892
FXUS63 KJKL 201124
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
724 AM EDT Sun Jul 20 2025

.KEY MESSAGES...

- The current regime will persist through early in the new week with
  showers/thunderstorms expected at times, and isolated occurrences
  of flash flooding possible.

- The potential for rain will wane at mid week and heat is
  forecast build. Heat indices should top 100 in many places by
  late week.

&&

.UPDATE...
Issued at 1245 AM EDT SUN JUL 20 2025

No significant changes were made to the forecast with mainly just
the inclusion of the latest obs and trends for the T/Td/Sky grids.
Did also touch up the fog threat through the night and limited
PoPs until closer to dawn in accordance with the latest CAMs
consensus. These minor adjustments have been sent to the NDFD and
web servers along with a freshening of the zones, HWO, and SAFs.

UPDATE Issued at 745 PM EDT SAT JUL 19 2025

23Z sfc analysis shows eastern Kentucky between high pressure to
the southeast with low pressure off to the northwest. A wavy
frontal boundary to the north of the area is keeping some semi-
organized clusters of storms and plenty of outflow boundaries
moving through the state early this evening. The strongest of
these is a cell that may yet nip parts of Wayne County while an
extensive cirrus shield is still hindering most of the strong
development on that main outflow boundary passing west to east
through the heart of the JKL CWA and on the doorstep of the
office. This activity looks to eventually wind down over the next
few hours with an uptick possible per the CAMs late tonight in the
southeast - predawn. Currently, temperatures are running in the
low to mid 80s away from any convection to the mid 70s in the
showers and storms. Meanwhile, amid light and variable winds,
dewpoints are generally in the still quite elevated low to mid
70s. Have updated the forecast mainly to add in the latest obs and
trends for the T/Td/Sky grids but also to fine tune the PoPs
through the night per the most recent radar returns and timing
along with the near term CAMs consensus. These adjustments have
been sent to the NDFD and web servers along with a freshening of
the zones and SAFs.

&&

.SHORT TERM...(This evening through Sunday night)
Issued at 355 PM EDT SAT JUL 19 2025

Isolated showers are occurring at mid afternoon, while a
mesoscale convective system is located in southern IN and
northwest KY. Models have not been handling convection well, and
there is low confidence in how things will play out. The main
development of the MCS appears to be southward into western KY,
but there has been some recent development on the southeast moving
outflow boundary near SDF. If this were to take off, it could
eventually affect our area, especially our southwest counties.
Regardless, additional scattered development is expected late
today and this evening, but coverage is in question at this point.
There is a weak mid/upper level shortwave associated with the
activity to our northwest, and it is expected to move over our
area this evening, which may eventually aid convective
development. Should activity take off, can`t rule out
training/backbuilding of cells again, but confidence in the
situation isn`t high enough at this point to warrant another watch
issuance. If convection does take off, there could be a need for
a fast issuance of a Flood Watch.

The afternoon/evening activity should mostly die out tonight.
However, some models continue to suggest additional development
overnight, fueled by modest low level inflow of warm/humid air
south of a frontal boundary sinking south through IL, IN, and OH.
An increase in POP is being carried before dawn. This boundary
sinks south to near the Ohio River on Sunday before it stalls,
and will probably aid in more development during the day as
heating/destabilization occurs. Precipitable water will remain
high (near of above 2") and deep layer flow modest and largely
unidirectional, and at least localized flooding is still a
concern. A general decrease in activity is then again forecast on
Sunday night.

.LONG TERM...(Monday through Saturday)
Issued at 342 PM EDT SAT JUL 19 2025

The beginning of the next work week has an exiting upper level
trough in the northeast, with a 594 dm ridge positioned over the
Gulf Coast. Kentucky will remain in between these regimes with a
rather stationary boundary stalled over the area through Monday.
While widespread severe weather is not expected, there is a Marginal
Risk of excessive rainfall Monday. Though, forecast soundings show
some drier air introduced into the upper levels, seemingly
mitigating the risk compared to days prior. While PWAT of 1.8-1.9 is
nothing to slouch at, Mid level RH percentages around 50% from the
Namnest shows this dry air working in.

Tuesday, heights will begin to rise across the area as high pressure
works into Kentucky. Shower and storm chances look isolated to
scattered in nature, concentrated across the south (Cumberland
Plateau and areas along and south of the Hal Roger/Kentucky 80
corridor). Dew points look to be lower than previous days, in the
upper 60s to low 70s, as winds become light and variable, mainly out
of the northeast, where previous days they were out of the
southwest, leading to higher dew points and greater storm potential.

Beyond Tuesday, the 500-mb Cluster Mean Analysis shows good
agreement of higher height anomalies over the Great Lakes, and Ohio
Valley over the remainder of the week. This is consistent with a
overall warming trend Wednesday through Saturday. By Thursday, an
upper level trough moves through Southern Canada pushing the above
normal height anomalies deeper south into the Ohio and Tennessee
Valleys, all while the modeled 594-dm high strengthens to a 598-dm
high and moves over the EKY/WV area. It is in this period where
temperatures will be at their highest. NBM has temperatures in the
low 90s Wednesday through Saturday, with temperatures cooling into
the low 70s. Heat indices are currently forecasted to reach the
upper 90s to low 100s in many areas over by the end of the week,
with some areas around or near 105, though there has been a noted
trend downward.

Back in June of this year there was a 4 day stretch from the 22nd to
the 26th where similar temperatures occurred. During those days,
observed 850-mb temperatures were 21-22 Celsius (69-72 Fahrenheit),
which roughly translated down to surface of 32-33 Celsius or 90-92
Fahrenheit. Current model runs such as the Euro suggest 850-mb
temps may be slightly cooler (19-20C). This may roughly translate
down to a surface temperature of 89-91 in the valleys. This is if
mixed dry adiabatically down to the surface, fully optimizing the
warming. There are also showers and storms that may develop later in
the week, with the previously mentioned Canadian trough, producing a
trailing cold front across the Great Lakes and Ohio Valley. This may
also hinder or work against achieving temperatures in the 90s. Dew
points remain elevated in the 70s beyond Thursday, leading to hot
and humid conditions. At current, DESI is showing a 15-20% chance of
850-mb temperatures meeting or exceeding 22C, using the LREF Grand
Ensemble.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
ISSUED AT 724 AM EDT SUN JUL 20 2025

Scattered showers and a few thunderstorms have developed across
eastern KY this morning. Brief IFR or lower flight categories will
be possible at the beginning of the forecast period under any of
this activity.

Otherwise, additional showers and storms will be possible through
the afternoon and evening hours, likely becoming the most
widespread after 18Z. The strongest storms will be capable of
heavy downpours reducing visibilities below 1 SM and gusty winds.

There will be the potential for overnight/early morning fog toward
the end of the forecast period; however, the location and
longevity of today`s convection will likely impact the extent of
the fog development, so confidence was too low to include in the
current TAFs.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Flood Watch from 1 PM EDT this afternoon through Monday evening
for KYZ044-050>052-058>060-068-069-079-080-084>088-104-106>120.


&&

$$

UPDATE...GREIF
SHORT TERM...HAL
LONG TERM...GINNICK
AVIATION...DIDIO