JKL issues Area Forecast Discussion (AFD) at Sep 27, 4:36 AM EDT525
FXUS63 KJKL 270836
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
436 AM EDT Sun Sep 27 2026
.KEY MESSAGES...
- High pressure brings dry and cool early autumn weather to begin
the week.
- Warmer temperatures return from the middle to end of next week,
along with our next reasonable potential for rain.
&&
.UPDATE...
Issued at 1202 AM EDT SUN SEP 27 2026
Valley fog is seen on satellite imagery developing in eastern
valleys as expected. The forecast is on track an no substantive
changes were necessary.
UPDATE Issued at 711 PM EDT SAT SEP 26 2026
Adjustments were made for the usual quick drop in eastern valley
temps as sunset approaches, but little in the way of change was
made to the overnight lows. Otherwise, the forecast was on track.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 257 PM EDT SAT SEP 26 2026
This afternoon, a deep and vertically stacked low is located off
the Mid-Atlantic coast; meanwhile, to the west, a high amplitude
midlevel ridge is centered roughly over the Mississippi Valley. At
the surface, high pressure is located over the Great Lakes and
Ontario. Flow around this high is maintaining light north
northeasterly winds across eastern Kentucky, which will work to
keep weather seasonable and dry for the entirety of the forecast
period. Satellite imagery does show some midlevel cloud cover
inching towards our southwestern counties, associated with some
modest midlevel PVA around the periphery of the ridge, although
this energy will only graze the forecast area at best. Otherwise,
skies are expected to be clear; model soundings show a bone dry
environment, with mostly northerly flow throughout the entire
atmospheric column, including extremely dry dewpoints just above
the surface (generally in the -20C range at 850 mb), which should
impede any cloud development. At the surface, NBM dewpoints, which
were already overdone yesterday, were nudged down significantly
to account for this dry air mixing down, and high temperatures
were accordingly nudged up a few degrees as well. Temperatures
should top out in the low to mid 70s this afternoon, with just a
passing high cloud or two outside of our southwestern most
counties.
Overnight, conditions look mostly ideal for a ridge-valley split,
with weak winds and mostly clear skies. MOS guidance is quite
aggressive with lows tonight (suggesting some sites could cool
into the 30s); however, some deterministic guidance depicts very
modest CAA continuing on ridges overnight, which could prevent
valley lows from dipping as low as MOS suggests. Further
complicating the minT forecast, ensemble guidance shows a signal
for potential stratus building in late, which could also work to
limit cooling. With such a dry air mass in place, uncertainty in
this outcome was too high to include these clouds in sky grids for
now, with just typical valley fog expected. Even so, a more
modest ridge-valley split was favored, with valley temperatures
falling into only the low to mid 40s. Any fog should dissipate
shortly after sunrise.
With a stagnant blocking pattern in place, Sunday's weather looks
to be more of the same, with sunny seasonable weather, light
mostly northerly winds, and dewpoints in the 40s, again nudged
down from the overly moist NBM. Overnight, lows look to trend a
degree or two warmer. A weak pressure gradient and mostly clear
skies will favor the development of another ridge-valley split.
Lows will fall into the low to mid 40s in valley locations, with
the most impactful weather again being typical valley fog
formation.
.LONG TERM...(Monday night through Saturday)
Issued at 425 AM EDT SUN SEP 27 2026
The start of this period will be a continuation of the pleasant
weather occurring in the near term, thanks to the approaching
upper ridge from the west and sfc high pressure ridge that
gradually shifts east of area into midweek. This pattern will keep
us dry for the first half of the week and introduce a warming
trend starting Monday, with highs increasing a bit each day. Highs
will get back into the 80s by Tuesday or Wednesday, initially in
the more southern locations. There is some model discrepancy in
what temps will be like for the second half of the week due to an
approaching trough from the west. Right now it appears most
likely that we will remain in the 80s each day and maybe even
close to 90 in some areas if the Euro is correct. Lows should also
moderate throughout the week, though the pattern favors
ridge/valley temperature splits through at least Tuesday night.
The biggest uncertainty in this period is our rain chances and
timing of the best chances during the second half of the week and
into the weekend. Model guidance and NBM accordingly over the
past couple days keeps pushing back the onset of 15 percent or
greater PoPs from Wednesday to Thursday or Thursday and now
trending toward Friday. This uncertainty originates from model
variability in the evolution of the upper level pattern which will
drive rain chances. The consensus of guidance is for the ridge
axis initially west of the area at the start of the period
migrate across the Commonwealth and then off to the east during
the second half of the week as a trough also translates from the
west coast to the central US. The trough looks to slow down or
even stall as it gets into the Central US as a ridge centered
near or east of the southeast U.S. coast and extending into the
southeast sets up. It looks like one or more subtle shortwaves
will peel off the heart of the trough in the central US and ride
the edge of that southeast ridge. The trend in the delay of PoPs
returning to eastern KY appears due to that strong southeast
ridge. The strength and positioning of that ridge will probably
result in the greatest chances of meaningful rain remaining well
off to our north and west until Friday or the weekend. NBM and
LREF ensemble guidance shows a 50-55% chance of >.1" of rain on
Saturday and a 60-75% chance of >.1" on Sunday. These higher PoPs
for the weekend have been pretty consistent over the past couple
nights so it's something worth paying attention to. Now it's worth
mentioning that although those higher PoPs have been consistent,
the upper level pattern that will deliver the active weather has
not been as consistent in the models. This will make determining
how much rain and timing of that into the region very hard to
ascertain at this time.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
ISSUED AT 235 AM EDT SUN SEP 27 2026
Valley fog was prevalent in parts of the Kentucky, Cumberland, and
Big Sandy basins to begin the period. During the next 3 to 6 hours
it should expand in coverage and intensity and is expected to be
most prevalent in the Big Sandy Basin, Kentucky mainstem and forks
as well as near the Cumberland River and Lake Cumberland and
Laurel River Lake. This will bring some instances of IFR to VLIFR.
This generally should not affect the TAF sites, though LAMP
guidance and presence of fog in the vicinity of KSJS suggest it
may be affected at times between 10Z and 13Z. A tempo group for
MVFR was added for KSJS. Other than fog in some areas through 13Z
and 14Z and possibly developing late in the period, VFR conditions
should prevail through the period. Northerly winds should remain
less than 10KT, with winds light and variable through around 14Z
and from around 00Z onward.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...HAL
SHORT TERM...FAGAN
LONG TERM...DISINGER/JP
AVIATION...JP
Source:
JKL issues Area Forecast Discussion (AFD) at Sep 27, 4:36 AM EDT---------------
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