging from 65 to 70F.
Looking ahead to Saturday, the more shortwave trough and surface
cold front will approach from the west, sparking another round of
showers and thunderstorms this afternoon. Similar to today, the
ingredients appear to present again for the possibility of
isolated damaging microburst winds and high water. High
temperatures mainly in the upper 80s can be expected on Saturday
afternoon. On Saturday night, look for a renewed opportunity fog
after evening convection wanes. It will again be muggy with low
temperatures forecast to range from 65 to 70F.

.LONG TERM...(Sunday through Friday)
Issued at 525 PM EDT FRI JUN 27 2025

The 27/12z 500H model suite analysis beginning Sunday morning shows
a relatively zonal west-east flow over the northern half of the
CONUS while multiple subtle relative highs/lows are in place from
Bermuda back across the southern CONUS to the Desert Southwest.
Within the westerly flow, a shortwave trough will be passing
through the Mid-Mississippi/Lower Ohio Valley along with an
associated surface cold front. Further upstream, a more
substantial but low amplitude trough extends from Saskatchewan
southwestward into the southeastern Idaho. A weak surface low
reflection is found over Lake Winnipeg while its associated cold
front sags southwestward into Nebraska and Wyoming.

The leading shortwave trough just skims the JKL area as it passes to
our north on Sunday. However, the surface cold frontal boundary
remains north of the Ohio River and eventually retreats to the
northeast as a warm front. This will leave our muggy, humid air
mass relatively unchanged. Thus, expect another day of scattered
to numerous convection on Sunday after moderate diurnal-heating
induced destabilization. The next trough will amplify and dive
southeast Monday and Monday night, finally shoving its associated
cold front southeast across the Coalfields late Monday night into
Tuesday. With the warm and muggy air mass still in place,
anticipate more showers and thunderstorms from Monday into
Tuesday, with intensity/coverage modulated by the diurnal
heating/cooling cycle. A modest increase in shear is modeled as
the cold front approaches Monday night/early Tuesday, but passage
is currently favored to occur when instability is at a minimum.
Once the front clears the area, mainly dry and slightly cooler
weather is on tap for Wednesday into Thursday as surface high
pressure noses in behind a broad trough axis to our east. (Some
guidance hints at the possibility of an isolated shower or
thunderstorm on Wednesday afternoon, but that will depend upon
how quickly the front departs.) A reinforcing cold front drops
into the area late Thursday night and early Friday.

In sensible terms, expect continued unsettled weather with periods
of showers and thunderstorms, especially during the afternoon and
evening hours, into Tuesday. Temperatures on Sunday and Monday are
forecast to reach the mid 80s to near 90F in the afternoon while
nighttime minimums range in the mid 60s to lower 70s. Behind the
first cold front, expect daily high temperatures to remain very
warm, mid 80s to near 90F, but dew points will be several
degrees lower, allowing nighttime lows to fall back into the 60s
each night from Tuesday onward. This includes the Fourth of July
holiday, which at this point looks to be mostly sunny and dry
outside of the small chance of an isolated shower or thunderstorm.
Fog is likely each night, especially in valleys; but is expected
to be least prevalent Monday night when the first cold front
pushes through.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
ISSUED AT 500 AM EDT SAT JUN 28 2025

Once heating occurs during the day today, scattered thunderstorm
development is expected again in the afternoon, with localized
sub-VFR conditions. This activity should again decline on Saturday
evening. Fog will be possible again tonight, but extent is
unclear.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...CMC
SHORT TERM...GEERTSON
LONG TERM...GEERTSON
AVIATION...Titus - WFO SGF