JKL issues Area Forecast Discussion (AFD) at Jul 23, 7:48 PM EDT
820
FXUS63 KJKL 232348
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
748 PM EDT Thu Jul 23 2026
.KEY MESSAGES...
- Mainly dry weather is expected into Friday, with temperatures
averaging around 5 degrees below normal.
- Unsettled weather is forecast to return this weekend, with
temperatures warming to near normal by early next week.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 428 PM EDT THU JUL 23 2026
Surface high pressure beneath a broad eastern CONUS upper trough
is passing eastward north of the Ohio River this afternoon. It is
supplying a cooler and drier air mass than we have seen for some
time, but there is a north/south moisture gradient. There is still
enough moisture to fuel showers/thunderstorms to our south over
the high terrain along the TN/NC border. With the flow on the
south side of the surface high impinging on the eastern slopes of
the Appalachians, there is an inverted trough present here on the
western slopes. There are mesoscale models which have enough
moisture making it up the eastern side of this trough for a few
showers near the KY/VA border overnight and on Friday morning,
and a slight chance has been carried in the forecast for this
possibility. Otherwise, dry wx is expected through Friday.
Moisture return well to our west is expected to result in
convection over the mid Mississippi Valley on Friday night.
Moisture should stream east southeast toward us from that area on
elevated warm air advection. Models try to generate some light
precip with this over our southwest counties toward dawn on
Saturday morning. Have held the POP off during the night time
period (through 6 AM), but did allow it by 8AM (12Z) on Saturday.
.LONG TERM...(Saturday through Thursday)
Issued at 428 PM EDT THU JUL 23 2026
The long term period will be characterized by anomalously strong
upper level ridging over the central/western CONUS, with well
defined upper level troughing dominating the East Coast. This
amplified pattern will place Kentucky in a region of northwest
flow aloft for the entirety of the long term period, allowing for
a series of shortwaves to pass through the area. Multiple rounds
of showers and storms are expected over the course of the forecast
period, although the exact timing of this activity remains
uncertain at this time, owing to increasing model spread in the
progression of these smaller impulses (especially near the end of
the period).
On Saturday, southwesterly winds will continue to advect better
moisture into our area, with dewpoints rising into the upper 60s
for much of the forecast area by Saturday evening (and perhaps
even the low 70s for our southwestern counties). Concurrently, a
stalled boundary initially located over Tennessee will begin to
lift north, finding itself near the KY/TN line by the evening
hours, with weak WAA in the low levels in our southernmost
counties. This, in addition to the potential for assisting
shortwave perturbations, will lead to a chance for scattered
showers and storms throughout the weekend, with the highest rain
chances near the KY/TN line. Shear will remain fairly weak, so any
storms that do form will not bring a risk for organized severe
weather, and will more so be typical pulse storms. However, the
air mass in place ahead of this convection will be anomalously
moist; LREF mean PW is generally in the range of 1.6-1.8 inches in
the southern portion of the forecast area, representing 75th to
85th percentile PW values when compared to climatology. Given this
juicy environment, any storm that forms would be capable of
producing efficient rainfall. Accordingly, the Weather Prediction
Center has introduced a Marginal (Level 1/4) Risk for Excessive
Rainfall for our counties closest to the TN line; this represents
a chance for isolated flash flooding should a storm be able to
capitalize on this moist environment, although the overall flash
flood risk appears quite low at this point. There is some model
disagreement regarding overnight activity going into Sunday
morning, with an additional subtle wave represented in some
models. Should this come to fruition, cloud cover would prevent
any ridge/valley temperature split from developing overnight.
However, if skies can clear out some, a modest ridge/valley
temperature split could develop, with this outcome most likely in
our northern counties that remain somewhat removed from the best
rain chances. For now, have held off on the introduction of any
ridge/valley split into the forecast grids due to cloud cover
uncertainties; however, this may need to be adjusted as the timing
of shortwave energy becomes more certain.
Rain chances decrease again on Sunday as the upper level ridge
over the Great Plains amplifies and expands slightly east.
Meanwhile, the trough to the east of the forecast area will
continue to deepen. At the surface, winds will become more
northwesterly, tapping into a very muggy upstream air mass that
will drive further moisture advection. Temperatures will also
continue to warm, with high temperatures in the upper 80s expected
across the forecast area, marking a return to hot and muggy
weather, although nearby high pressure should keep rain chances
fairly low during the day. Then, model guidance begins to diverge
significantly by Sunday night, and especially next week.
Looking ahead, a period of active weather appears to be
increasingly probable next week. Notably, the upper level pattern
will be favorable for MCS type activity, with eastern Kentucky
remaining on the eastern periphery of the highly amplified ridge
over the Plains. In fact, the 12Z GFS shows a signal for a
convective complex through the Commonwealth as early as overnight
on Sunday, although this solution remains an outlier at this time.
Any MCS type activity will remain dependent on the upstream
evolution of convection, which is subject to tremendous
uncertainty at this stage in the forecast; however, with dewpoints
in the upper 60s to low 70s and temperatures generally expected
to rise into the upper 80s and low 90s (barring convective
interference), the thermodynamic environment will be capable of
supporting severe weather. Kinematics will also noticeably improve
early next week as mid and upper level flow strengthens, with
LREF mean 0-6 km shear generally in the range of 30-40 kts on
Monday and Tuesday. Notably, machine learning guidance has picked
up on some severe potential in this time frame, with probabilities
peaking on Monday and Tuesday. The Storm Prediction Center has
introduced a Day 5 (Monday) 15% contour just north of Kentucky,
including much of Indiana and the western half of Ohio, reflecting
increasing confidence in MCS activity; however, uncertainty still
remains high, and SPC notes that the location of this outlook may
shift in coming days. Of note, the Weather Prediction Center has
also introduced a broad Day 5 (Monday) Marginal (Level 1/4) Risk
for Excessive Rainfall, including approximately the northern half
of our forecast area. However, similarly to the severe threat, any
flash flooding risk would remain highly dependent on the
progression of upstream convective activity, and significant
uncertainty exists in the forecast at this range.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 748 PM EDT THU JUL 23 2026
Fog should affect valleys in southeast KY overnight and early
Friday, bringing localized IFR or worse conditions. However, no
fog impacts are expected at the TAF sites. Any fog should burn
off/lift quickly after sunrise on Thursday. Otherwise, there will
be mid and high level clouds through the period with the thickest
cloud cover generally closer to the KY-VA border. Winds will
remain light.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...HAL
LONG TERM...FAGAN
AVIATION...GEERTSON/HAL
Source: JKL issues Area Forecast Discussion (AFD) at Jul 23, 7:48 PM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202607232348-KJKL-FXUS63-AFDJKL)
---------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!