JKL issues Area Forecast Discussion (AFD) at Dec 20, 6:24 AM EST558
FXUS63 KJKL 201124
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
624 AM EST Fri Dec 20 2024
.KEY MESSAGES...
- Light snow accumulations are forecast today and tonight
especially at 1500 feet elevation and above.
- Temperatures will warm early next week, leading to a possibility
of mainly rain from Monday night through Thursday.
&&
.SHORT TERM...(Today through Saturday)
Issued at 555 AM EST FRI DEC 20 2024
Early this morning, a mean trough at 500 mb extended from eastern
Canada across the Great Lakes and OH Valley into the southeastern
Conus. A shortwave trough extending from the western Great Lakes
to Lower OH valley was moving through this trough while ridging
extended from portions of the eastern Pacific and northern Mexico
into the southwest Conus and portions of the Great Basin. At the
surface, a clipper type low pressure system has track south of
Lake MI and was located near the IN and MI border with a warm
front east into OH and a cold front south into western KY to AR to
OK and then turned west in portions of the High Plains. A ridge of
sfc high pressure was centered near Albert and Saskatchewan and
extended into the Northern to Central Plains. Another ridge of
high pressure extended into the Southeastern Conus. Bands of low
and mid clouds have been crossing the area ahead of the
approaching front and shortwave trough with areas of clearing
yielding temperatures falling into the lower 30s while areas of
more substantial clouds were in the mid to upper 30s. A band of
precipitation reported as mostly rain and some mixed rain and
snow extended from Indiana into portions of Central KY.
Temperatures on Black Mountain have been in the upper 20s all
night.
Today and tonight, the main forecast challenge will be
precipitation types associated with passing clipper today into
tonight with elevation and surface temperatures largely driving
where accumulations occur and where impacts to travel may occur.
The general consensus of guidance is the band of precipitation
upstream will spread east and southeast into eastern KY this
morning to midday and then east of the area this afternoon. A drop
in temperatures at 850 mb is expected from levels initially in
the 0 to -3C range to about -7 to -10C in the afternoon to early
evening. After an initial band of more in the way of stratiform
precipitation this morning to early afternoon, the precipitation
should become more showery this afternoon. As temperatures aloft
cool, snow levels will drop from initial levels near 3500 feet to
the 1500 to 2000 feet around midday to mid afternoon and then
below 1000 feet late this afternoon to this evening. After the
initial drop in temperatures aloft and a round of showers mixed
with rain and snow or in some instances all snow in the highest
elevations during the afternoon to early evening, a lull in the
precipitation with what is left perhaps mixing with rain as 850 mb
temperatures rise a couple degrees C is expected from mid to late
evening. Toward midnight, another impulse should lead to renewed
snow showers late in the evening to the overnight hours as 850 mb
temperatures again dropping back to -8C to -10C areawide. Low
level moisture lingers through the night, but become more shallow
toward dawn on Saturday. Following recent mild weather for much of
the area snow accumulations should mainly be on grassy and
elevated surfaces, with some wet roads or rounds of slushy
untreated roads possible during the evening and overnight. Areas
at 1500 feet elevation and above will have the best chance of some
impacts to travel with chances for slushy or snow covered roads.
Impacts should be most widespread above 2000 or 2500 feet on top
of Pine and Black Mountains. No changes were made to the winter
weather advisory at this point with counties expected to
experience snow showers that have roads at and above 1500 feet are
included. If accumulating snow from snow showers were to linger
longer into Saturday as high res guidance such as some HRRR runs
suggest a few counties might need to be extended at a later time
if this later end time becomes the consensus. Overall,
accumulations for most of eastern KY should be less than a half of
an inch due to limited QPF when precipitation is all snow and
warm ground following recent mild weather. Areas generally at or
most likely above 1500 feet will have the best chance of picking
up 1 inch or more with 1 to 3 inches anticipated for areas
between about 1500 feet and 3500 feet including the higher passes
of Pine Mtn on US 421 in Harlan County, US 119 between Whitesburg
and Cumberland, and US 23 at the VA line/Pound Gap. The top of
Black Mountain may pick up in excess of 4 inches from this event.
Otherwise, with continued cold air advection on Saturday and
moisture linger into the DGZ, isolated to scattered snow showers
should linger into Saturday morning with some spotty light
additional accumulations. Otherwise, moisture may be sufficiently
deep for the snow showers to linger into the afternoon across the
north and east as suggest by some of the convective allowing
models such as the HRRR and FV3.
With the cold air advection expected from around midday through
the afternoon behind the cold front associated with the clipper
low passing to the north and northeast, highs for much of the area
will be in the morning, with steady or falling temperatures in the
afternoon. Very little rise is expected for highs on Saturday
compared to lows tonight, with lows in the upper 20s to around 30
for most areas below 2000 feet with highs in these areas on
Saturday in the low to mid 30s.
.LONG TERM...(Saturday night through Thursday)
Issued at 340 AM EST FRI DEC 20 2024
Saturday evening skies will continue to clear as the last system
pushes east. Clearing skies will allow for lows Saturday night to
drop into the teens. Quiet weather will remain through Monday, with
sunny skies and light winds. Highs Sunday will remain in the mid to
upper 30s, with lows in the teens to low 20s. Monday, and upper
level low over the Northern Plains will continue to push east
leading to southerly winds and increasing clouds through the day.
Highs will warm into the upper 40s to lower 50s. Lows are expected
to range in the lower 30s, however valley locations may decouple
prior to cloud cover moving in, resulting in colder valleys.
Tuesday, a low pressure to the north will bring shower chances to
the area though not much in the way of accumulating rain is
expected. Highs are forecasted in the upper 40s to low 50s, with
upper 30s at night.
Wednesday, an upper level low forms across eastern Oklahoma, and
another further west over the Great Basin. These systems will keep
rain chances around through the end of next week, as the 1st system
moves across Kentucky late Wednesday in to Thursday, and the next on
Friday. Light accumulations are expected. Highs Wednesday and
Thursday will be in the 50s, with some areas nearing 60 by Friday.
Lows each night will be in the upper 30s to low 40s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 1242 AM EST FRI DEC 20 2024
Conditions at TAF issuance were mainly MVFR. Some improvement to
VFR is possible overnight, especially the I-75 corridor west, and
perhaps as far east a KJKL. However, conditions will deteriorate
again on Friday as rain and snow develops. Winds will be easterly
veering to southerly tonight at 5 kts or less before turning
westerly and increasing to around 10 kts by late on Friday.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 10 AM this morning to 6 AM EST
Saturday for KYZ087-088-113-115-117-118-120.
&&
$$
SHORT TERM...JP
LONG TERM...GINNICK
AVIATION...GINNICK/GEERTSON
Source:
JKL issues Area Forecast Discussion (AFD) at Dec 20, 6:24 AM EST---------------
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