JKL issues Area Forecast Discussion (AFD) at Dec 8, 6:55 AM EST369
FXUS63 KJKL 081155
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
655 AM EST Sun Dec 8 2024
.KEY MESSAGES...
- After a chilly start for some, temperatures quickly warm to
above normal readings today and Monday, along with breezy
southwest winds.
- Periods of rainfall expected to lead to a widespread 0.75 to
1.50 inches of rainfall from tonight through Wednesday morning.
&&
.UPDATE...
Issued at 640 AM EST SUN DEC 8 2024
No significant changes to the forecast with just the inclusion of
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...(Today through Monday)
Issued at 450 AM EST SUN DEC 8 2024
09Z sfc analysis shows high pressure has settled well south of the
state with a low pressure system pushing toward the area from the
west. This has set up excellent conditions for a large ridge to
valley temperature split as radiation cooling in the valleys
battle an increasing southwesterly wind flow on the hills. The
winds will eventually win out but not before a few more sheltered
spots were able to settle into the lower 20s - most having since
rebounded closer to 30 degrees. Meanwhile, the ridges have stayed
up for the night and are currently sitting at a relatively balmy
mid 40s. Meanwhile, dewpoints remain generally uniform in the low
20s across the area. Winds are running at 5 to 10 mph for the low
lands with gusts up to 20 mph, but are gusting to over 30 mph at
elevations above 2000 feet - all from the southwest. On satellite,
a band of high clouds are noted over the northern quarter of the
JKL CWA and slowly drifting southeast.
The models, and their individual ensemble suites, continue to be
in very good agreement aloft through the short term portion of
the forecast, though with some increasing spread around the
shortwave passing early Monday. They all depict an opening, but
currently closed, 5h low moving out of the Southern Plains as it
gets caught up with a quickly descending and larger northern
trough dropping through the Northern Plains today. This action
brings temporary rising heights to eastern Kentucky into the
evening but as its remnants push on through by 12Z Monday we will
see some height falls and a core of its mid level energy slip by
aloft before the pattern re-flattens by 00Z Tuesday. The still
relatively small spread among the models supported using the NBM
as the starting point for the forecast grids with the main
adjustments being to temperatures this morning for lingering
terrain details. The latest CAMs guidance was also included as the
showers move into the area later tonight and linger on Monday
behind the main/deeper moisture slug that passes late tonight.
Sensible weather features some limited chilly pockets in the
sheltered valleys this morning before breezy southwest winds
break through and mix the area effectively. These winds and
partials sunshine will lead to a milder day as readings rise into
the mid and upper 50s, for most of the area, by later afternoon.
The return of these warmer conditions will also start to moisten
up the lower air mass on that southwest low level flow and likely
result in showers being able to reach the surface by mid evening
from west to east well ahead of a developing warm front. This
slug of moisture will leave behind over a half inch of rain for
the majority of the area - but also clear out to the east into
Monday morning leaving more scattered and lighter activity behind
for the rest of the day. The relatively warm weather will continue
into Monday, as well, with any colder conditions found well off
to the northwest - behind an approaching cold front that is due
in here by mid week.
The changes to the NBM starting point consisted primarily of
adjusting temperatures per enhanced terrain distinctions early
this morning. PoPs were also adjusted for CAMs timing and
placement later this evening through Monday.
.LONG TERM...(Monday night through Saturday)
Issued at 412 AM EST SUN DEC 8 2024
Still looking at an active flow pattern in the extended portion of
the forecast across the country. According to the latest runs of the
GFS, ECMWF, GFS Ensembles, and WPC guidance, their will be general
large scale troughing will be in place across the CONUS to begin the
period Monday night. A very deep trough will be taking shape over
the central Rocky Mountains to start things off. Another vigorous
trough will be pushing through the Great Lakes and into New England,
while a shortwave will be developing over the southern Plains along
the western end of a strong surface cold front. It will be the
southern stream shortwave that influences the weather of eastern
Kentucky the most heading into the middle of the upcoming work week.
This feature will push east northeastward Monday night into Tuesday,
and will phase with the Great Lakes trough, as they both push
eastward. Widespread clouds and rain will accompany this hybrid
system. Rainfall will persist across the area through the day on
Tuesday. The rain will mix with and eventually change over to snow
Tuesday night, as colder air filters into the region. The snow will
persist through the day on Wednesday, with some light snow
accumulations possible across the area. The precipitation should
taper off and finally come to and end early Wednesday evening. After
that, another arctic air mass will overspread the area, as winds
shift to the west and northwest aloft, allowing strong cold air
advection to occur over the region. With the new air mass firmly
entrenched, we can expect temperatures to max out in the 30s
Wednesday and Thursday across the area.
The departing trough should finally be far enough to our east by the
end of the week to allow winds to shift to the south or southwest,
setting up warm air advection as the milder flow becomes
established. We should see highs rebounding into the 40s on Friday,
and the upper 40s and lower 50s on Saturday, as a warmer air mass
settles over the region. The coldest nights will have lows in the
upper teens to lower 20s. The rest of the time we will see wide
variations in nighttime lows, with some nights falling into the
upper 20s and 30s. The warmest night looks to be Monday night, with
lows in the upper 40s and lower 50s on tap at that time.
As far as weather hazards go, we are not anticipating any hazardous
weather at this time, but we will keep a close eye on the snowy
period Tuesday night and Wednesday and any potential for enough snow
accumulating on roadways to cause any slick spots, although there is
low confidence of anything like that occurring at this time.
&&
.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
ISSUED AT 655 AM EST SUN DEC 8 2024
VFR conditions are expected for the first half of the TAF period;
however, as a low pressure system approaches from the southwest,
increasing and lowering CIGS are expected with most terminals
moving into the MVFR category by 04Z. Also, LLWS will continue
this morning before ending by 15Z when surface winds increase and
the low-level jet core shifts off to the east. Sustained
southwesterly winds around 10 knots with gusts around 15 to 20
knots are expected after 14Z/Sunday for all terminals. Winds will
begin to slacken after 00Z but increasing showers chances are
expected toward 02Z starting at KSME and moving northeast through
the next few hours. Once the precipitation shield moves in IFR
conditions will be possible late tonight into Monday morning and
once again some LLWS will be possible.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...GREIF
LONG TERM...AR
AVIATION...VORST/GREIF
Source:
JKL issues Area Forecast Discussion (AFD) at Dec 8, 6:55 AM EST---------------
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