JKL issues Area Forecast Discussion (AFD) at Jul 22, 3:11 PM EDT083
FXUS63 KJKL 221911
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
311 PM EDT Tue Jul 22 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
from Wednesday onward.
&&
.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...(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 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 214 PM EDT TUE JUL 22 2025
Mainly VFR condition are expected through the TAF period. A high
MVFR/low VFR cumulus field, possibly with a few embedded sprinkles
or showers, will linger through the afternoon, however any
impacts at the TAF sites should be negligible. Fog will be
possible again tonight, especially in the river valleys, but
confidence in occurrence elsewhere was too low for mention in TAFs.
If fog impacts were to occur at a TAF terminal they would be most
favored at SME or LOZ. Winds will remain under 10 knots through
the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...GEERTSON
LONG TERM...GINNICK
AVIATION...GEERTSON
Source:
JKL issues Area Forecast Discussion (AFD) at Jul 22, 3:11 PM EDT---------------
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