JKL issues Area Forecast Discussion (AFD) at Jul 24, 7:18 PM EDT502
FXUS63 KJKL 242318
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
718 PM EDT Thu Jul 24 2025
.KEY MESSAGES...
- Other than the low chance of a popup shower or thunderstorm, dry
weather is expected through Friday 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 showers and storms return area-wide for the upcoming
weekend.
&&
.UPDATE...
Issued at 650 PM EDT THU JUL 24 2025
Reduced PoPs below 15 percent for the remainder of the evening
over the northwestern part of the forecast area, and refined PoPs
a bit along the Virginia border from eastern Harlan County
northeast to far southern Pike County, where widely scattered
showers have developed in the last hour or so. This activity
should dissipate with the loss of daytime heating.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 307 PM EDT THU JUL 24 2025
Another hot and increasingly steamy late July afternoon is
unfolding over eastern Kentucky. Temperatures are in the upper 80s
to lower 90s in most locales while dew points in the upper 60s to
middle 70s make those temperatures feel more like 91-101F. Skies
feature an extensive fluffy cumulus field for most locations.
Radar/satellite imagery does show that some of those cumulus have
matured further into showers near/north of I-64, utilizing some of
the 1,500-2,000 J/kg axis of MLCAPE extending up the Ohio River
(as analyzed on the SPC Mesoanalysis page). The increase in
instability is courtesy of a tropical, high PWAT (1.5-1.9 inches)
air mass that is advecting up the Mississippi Valley and into the
Ohio Valley on a return flow along the backside of a broad surface
high over the Western Atlantic. A cold front is draped from the
Canadian Maritimes southwestward through the Great Lakes to over
the Oklahoma Panhandle. Aloft, an ~597 dam parent high resides
over Cape Hatteras, NC, with a 500hPA ridge axis extending
westward through the Tennessee Valley and then southwestward into
the southern Texas.
The ridging remains strong enough to minimize deep convection
through the short-term as it drifts southwest to near the South
Carolina/Georgia border. A cold front will sag toward the Ohio
River heading into the weekend but will stall well to our north as
it runs up against the 500hPa ridge during the early portions of
the long-term forecast period. Through this evening, expect only
isolated deep pulse convection, with initiation due to minute
mesoscale (and smaller) effects such as differential heating and
perhaps barely perceptible perturbations aloft. The most favored
areas (15-25% chance) for a little rainfall will be near/north of
I-64, as well as over the higher terrain near the
Virginia/Kentucky and Virginia/Tennessee borders. After the
convection dissipates, fog is expected to develop again in the
river valleys. With increasing moisture and weak low-level flow,
the fog is expected to be more extensive than last night east of
the Pottsville Escarpment. However, toward Lake Cumberland and the
Bluegrass, fog coverage is likely to be limited by an increasing
but modest southwesterly flow at around 15 kts@925mb. On Friday,
additional deep convection is likely to fire off near/north of the
Ohio River in advance of the cold front but dwindle to just
isolated activity over northern Kentucky. An isolated shower or
thunderstorm cannot be ruled out near/over the higher terrain of
far southeastern Kentucky as well. Friday night appears similar to
the prior night, though fog is favored to be more widespread
given lighter low-level flow area-wide.
In sensible terms, look for mostly sunny skies through sunset and
just the low-end chance of an isolated shower or thunderstorm,
primarily near/north of I-64 and also adjacent to the
Kentucky/Virginia border. Temperatures are expected to peak not
far from 90F with heat indices in the middle 90s to around 100F.
Heading into tonight, mostly clear skies will dominate outside any
fog that develops in the favored river valleys. It will be warm
and muggy with lows in the upper 60s to lower 70s. On Friday, look
for mostly sunny, hot and humid conditions once again with a
slightly better opportunity for an isolated popup shower or
thunderstorm from midday through mid-evening. Temperatures will
soar back into the lower 90s for most locations while high
humidity levels make it feel more like 95 to 105F. Mostly clear
skies with the routine valley fog are on tap for Friday night as
thermometers slip back into the lower and middle 70s.
.LONG TERM...(Saturday through Thursday)
Issued at 357 PM EDT THU JUL 24 2025
Our most dominant feature through most of the long term period will
be an upper level high which will start out in the vicinity of SC
and GA on Saturday. It is expected to shift/build westward with
time, becoming most prominent over the south central CONUS by
midweek, with ridging extending north northwestward over the
Rockies. Although we will not be directly under the high, it's
proximity will give us hot and humid conditions and very weak flow
aloft. Models also suggest that on the high's periphery, it will
not be strong enough to completely suppress convective precip
over our area. However, with weak flow aloft there would be very
little movement of any showers/thunderstorms, limiting their
coverage, with much of the coverage in our area likely due to
subsequent development along outflows of initial convection.
The counterpart to the western ridge will be a deepening of a
northeast CONUS trough as the flow buckles. This would aid a surface
cold front to move southward and make it through our area. While
both the GFS and ECMWF show this, there is not model to model or run
to run consistency on the timing. At this point, the likely fropa
timing is in the neighborhood of Wednesday or Thursday. Along with
the fropa would come an increased POP, followed by drier weather
with at least some relief from heat and humidity late week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 718 PM EDT THU JUL 24 2025
VFR conditions are generally expected to prevail through the
period at the TAF sites. Lingering widely scattered convection
along the VA border will dissipate into the mid-evening. Fog is
expected to develop again in the river valleys tonight and be more
extensive than last night. Slightly weaker low-level flow aloft,
especially over southeast Kentucky, may favor wisps of fog
impacting the LOZ, JKL, and/or SJS terminals toward morning. For
now, no visibility reductions are included at the terminals.
Winds will generally be variable under 8 kts thanks to high
pressure east of the region.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...CMC
SHORT TERM...GEERTSON
LONG TERM...HAL
AVIATION...CMC
Source:
JKL issues Area Forecast Discussion (AFD) at Jul 24, 7:18 PM EDT---------------
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