JKL issues Area Forecast Discussion (AFD) at Dec 19, 10:17 AM EST997
FXUS63 KJKL 191517
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1017 AM EST Thu Dec 19 2024
.KEY MESSAGES...
- Light snow accumulations possible with a weather system Friday
and into early Saturday.
- Temperatures will warm early next week, leading to a
possibility of rain by Christmas Eve into Christmas Day.
&&
.UPDATE...
Issued at 1017 AM EST THU DEC 19 2024
Overnight and early morning temperatures did not get as cold as
was forecast, which is affecting today's diurnal temperature
curve. Have raised morning temperatures, but left afternoon max
readings alone for now due to clouds holding on and uncertainty
about how much warming will occur.
Have also changed tonight's precip type to drizzle with a POP less
than 20%. The drizzle is being mentioned over roughly the
northwest half of the area. Forecast soundings show low level
saturation in warm air advection toward dawn, with cloud temps
too warm for ice formation.
&&
.SHORT TERM...(Today through Friday)
Issued at 400 AM EST THU DEC 19 2024
Current surface analysis across the CONUS is rather quiet. The front
that crossed through yesterday is oriented along the eastern
seaboard. Surface high pressure exists behind the cold front and
that's what's parked over much of the eastern CONUS. To the
northwest of the CWA, the next system is moving out of southern
Canada into the Dakotas. Locally, low clouds are in place across the
region, this has kept temperatures from plummeting; however, lows
will still bottom out in the low to mid-30s.
Surface high pressure will remain in place today leading to dry
weather; however, continued low-level cloud cover will limit warming
today. This will keep daytime highs in the low to mid-40s. Aloft, an
85-90 kt jet-streak will dive southeast out of the Rockies into the
Central Plains. At the surface, this clipper system will track out
of southern Canada into the Dakotas then eject into the southern
Great Lakes/Ohio Valley. As this low tracks closer to the area,
surface high pressure will eject off to the east and will be
replaced with this approaching clipper. However, before that
happens, overnight lows will fall into the low to mid-30s.
Friday will bring that clipper system into the Ohio Valley.
Increasing PoP will move into the CWA first thing Friday morning.
First starting as rain then transitioning to rain/snow then all snow
by the end of the forecast period. Forecast critical thicknesses and
soundings show that the transition to all snow will be rather quick
as colder air filters into the region. Current forecast has rain
changing to snow roughly after 21Z which could be sooner as the
column cools due to falling snow. Light snow accumulations will be
possible through the end of the forecast period as rain changes to
snow; however, the bulk of the snowfall is forecast to be in the
long-term forecast but winter weather headlines may be needed as
accumulations look to meet advisory level criteria.
.LONG TERM...(Friday night through Wednesday)
Issued at 258 AM EST THU DEC 19 2024
Light upslope and flurries continue into the evening and overnight
Friday night, with low-level cold advection continuing. Several
models indicate a brief period of a few hours of re-moistening of
the dendritic growth zone late Friday night or early Saturday
morning (pre-dawn), which could result in a brief period of light,
yet more significant, accumulating snow, especially where there
is orographic forcing. A passing disturbance during the day
Saturday will also help some overall synoptic lift to wring out
any light snow or flurries, so for the favored upslope areas of
southeastern Kentucky it may take until Saturday after dark to
completely end the flurries.
Nevertheless, by Sunday the jet stream aloft begins to retreat north
and east as mid-level heights rise. Thus, after a chilly night
Sunday night in the teens for lows, temperatures will begin a steady
upward trend as warm advection and a more southwesterly flow aloft
begins to develop and then strengthen. The next system arrives
Christmas Eve (Tuesday), with models suggesting a stationary front
along the Ohio River Valley serving as a focal point for rain at
least initially. However, there are significant uncertainties
between operational models for this time period that still need to
be resolved, but the NBM shows high-end chance to low-end likely
PoPs peaking Tuesday night into Christmas Day for the area. One
thing that can be said with confidence is that temperatures will be
mild with this system, with highs in the 50s Tuesday into Wednesday
(Christmas) and lows in the 40s.
&&
.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 633 AM EST THU DEC 19 2024
All terminals are currently MVFR and will remain MVFR for a few
more hours before terminals begin to improve into VFR after
18Z. CIGS will improve with clouds diminishing Thursday evening
but an approaching system will cause TAFs to fall back into
categorical MVFR for the end of the TAF period. Winds will be
light and variable through the TAF window.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...HAL
SHORT TERM...VORST
LONG TERM...CMC
AVIATION...VORST
Source:
JKL issues Area Forecast Discussion (AFD) at Dec 19, 10:17 AM EST---------------
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