627
FXUS63 KJKL 041955
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
355 PM EDT Fri Jul 4 2025

.KEY MESSAGES...

- The hottest temperatures of the next week are forecast this
  weekend. Although slight cooling is expected as we move into the
  new week, humidity will increase.

- Increasing humidity in the new week will be accompanied by a
  potential for showers/thunderstorms from Monday onward.

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 232 PM EDT FRI JUL 4 2025

Surface high pressure continues to exert its dominance across much
of the CONUS. This persistent pattern has maintained, and will
continue to maintain, warm and dry conditions over the forecast area.

Today, temperatures will feature highs in the low 90s, with heat
indices feeling a degree or two warmer as dew points remain in the
mid-60s. CAMs have been hinting at the possibility of very isolated
showers and thunderstorms developing this afternoon. However, any
development will struggle to sustain itself due to subsidence under
the dome of high pressure, a deep layer of dry air aloft, and
minimal vertical wind shear. If any activity does occur, it is
expected to dissipate around sunset. Overnight, anticipate lows in
the mid-60s and areas of river valley fog.

Saturday will feature largely similar weather to Friday, given the
minimal change in the synoptic pattern. Upper-level ridging and
surface high pressure will allow temperatures to climb into the low
to mid-90s, with heat indices a few degrees warmer. Similar to
Friday afternoon, isolated chances for showers and thunderstorms
will exist Saturday afternoon. However, as with Friday, the same
atmospheric factors (subsidence, dry air aloft, minimal shear) will
combine to inhibit CI and widespread convective development. Again,
any activity that does develop will dissipate toward sunset, leading
to another night of lows in the mid-60s and areas of valley fog.

In summary, surface high pressure will maintain mostly dry weather,
with high temperatures climbing into the low to mid-90s. Overnight
lows will generally remain in the mid-60s, with areas of valley fog
expected.

.LONG TERM...(Sunday through Friday)
Issued at 355 PM EDT FRI JUL 4 2025

Upper level ridging of the short term period will have largely
broken down by the start of the long term period, but the prevailing
westerlies aloft will still be to our north. This will leave us with
amorphous conditions aloft on Sunday. A series of shortwave troughs
and a weakening of subtropical high pressure off the southeast coast
will then lead to upper level troughing deepening over the eastern
CONUS through Thursday. We still will not have a substantial return
of gulf moisture early in the week, but the air mass will undergo
slow modification toward higher dew points. As geopotential heights
fall during the week and flow aloft increases, conditions will
become more favorable for mostly diurnal convection. Models show the
trough amplifying to the point that it supports a cold front
approaching KY by Thursday, which is when our highest POP arrives.

It is unclear how far the front will progress at the end of the
week, but models are suggesting it will make it to our south Friday.
Even if it passes, it is also uncertain how much change in air mass
will occur. By Friday, the front`s supporting upper trough is
expected to be weakening and lifting out to the east northeast as
another more significant trough drops southeast to the north
central CONUS. Even if there is little change in air mass, the
rising geopotential heights and weakening flow aloft would suggest
less coverage of precip for Friday. This is supported by lower
QPF values on Friday vs. Thursday in the latest runs of the ECMWF,
GFS, and GFS ensemble, and is also supported by the fastest GFS
and ECMWF MOS products. The NBM and its cron-based load into the
forecast has not picked up on this (yet), but may in subsequent
runs.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 126 PM EDT FRI JUL 4 2025

A cumulus deck has developed across the area with this TAF
issuance. This cloud deck is VFR and as a result, terminals will
be VFR. Clearing is expected overnight tonight but river valley
fog is forecast to develop which could cause category reduction
after 08Z and through 13Z. Once fog dissipates, terminals will
return to VFR. Lastly, light and variable winds are expected
through the period.

&&

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

&&

$$

SHORT TERM...VORST
LONG TERM...HAL
AVIATION...VORST