JKL issues Area Forecast Discussion (AFD) at Jul 23, 12:27 PM EDT855
FXUS63 KJKL 231627
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1227 PM EDT Wed Jul 23 2025
.KEY MESSAGES...
- Other than the low chance of a popup shower or thunderstorm, dry
weather is expected through Thursday 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.
&&
.UPDATE...
Issued at 1227 PM EDT WED JUL 23 2025
Temperatures are soaring through the 80s across all but the
highest portions of the eastern Kentucky Coalfields at midday. The
previous forecast update discussion remains on track with our
expectations through the afternoon. Satellite imagery shows a
cumulus field bubbling up, mainly south of the Mountain Parkway
so far, and becoming increasingly perturbed toward the Tennessee
and Virginia borders. Latest mesoanalysis shows a lee surface
trough northwest of and parallel to Pine Mountain and that feature will
likely be the focus for any isolated pop-up convection through
the afternoon. MLCAPE is currently analyzed at about 500 J/kg over
far southeastern Kentucky but is expected to increase to about
1,500 J/kg near the trough axis by late afternoon.
UPDATE Issued at 915 AM EDT WED JUL 23 2025
Last of the river valley fog is dissipating at mid-morning,
leaving us with a hot mid-summer day ahead. Still anticipate
widespread highs in the upper 80s to lower 90s. Humidity levels
will be ticking up a little higher through the day, and that will
push heat maximum heat indices into the 95 to 100F range for most
locales. That increasing moisture should also support a decent
cumulus field by the afternoon. CAMs continue to point to a low
end (15 to 30 PoP) popup shower or very isolated thunderstorm
threat, generally from Wayne County to Breathitt over to Letcher
and points south. Rising heights and a lot of dry air aloft are
likely to keep updraft strength weak.
UPDATE Issued at 1234 AM EDT WED JUL 23 2025
No major changes to the forecast for the early morning update.
Initialized the hourly forecast using the most recent
observations.
UPDATE Issued at 1005 PM EDT TUE JUL 22 2025
Mid-evening update is out with minor updates to Sky and
temperature grids.
Wednesday's afternoon PoPs and ProbThunder grids were also
modified after a careful examination of model soundings, with 15
percent and higher PoPs Wednesday afternoon now confined to the
Tennessee border area. Mid-level heights will be rising
steadily through the day Wednesday, with poor mid-level lapse
rates. Would thus expect a few isolated showers or sprinkles in
our southern areas, but the poor lapse rates will make any thunder
chances extremely limited and confined to the Tennessee border
area in our far southern part of the CWA.
UPDATE Issued at 725 PM EDT TUE JUL 22 2025
Lowered Sky grids compared to the previous forecast for the next
few hours. Otherwise, there are no changes to the forecast.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 311 PM EDT TUE JUL 22 2025
The mid-afternoon visible satellite imagery shows a cumulus field
south of the Mountain Parkway. Most shower activity has dropped
southeast into Tennessee and Virginia. However, a few lingering
sprinkles have been noted further north with a southward advancing
moisture boundary evident in the dew point analysis. Dew points
in southern counties are in the low to mid 70s with air
temperatures in the upper 80s to around 90 degrees. Meanwhile dew
points over the north are as low as the upper 50s/low 60s with air
temperatures in the lower 80s near I-64. The 500hPa analysis
shows a broad ridge to our west with an axis extending from near
Lake Charles, LA northward across Lake Superior and into Northern
Ontario. An ~1022 mb surface high is situated over Lower Ontario
and feeding a dry and cooler air mass down the western spine of
the Appalachians on a weak northeast breeze.
The northeasterly flow will continue to push drier air into the
eastern Kentucky Coalfields through the remainder of the
afternoon, dropping PWATs down to the 0.8 to 1.4 inch range
(northeast to southwest). The combination of dry air and some low
level moisture will favor fog formation again in valley locales,
especially over the Cumberland River Basin and in the deeper, more
sheltered valleys of the Kentucky and Big Sandy river basins. Fog
extent is less certain outside of these areas as northeasterly
flow just off the surface may be just strong enough to keep fog
from forming. As the high shifts toward Southern New England
tonight and then off of Cape Cod on Wednesday, the low-level flow
will gradually veer to southeasterly, allowing for a gradual
moisture return (PWATs climb back to between 1.3 and 1.7 inches by
late in the day). With that increase in moisture, there will also
be the return of some weak to moderate instability (500-2000 J/kg
MLCAPE in the RAP13). Weak height rises will keep mid-level lapse
rates weak and subdue updraft strength, but it is still probable
that a few showers and perhaps a thunderstorm will popup over the
higher elevations of southeastern Kentucky during the afternoon
hours. Any activity should be weak and pulsy in nature and
diminish Wednesday evening with the loss of daytime heating.
In more sensible terms, look for mostly sunny skies through
sunset with just a stray shower or sprinkle over the south. It
will be less humid, particularly over the north, with temperatures
holding near current levels until evening. Overnight, mostly
clear skies will attend temperatures dropping back into the lower
to middle 60s. Could a few of the cool northeastern hollows dip
into the upper 50s? Perhaps! Fog is favored in many of our river
valleys late in the night. Mostly sunny skies return on Wednesday
morning but are likely to be followed by extensive fluffy cumulus
and the low chance of a popup shower or thunderstorm, especially
near and south of the Hal Rogers Pkwy/KY-80 corridor. It will be
hotter with highs in the upper 80s to lower 90s. Mostly clear and
more muggy conditions follow on Wednesday night as temperatures
settle back into the mid 60s to around 70 degrees.
.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 12Z TAFS through 12Z Thursday morning)
ISSUED AT 720 AM EDT WED JUL 23 2025
Mainly VFR condition are expected through the TAF period. Fog
will again be possible tonight, especially in the river valleys.
As occurred last night and this morning, the most favored
locations for fog impacts will be at SME and/or LOZ. With little
changes in the overall pattern, persistently high dew points and a
persistence forecast, MVFR visibility conditions will be possible with
the 12z TAF package at these terminals overnight.
Winds will remain generally light and variable through the period
which may also help contribute to local areas of fog.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...GEERTSON
SHORT TERM...GEERTSON
LONG TERM...GINNICK
AVIATION...Hatch
Source:
JKL issues Area Forecast Discussion (AFD) at Jul 23, 12:27 PM EDT---------------
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