JKL issues Area Forecast Discussion (AFD) at Oct 3, 8:45 PM EDT740
FXUS63 KJKL 040045 AAA
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
845 PM EDT Thu Oct 3 2024
.KEY MESSAGES...
- Weak disturbances bring a small chance for rainfall to far
southeastern Kentucky late tonight and Friday.
- A passing cold front brings another chance of showers to the
area on Sunday evening and Sunday night.
- Temperatures run 5 to 10 degrees above normal through Sunday
before typical autumn-like readings arrive on Monday.
&&
.UPDATE...
Issued at 845 PM EDT THU OCT 3 2024
00Z sfc analysis shows weak high pressure in place over the area
which is helping to keep winds light and mainly just some high
clouds in the sky. This system will likely not be strong enough to
keep some sprinkles or a light shower away in the far southeast
tonight as a mid level impulse passes just south of the area.
Currently, temperatures are running in the upper 60s to low 70s
on the ridges with some low 60s showing up in the eastern valleys.
Meanwhile, dewpoints are generally in the low to mid 60s. Look
for a decent ridge to valley temperature split through the night
along with at least some fog in the river valleys - locally dense.
Have updated the forecast mainly to add in the latest obs and
trends for the T/Td/Sky grids. These minor adjustments have been
sent to the NDFD and web servers.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 500 PM EDT THU OCT 3 2024
Late this afternoon, the axis of an upper level ridge extended
from portions of the Caribbean northwest to the southern to
Central Appalachians and then northeast to east of Cape Cod while
another upper level ridge was centered over the Southwest Conus.
An upper level trough extended from portions of the Central to
Southern Plains across the Big Bend Region of TX into northern
portions of Mexico with some disturbances moving around the ridge
axis to the east across western parts of the Gulf of Mexico with
one nearing the mouth of the MS River at this time. Otherwise,
rather strong westerlies extended from the eastern Pacific across
southwestern Canada and the Northwest Conus into broad troughing
that extended form near Hudson Bay to the Upper MS Valley to
portions of the Plains. At the surface, a ridge of high pressure
extended from southeast of the Northeast U.S. coast to the mid
Atlantic states to the OH Valley and also portions of the
Southeast as well. Meanwhile, a cold front extended from an area
of low pressure over Canada to near Lake Huron to the southern end
of Lake MI before becoming wavy over parts of Plains and
extending to the OK and TX panhandle vicinity and then to the
Rockies and further into the western Conus.
Tonight and Friday, the axis of the upper level ridge will shift
east while an upper level trough axis will shift east and work
across the western to Central Great Lakes and into portions of
the OH Valley and Appalachians. At the same time, upper level
ridging should build east into the Southern Plains from the
Southwest Conus in the wake of the disturbance/shortwave that is
near the mouth of the MS River at present that tracks around the
departing ridging and into parts of the Southeast Conus and
southern Appalachians. Meanwhile, the cold front/frontal zone
initially extending to the Great Lakes to Central Conus will move
to the Maritimes to Northeast Conus to Central Appalachians to
mid MS Valley through Friday. For Friday night, upper level
ridging should build east into parts of the TN Valley to Southern
Appalachians to as well as the Great Lakes. Associated sfc high
pressure should build from the Northern Plains to western to
Central Great Lakes through Friday and then to Quebec to the
eastern Great Lakes to mid OH Valley on Friday night, nosing into
eastern KY as the cold front sags south of the area to end the
period.
As the upper level trough approaches from the west as well as the
cold front the disturbance moving across the southeast and nearing
the southern Appalachians will bring an increase in moisture into
the southern and southeast portions of the area. This should lead
to at a minimum low and mid level cloud cover tonight and some
guidance suggests a few showers as well into the Cumberland
Mountains area from Bell to Letcher Counties near the VA border.
The deeper moisture with PW 1.1 to 1.4 inches should linger into
the day on Friday, mainly across the south and southeast as the
shortwave trough axis nears from the west and the cold front
approaches. This should lead to some continued or renewed low and
mid level clouds during peak heating along with the potential for
showers generally east of I 75 and to the south of the Hal Rogers
Parkway/KY 80 corridors. However, some of this could occur an tier
or two of counties further north. For not have isolated to
scattered pops in the more southern areas nearer to VA as
previously described on Friday. Thunder cannot be completely
ruled out near the VA border then. However, both late tonight and
on Friday, a buffer of sprinkle chances further north was
included as these that could fall from cumulus or alto cumulus.
Otherwise, skies should gradually clear on Friday night as high
pressure noses into eastern KY and chances for showers end during
Friday evening. Some valley fog is anticipated tonight,
especially where low and mid clouds develop or move in later.
Valley fog should also be a feature again on Friday night,
especially southeast even behind the boundary as winds slacken.
Lows tonight should generally be cooler in the north where clouds
should be fewer and or arrive/develop later tonight. Lower
dewpoints there should also allow for some of the more northern
valleys near or north of the Mtn Parkway to be locally cooler
tonight nearer to the 50 degree mark or lower 50s. Highs on
Friday ahead of the boundary should again be above normal by 5 to
10 degrees on average. Northern locations should again be colder
than areas further south due to lower dewpoints and earlier
clearing. Some of the normally colder valleys could reach 49 or so
in some instances.
.LONG TERM...(Saturday through Thursday)
Issued at 500 PM EDT THU OCT 3 2024
Fair weather looks to dominate the extended forecast period, with
the exception of a cold front that traverses the area on Sunday
night. During the daytime hours this weekend, a broad upper level
ridge will be responsible for our quiet sensible weather. As it
expands northward, Eastern Kentucky will experience a weekend warm-
up. Highs will hover around 80 on Saturday, but will be closer to 85
on Sunday under sunny skies. At night, this synoptic set-up will
foster ridge-valley temperature splits and likely the formation of
early AM valley fog on Saturday and Sunday, but the pattern begins
to cycle by Sunday Night.
A well-defined, fairly deep upper level low will dig into east-
central Ontario up in Canada on Sunday Night. Its associated
longwave troughing and the corresponding surface cold front will
move into the Ohio River Valley through the overnight hours. The
timing of this frontal boundary's passage will not align with peak
daytime heating in our forecast area. Combined with a lack of any
significant moisture return, this mismatch will limit the
precipitation produced by this system. Probabilistic ensemble
guidance and forecast soundings confirm the notion that this front
will be moisture starved, although some elevated showers look
possible immediately ahead of it. The greatest chances for this will
be after sunset and in northern and eastern portions of the forecast
area, where upper level support will be marginally better. It is
possible that southwestern portions of the area such as Somerset and
Monticello receive no measureable rainfall from this system, and any
showers that do form in the NE will be gone by sunrise on Monday
morning. Fog has been reintroduced to the forecast for a brief
period on Monday morning to account for a quicker clearing trend,
but will remain limited to more sheltered valleys with a nearby
source of water, including recently wet grounds. The odds of fog
formation in this time frame look slightly higher further to the NW,
where the clearing will have happened earlier in the night.
Behind this cold front, northerly surface flow and amplified NW flow
aloft will work to advect a much cooler and drier airmass into the
area. This modified continental polar airmass and the mean troughing
across the Eastern CONUS will yield below normal temperatures, with
highs hovering around 70 degrees through much of the week. Low
temperatures will easily dip down into the 40s on Monday night and
beyond, and sheltered valleys could drop down into the upper 30s for
the first time this season next week! Confidence in these
temperatures is quite high, as the model spread box and whisker
guidance plots for Monday, Tuesday, and Wednesday are relatively
compressed. A building surface high pressure system should foster
mostly clear skies during the daytime hours, but at night, this
synoptic set up once again favors radiational valley fog formation.
As such, patchy valley fog remains in the grids through the end of
the long term period.
In short, the long term weather forecast looks quite conducive for
any outdoor fall activities, especially with the cooler temps in the
forecast for next week. Given the synoptic set up for valley fog
formation, we encourage travellers be cautious during the overnight
and early morning hours for the next week. Other than that, little
to no hazardous weather is forecast for the next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 750 PM EDT THU OCT 3 2024
All the terminals are at VFR conditions to start the period.
However, fog will develop and become locally dense, mainly in
valleys with some instances in those areas of VLIFR between 04Z
and 08Z and then linger until around 12Z before lifting and
dissipating through 14Z. This fog and pockets of low stratus is
not expected to be as widespread as this past morning and
reductions at any of the TAF sites should be of shorter duration.
VFR conditions then prevail through the area for the remainder of
the aviation forecast. Winds will be light through the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...JP
LONG TERM...MARCUS
AVIATION...JP/GREIF
Source:
JKL issues Area Forecast Discussion (AFD) at Oct 3, 8:45 PM EDT---------------
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