JKL issues Area Forecast Discussion (AFD) at Dec 21, 12:01 PM EST957
FXUS63 KJKL 211701
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1201 PM EST Sat Dec 21 2024
.KEY MESSAGES...
- Snow showers taper to flurries by early afternoon, with local
accumulations up to a half inch possible near the VA border.
- Temperatures will warm early next week, with a possibility of
rain from Monday night through Thursday night.
&&
.UPDATE...
Issued at 1201 PM EST SAT DEC 21 2024
Mid day obs have been blended into the forecast-- without any
substantive changes.
UPDATE Issued at 1000 AM EST SAT DEC 21 2024
Flurries persist over southeast KY, with perhaps a few snow
showers still offering up enough to be measurable. However, no
additional significant accumulation is expected, and the Winter
Weather Advisory was allowed to expire.
UPDATE Issued at 707 AM EST SAT DEC 21 2024
Radar trends suggested that heavier snow showers would be more
confined to the VA border counties and this is supported by the
northwest to north northwest upslope flow. With some accumulation
anticipated in portions of Pike, Harlan, and Letcher counties,
the Winter Weather Advisory there was extended until 10 AM EST.
Moisture should become shallower by that point for only a few
isolated snow showers and flurries to remain in these areas. The
winter weather advisory was allowed to expire at 6 AM EST for
Knott, Perry, Leslie, and Bell counties as snow showers there
should generally be lighter and more isolated over the next couple
of hours before tapering to flurries.
&&
.SHORT TERM...(Today through Sunday)
Issued at 505 AM EST SAT DEC 21 2024
Early this morning, the axis of an upper level trough extended
from eastern Canada across the eastern Great Lakes to the mid
Atlantic to the Carolina and southeast US coast. This trough
encompassed much of the eastern Conus and portions of the central
Conus. A few weak shortwaves were moving through this trough with
one northwest of the Commonwealth at this time while another was
over the mid MS Valley. Further west , an upper level ridge
extended from the eastern Pacific across northwestern Mexico and
into the Rockies. At the surface, an area of low pressure was
moving north and northeast off of the Northeast U.S coast while a
ridge of high pressure was centered over western Ontario and
extended south through the MS Valley and was beginning to nose
into parts of the OH Valley. Cold air advection between the
surface low well to the northeast and the sfc ridge to the west
has resumed after a pause during the evening with 850 mb
temperatures analyzed around -7.5C near the VA border to -10C
over Fleming County. Flurries and bands of snow showers are
occurring at present with radar returns as far back to the
northwest as the OH River and southeast OH. KYTC webcam imagery
has indicated that some of the higher elevation roadways in
Letcher County have become snow or slush covered at times as the
heavier snow showers pass. Temperatures were generally below
freezing from about 1500 elevation in the southeast and across
some of the counties near and west of the Pottsville escapement.
Meanwhile, southeastern lower elevations and valleys were right at
freezing or a degree or two above. Elevations above 2000 feet
ranged through the 20s.
Cold air advection will continue today as the upstream shortwave
passes eastern KY early and the second to the southwest passes
toward the TN Valley and Southern Appalachians and the axis of
the upper level trough shifts to Quebec and the Northeast Conus
today while the shortwaves lead to the axis further to the south
remaining near the Mid Atlantic to Southeast U.S. coast. 850mb
temperatures are progged to fall to -10C to -12C areawide this
afternoon, before warm air advection at those levels toward
evening. With varying degrees of moisture progged among the models
this morning into the afternoon, but CCA and moisture into or
near the DGZ should favor strato cumulus and cumulus and at least
flurries from these lingering well into the day until about the
time the 850 mb warming commences. Isolated to perhaps scattered
snow showers should also occur for areas nearer to the WV border
this morning and especially the Pike to Harlan county area along
the VA border. Additional QPF will be minor, but fluffy dusting to
a half of an inch of accumulation appears possible this morning.
Temperatures will rise only a few degrees with very limited solar
insolation as winter begins under the cold advective pattern.
Highs in the low to mid 30s are anticipated with locations above
2000 feet not getting out of the 20s. Readings of this magnitude
are about 10 to 13 degrees below normal for December 21st.
With these some at least localized accumulations in snow showers
and the potential for some travel impacts on higher elevation
roadways for Pike Harlan and Letcher counties potentially
lingering past sunset, radar returns will be monitored over the
next hour for possible adjustments to the Winter Weather Advisory.
Low level moisture should gradually decrease by the evening into
the overnight as the upstream ridge of sfc high pressure builds
into the Great Lakes and OH Valley to southeastern Conus preceding
the upper level ridge building further east into the Plains/
Central Conus. Height rises/shortwave ridging building further
into the eastern Conus including the Commonwealth is anticipated
for tonight and into Sunday. Assuming sufficient clearing, a
rather chilly night is anticipated with mid teens to around 20
degrees for lows on average. The airmass will begin to moderate on
Sunday as 850 mb temperatures rise toward -5C if not warmer on
Sunday. However, following the cold start, temperatures should
only peak about 3 degrees warmer on Sunday compared to today.
.LONG TERM...(Sunday night through Friday)
Issued at 420 AM EST SAT DEC 21 2024
Sunday night, the area will be under clear skies and light winds
with zonal flow aloft. Lows Sunday night are expected to drop into
the teens and low 20s, with little to hinder radiative cooling. Dry
conditions will continue through Monday, with highs in the mid to
upper 40s. A few spots may scratch 50.
An upper level trough coming out of the northern plains, will
approach the state through Monday, leading to increasing clouds
toward sunset, starting in the northwest, slowly working southeast.
Lows Monday night are expected to be warmer in the low to mid 30s.
Tuesday, the upper level low progresses over New York and
southeastern Canada, with a trailing cold front extending south and
west across the Ohio Valley. There's currently a slight chance of
rain showers across the Blue Grass area of eastern Kentucky. Light
accumulations are anticipated. Highs are forecasted in the upper 40s
to low 50s, with lows in the mid to upper 30s.
Wednesday, a different trough deepens over the Oklahoma-Texas region,
while an offshore-low is located off the California coast. This
trough across Oklahoma and Texas progresses north and east effecting
mainly western and central parts of Kentucky, however there are
shower chances across southwestern portions of the forecast area,
such as Rockcastle, Pulaski, and Wayne counties. Highs during the
day are forecasted to range in the mid 50s, with lows in the upper
30s to lower 40s.
Thursday, some models have the previous system lingering across
eastern Kentucky, with low shower chances remaining. Meanwhile, the
coastal low from California, moves onshore and is modeled to arrive
across eastern Kentucky late Thursday night through Friday, bringing
more shower chances to the area. Highs Thursday and Friday are mid
to upper 50s, with some 60s, while lows at night remain in the lower
40s.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 1201 PM EST SAT DEC 21 2024
Ceilings are still present over most of the JKL forecast area at
mid day, but had broken up immediately to our northwest. The
ceilings are mostly low end VFR, but there are some pockets of
MVFR in southeast KY. There are also a few flurries remaining in
southeast KY.
Any remaining MVFR ceilings should rise to VFR this afternoon, and
the trend for decreasing clouds will progress southeast. Ceilings
will be gone in most places by 01Z. Flurries will also taper off
this afternoon. Once ceilings break up, mostly clear skies and
VFR conditions are forecast through the remainder of the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...HAL/JP
SHORT TERM...JP
LONG TERM...GINNICK
AVIATION...HAL
Source:
JKL issues Area Forecast Discussion (AFD) at Dec 21, 12:01 PM EST---------------
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