JKL issues Area Forecast Discussion (AFD) at Jul 23, 3:30 PM EDT
724
FXUS63 KJKL 231930
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
330 PM EDT Wed Jul 23 2025
.KEY MESSAGES...
- Other than the low chance of a popup shower or thunderstorm, dry
weather is expected through TFriday as heat builds across our
region.
- Heat indices will approach 100 degrees in many places each day
through Tuesday, and could be in excess of 100 on the warmest
days early next week.
- Scattered to numerous showers and storms return for the
weekend.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 330 PM EDT WED JUL 23 2025
Thermometers range from 85 to 90 degrees across most of the area
this afternoon under mostly sunny skies. A few light sprinkles and
an isolated shower have briefly bubbled up on radar over far
southeastern Kentucky, but for most locations there have just been
some fluffy cumulus. Heat indices range from 95 to 100F at many
locations, thanks to dew points recovering back into the lower to
middle 70s. The latest analysis shows a weak surface trough
northwest of Pine Mountain under an axis of 500 to 1,500 J/kg of
MLCAPE. The trough intrudes into a broad area of surface high
pressure which is centered off of the Mid-Atlantic/New England
coast. Looking aloft, we find a parent 500 hPa ridge/high
extending from the Western Gulf Coast northeastward across Lower
Ontario and into Quebec, though a minor weakness in the ridge is
noted over Central/Southern Appalachians.
The upper level ridge will flatten out through the short term and
morph into a closed low along the North Carolina/South Carolina
coast as the associated surface high drifts into the Atlantic.
Through early this evening, the combination of continued strong
surface heating as well as the presence of weak convergence with
the surface trough and a weak vorticity max passing through the
500 hPa weakness aloft is expected to continue sparking additional
isolated convection into early evening before instability wanes
with the loss of diurnal heating. A few passing mid and high level
clouds are anticipated tonight as moisture levels continue to
rise amidst a south/southwesterly return flow on the back side of
the slowly departing high. While fog formation is likely in the
deeper, sheltered river valleys, modest flow just above ridgetop
level favors sufficient mixing to mitigate fog formation at closer
to ridgetop elevations and in more open areas. On Thursday,
another extensive cumulus field should develop, but given the lack
of any apparent forcing mechanism and little confidence where any
isolated activity is favored to develop, PoPs in the forecast
will remain too low to mention (less than 15%) at this time.
Conditions on Thursday night appear similar to the prior night.
In sensible terms, look for a hot and increasingly humid weather
pattern to continue. An isolated shower or perhaps a thunderstorm
is possible through early this evening from Wayne to Breathitt to
Letcher counties and south, but most locations will stay dry.
Thereafter, look for a mostly clear night with temperatures
settling back into the upper 60s to lower 70s. Fog is probable in
the typically favored sheltered river valley locales. On Thursday,
mostly sunny skies return with temperatures rising back into the
lower 90s for most locations. With humidity factored in, those
temperatures are expected to feel more like 97F to 102F. A very
isolated shower or storm cannot be ruled out (10% chance) but a
vast majority of the area will just be hot and dry. Thursday night
will see temperatures settling back into the upper 60s to lower
70s while fog is favored to develop once again in the sheltered
river valleys.
.LONG TERM...(Thursday through Tuesday)
Issued at 322 PM EDT TUE JUL 22 2025
By Thursday, a strong upper level low is modeled to traverse through
Canada, with a cold front extending through the Great Lakes, back
through the Mid-West and Central Plains. Meanwhile, much of the
Southeast will remain under a 596-dm ridge of high pressure. Shower
and storm chances look isolated (15% chance or lower) in nature. Dew
points remain in the low 70s, as winds remaining light and out of
the ushering in moisture rich air.
Temperatures will likely be at their warmest on Thursday, through
the forecast period. NBM has temperatures in the low 90s Thursday
and Friday, cooling slightly over the weekend, and returning into
the low 90s to start next week 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.
The last couple of days we've compared the model 850-mb temperatures
to an event earlier this year from June 22nd-26th, where temperatures
scratched 90-91 here at the Jackson Airport. In that event, the 850-
mb temperatures were 21-22C or roughly 69-72 Fahrenheit. A good
general rule of thumb is to add about 22-24 degrees to your 850-mb
temps to get a ballpark estimate at surface temperatures. Model 850-
mb temperatures for Thursday and Friday have been fairly consistent
ranging around 18-20C or 88-92F. This of course would be assuming
warming down to the surface is maximized, which isn't always the
case. The general thinking is that most areas will be flirting
around 90F with some lower elevation valleys such as Stanton, and
the surrounding Red River Gorge area possibly seeing 92-93F.
Models were fairly split in the days prior, with the big driver of
the NBM having a warm bias, being the GFS's input into it. As we're
now in the Day 3-4 window the NBM has backed off slightly on the
extent of the heat, and can live with 90-91 across the area, with 92-
93 in the warmest, low elevation valleys. 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. Friday, the above mentioned surface
cold front tries to progress east into the area, but will struggle
too, having to break down the ridge of high pressure first. This
will lead to increased cloud cover Friday, and isolated to scattered
shower and storm chances. This could hinder temperatures some if
extensive cloud cover or storms develop in the afternoon.
The Weekend, showers and storms are looking increasingly likely
Saturday and Sunday. As the high pressure that had been over the
Southeast begins to break down a surface cold front will continue to
progress into Eastern Kentucky, from the west. Aiding things will be
some moisture being transported poleward, around the high pressure,
up through the Lower Mississippi Valley. Scattered to Numerous
showers and storms will be possible each afternoon. Temperatures
will be slightly cooler in the upper 80s. Beyond the weekend, there
looks to be a subtle but important pattern shift, where an Omega
block like pattern sets up with a troughing off the coastal west
coast, a ridge of high pressure building over the Central US, and
weak troughing in the Northeast US. This will create a scenario for
Eastern Kentucky where moisture will look to ride over the ridge and
pass through the Ohio Valley to start next week. While a strong
signal of showers or storms are not currently reflected in the
forecast, chances remain of showers and storms to start next week.
Expect similar temperatures of the upper 80s to low 90s.
&&
.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
ISSUED AT 156 PM EDT WED JUL 23 2025
VFR conditions are expected at the TAF sites through the period.
A cumulus field has developed and a few stronger updrafts may
mature into an isolated shower or thunderstorm until 00z.
Forecast coverage of any possible deep convection is southeast of
the JKL and LOZ terminals. Fog will again be possible tonight,
primarily in the deep sheltered river valleys (K1A6, KI35, etc.).
However an uptick in the low-level flow will likely keep ridgetops
and open terrain slightly mixed and mitigate the threat of fog at
our TAF terminals. Winds will generally be variable under 10 kts.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...GEERTSON
LONG TERM...GINNICK
AVIATION...GEERTSON
Source: JKL issues Area Forecast Discussion (AFD) at Jul 23, 3:30 PM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202507231930-KJKL-FXUS63-AFDJKL)
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