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Emergency Information => Weather Info => Topic started by: ThreatWebInternal on December 12, 2024, 05:45:08 PM

Title: [Alert]JKL issues Area Forecast Discussion (AFD) at Dec 10, 4:45 AM EST
Post by: ThreatWebInternal on December 12, 2024, 05:45:08 PM
JKL issues Area Forecast Discussion (AFD) at Dec 10, 4:45 AM EST

148 
FXUS63 KJKL 100945
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
445 AM EST Tue Dec 10 2024

.KEY MESSAGES...
 
- Warm temperatures will last through this afternoon, with a brief
  blast of much colder air then arriving on Wednesday behind a
  couple of cold fronts.
 
- Showers will accompany a passing low pressure system today into
  tonight.

- Minor, light snow accumulations are possible from early Wednesday
  into Wednesday night.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 445 AM EST TUE DEC 10 2024

09Z sfc analysis shows the lead area of low pressure spreading
into central Kentucky from the southwest. This is pushing a warm
front north into the Cumberland Valley early this morning bringing
showers along with a stirring in the winds. This appears to be
enough to clear out the areas of low clouds and fog plaguing the
I-75 corridor region - while some radiation based fog is noted
further east along the river valleys. Look for that to clear up by
dawn, as well, as the pcpn spreads northeast through the JKL CWA.
Currently temperatures (and dewpoints) are mainly in the upper
40s and lower 50s with a few colder valley pockets in the low 40s
where the radiational cooling was effective in the cloud breaks
northeast of the arriving front. Meanwhile, winds are light to
calm most places but southeast at 5 or so mph where the front is
pushing into the area.

The models, and their individual ensemble suites, are now in
excellent good agreement aloft through the short term portion of
the forecast, despite a very dynamic and potentially impactful
pattern adjustment. They all depict a full latitude trough
bottoming out through central Texas later today as it digs toward
our region. This will mean one last day of strong southwest flow
at mid levels for the state though 5h heights will be falling
locally. In this fast flow, a weak impulse passes through this
morning and early afternoon from southwest to northeast while the
main trough sweeps its way closer. By late tonight, larger 5h
height falls spread into Kentucky from the west with a stream of
energy riding over the state. This feature will be at maximum
affect for the area Wednesday afternoon as the troughs axis
passes through eastern Kentucky with its core energy lifting
through the southern Appalachians and brushing by far southeast
Kentucky. Just as quickly as it arrives on Wednesday, it will
already be clearing out aloft by that evening allowing mid level
heights to rebound and the pattern to start flattening. The quite
small spread among the models favored using the NBM as the
starting point for the forecast grids with little adjustment
needed, aside from the incorporation of the latest CAMs guidance
through the period for PoP timing and placement.

Sensible weather features one last warm day with showers quickly
passing through by early afternoon for most places. We could even
hear a rumble of thunder or see a stray lightning bolt from the
strongest of these showers. The showers (and thunder chances)
linger in the east of the JKL CWA into the first part of the
evening before drier air behind the initial wave moves in from the
northwest. After a lull, the system's cold front will press into
the area from the west with its colder air transitioning
lingering rain to snow by dawn from west to east. There is a
potential for an uptick in pcpn through dawn from this -
especially in the far east as depicted in many of the CAMs.
Additional moisture associated with the front will bring snow
chances west to east across the CWA from 10 to 14Z Wednesday.
Generally, just a dusting of snow is expected from this, but up to
an inch could occur - mainly over the southeast higher terrain
into Wednesday morning. Impacts should be minimal, though given
the antecedent warmth and well above freezing road surfaces
through the day, Wednesday. Cannot rule out some slick spots
where any of the snow showers come down briefly at moderate rates
- again mainly in the higher terrain of the far east. For most of
the day insolation will hold off the CAA attempting to drop
temperatures back below freezing, but after dark that changes just
as secondary, and reinforcing, cold front arrives from west to
east with another bout of snow showers possible and a greater
potential to stick to the roads. Low QPF will limit any
accumulations from this second shot at snow from the system, but
the CAMs do suggest that a few of the snow showers could be
intense with brisk winds gusting to between 20 and 25 mph helping
to reduce visibility within any snow shower Wednesday evening.
This will be monitored for any possible headlines or SPS issuances
highlighting the winter impact concerns.

The changes to the NBM starting point again consisted primarily
of adjusting PoPs per the latest CAMs timing and placement through
Wednesday.

.LONG TERM...(Wednesday night through Monday)
Issued at 415 AM EST TUE DEC 10 2024

The extended portion of the forecast will start off quite active, as
a large and powerful low pressure system churns across the eastern
fourth of the nation Wednesday night and Thursday. Scattered snow
showers will be exiting the area Wednesday evening, as the trough
moves quickly off to the east of our area. Very cold air will
continue to spill into the region, as westerly flow persists behind
the departed storm system and cold high pressure settles over the
area. This ridging will remain in place to finish out the week,
leading to dry and warming weather for eastern Kentucky. According
to the latest runs of the GFS, ECMWF, and WPC model guidance,
another trough of low pressure will be moving our way heading into
the weekend. This system will be fast moving, and will bring quick
round of rain to the area over the weekend. After this system
departs the region late Sunday, the latest guidance has yet another
storm system moving in to begin the new work week. This low pressure
system will bring another bout of rain to eastern Kentucky to end
the period. The good news is, the passage of these last two storm
systems will lead to primarily southerly flow across our area, which
will allow temperatures to warm up nicely over the weekend and into
the first of next week. Highs each day from Friday onward should
average out in the upper 40s to mid 50s. We are not anticipating any
weather hazards for eastern Kentucky in the extended part of the
forecast at this time.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 1240 AM EST TUE DEC 10 2024

MVFR and IFR conditions will continue to overspread eastern Kentucky
from the southwest over the next several hours in association with a
warm frontal passage. This warm front will bring some fog ahead of
it, along with showers towards dawn, which will also overspread
the region from the southwest primarily beginning around 10Z and
lasting for several hours. This shower activity then continues
into the daytime hours. A few isolated thunderstorms are possible
in the afternoon hours, but confidence is too low to include any
mention in the TAFs, at this point. After 00Z Wednesday, an
approaching wave aloft will help usher in another round of
potentially IFR or lower conditions late in the period. Winds will
be light and variable into the morning hours before picking up
from the south by midday at around 5 kts. Look for a switch to
the northwest later in the evening at similar speeds.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...GREIF
LONG TERM...AR
AVIATION...CMC/GREIF

Source: JKL issues Area Forecast Discussion (AFD) at Dec 10, 4:45 AM EST (https://mesonet.agron.iastate.edu/p.php?pid=202412100945-KJKL-FXUS63-AFDJKL)

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