503
FXUS63 KJKL 220505 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
105 AM EDT Tue Jul 22 2025

.KEY MESSAGES...

- The current weather regime will last through the evening for
  most, with showers/thunderstorms expected at times, and
  isolated occurrences of flash flooding possible.

- The potential for rain will wane for mid week and heat is
  forecast build. Heat indices will approach 100 degrees in many
  places by late in the week.

&&

.UPDATE...
Issued at 1240 AM EDT TUE JUL 22 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.
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 750 PM EDT MON JUL 21 2025

23Z sfc analysis shows a cold front settling slowly through
eastern Kentucky. This is sustaining some training heavy showers
with the occasional lightning bolt. The slow moving nature of
these is continuing to prove a threat for isolated flooding for
that reason the Flood Watch was extended for another couple of
hours for locations along and south of the front. Otherwise,
currently temperatures are running in the upper 70s to lower 80s
most places, but lower and middle 70s with any convection.
Meanwhile, amid light and variable winds, dewpoints still elevated
in the sticky low to mid 70s. Have updated the forecast mainly to
add in the latest obs and trends for the T/Td/Sky grids and
tweaking the PoPs and QPF per the radar scans and near term CAMs
guidance. These adjustments have been sent to the NDFD and web
servers along with a freshening of the zones, SAFs, HWO, and the
FFA,

UPDATE Issued at 423 PM EDT MON JUL 21 2025

Updated POPs and Wx grids to reflect current satellite, radar and
short term model trends. No other major changes were made to the
forecast.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 304 PM EDT MON JUL 21 2025

As of 19z, a shallow surface front was situated west-to-east about
20 to 30 miles south of the Mountain Parkway and nearly bisecting
the WFO JKL CWA. The Flood Watch has been cancelled for counties
to the north of the front where convection is struggling to
sustain itself, but continues for now to the south where repeat
rounds of convection have lead to instances of heavy rain and
minor flood concerns. The area remains in a slight risk of
excessive rainfall from the WPC, through this evening.

This weak cold front that has been stalled to the north of the area
for many days will further south through much of the remainder of
the area by tonight, bringing a cooler and drier air mass to the
forecast area, particularly areas east of Interstate 75 and north of
the Hal Rogers Parkway. Meanwhile, the mid-level flow will veer from
west and west-northwesterly today to northerly tomorrow as a mid-
level ridge/high builds upstream over the middle and Lower
Mississippi River Valley.

The two main impacts to this pattern shift will be 1) cooler and
less humid conditions, moreso for eastern and northeastern Kentucky
and less so as one heads west of Interstate 75 in south-central
Kentucky; and 2) more stable and drier conditions resulting in much
lower shower and thunderstorm chances, with convection Tuesday
remaining primarily, if not entirely, south of the Mountain Parkway.

Lows tonight and Tuesday night will be much cooler than anytime in
the most recent week or two, with lower 60s for northeastern
Kentucky and upper 60s to near 70 degrees toward south-central
Kentucky. Highs Tuesday will be near normal in the mid to upper 80s,
though with lower humidity making for more bearable heat indices for
most locations.

.LONG TERM...(Wednesday through Monday)
Issued at 255 PM EDT MON JUL 21 2025

Wednesday, surface heights continue their trend higher, as high
pressure builds into much of the Southern, and Central US, including
the Appalachians. Shower and storm chances look isolated to
scattered (15-25% chance) in nature, concentrated along and south of
the Hal Roger/Kentucky 80 corridor). Dew points look to be slightly
higher than Tuesday, recovering into the low 70s, as winds become
light and out of the southeast, where Tuesday, they were out of the
northeast, leading to slightly lower dew points. With strong enough
southeasterly flow downsloping would normally be of concern, but
given how light the winds are, and the fact that its harder to
increase temperatures with higher dew points, the southeasterly
winds should be of minimal concern in regard to downslope warming.

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 595-dm high 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
Monday, with temperatures cooling into the low 70s at night. 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 valleys. This is if mixed
dry adiabatically down to the surface, fully optimizing the warming.

Models remain fairly split on temperatures for the extended period
with the GFS, National Blend, WPC, and NBM (which uses a good chunk
of the GFS in long-term), on the warmer side of solutions, in the low
to mid 90s (91-94F). ConsAll, Consshort, Euro, NAM, and SREF remain
slightly cooler with temperatures of 87-90. This is more in line
with recent trends, temperatures Wednesday through Thursday have
been blended down, populating with the a 50-50 blend of the ConsRaw
and Euro, before blending back in 25% of the NBM. This generally
drops forecasted high temperatures into the upper 80s, scratching 90-
91 in places Wednesday through Friday. Dew points remain elevated in
the 70s beyond Thursday, leading to hot and humid conditions. At
current, DESI, which previously had shown a 15-20% chance of 850-mb
temperatures meeting or exceeding 22C, now shows less than a 5%
chance. These results were achieved using the LREF Grand Ensemble.

Showers and storms may also develop towards the end of the week,
especially Friday through Sunday. This might occur as a fairly
strong upper level low moves across Canada, with a trailing cold
front extending through the Great Lakes, Ohio, and Mississippi
Valleys. Showers and storms would be situated along or near this
cold front as it passes through the area to end the week, with
better chances over the weekend. The surface high pressure that was
previously over the area mixes out downstream, however a subtropical
high begins to rebuild further west, over West Texas. For sensible
weather in Kentucky, temperatures Friday through Sunday may struggle
to reach the low 90s, with any storms that develop over the area in
the afternoon. It also means that warm weather may continue beyond
the long term period.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 105 AM EDT TUE JUL 22 2025

Expect fairly widespread valley fog development early this morning
and continuing into dawn, which will likely impact the terminals
(aside from SYM) for a good chunk of time. Then MVFR and
eventually VFR conditions return by the afternoon. Winds, will
be light and variable through the period.

&&

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

&&

$$

UPDATE...GREIF
SHORT TERM...CMC
LONG TERM...GINNICK
AVIATION...GREIF