JKL issues Area Forecast Discussion (AFD) at Jan 1, 8:05 AM EST349
FXUS63 KJKL 011305
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
805 AM EST Wed Jan 1 2025
.KEY MESSAGES...
- Winter cold returns to start the new year and continues through
at least the next week.
- A weak, fast moving weather system may bring light snow
accumulations on Friday.
- A significant storm system may bring a mix of wintery
precipitation Sunday and Monday.
&&
.UPDATE...
Issued at 805 AM EST WED JAN 1 2025
Widely scattered rain/snow showers and patchy drizzle continue to
drop southeast across the area this morning. This activity should
generally transition over to mainly snow showers/flurries for
this afternoon and evening. The latest observations have been
blended into the near-term forecast, which has been sent to NDFD
and the web.
&&
.SHORT TERM...(Today through Thursday)
Issued at 501 AM EST WED JAN 1 2025
The first morning of 2025 is starting off on a raw and damp note
as light showers and patchy drizzle drift southeastward amidst
20-30 knot upslope flow at the 850 mb level. Temperatures are
primarily in the mid to upper 30s, though a few upper 20s/lower
30s are noted at elevations above 2,500 feet. Given the light snow
observed at Wise, VA, the high elevations of Pine, Log and Black
mountains are likely picking up on some light snow as well. The
latest surface analysis shows yesterday's cold front already off
the East Coast while cyclonic flow lingers over the Ohio Valley
under a broad 500H trough.
The broad upper level troughing will linger over the Ohio Valley
through short-term period. However, low-level ridging from the
surface up through 850 mb will translate from the southern/Central
Plains to the Ohio Valley/Southeast US on Thursday. As this system
approaches, the low-level flow will gradually turn from northwest to
westerly and turn drier. As a result, light upslope precipitation
will gradually become more confined to northeastern Kentucky by late
today and eventually taper altogether tonight. As temperatures at
the top of the moisture layer fall to near -10C (which is more
supportive of in-cloud ice crystals), locations should see the
ongoing liquid precipitation generally transition over to light
snow showers and flurries before ending. Any accumulation beyond a
dusting should be confined to the highest elevations of Pine and
Black mountains. As the high pressure builds in from the southwest
tonight, skies should clear at least partially, especially west
of I-75. After thinning for most locations on Thursday morning,
thickening clouds are forecast to return late in the day as the
next weak storm system approaches.
In sensible terms, look for stubborn clouds to persist into tonight.
Light showers/sprinkles and drizzle gradually flip over to a few
flurries or snow showers through the day then taper off slowly
from the southwest late today into tonight. Seasonably chilly
temperatures can also be expected, ranging in the mid 30s to
around 40 this afternoon. Tonight's lows are forecast to range
from lower 20s in sheltered valleys near/west of I-75 up to the
mid and upper 20s in the thermal belts and northeastern valleys.
Partial sun is expected on Thursday with highs generally in the
upper 30s to lower 40s.
.LONG TERM...(After midnight Thursday night through Tuesday)
Issued at 654 AM EST Wed Jan 1 2025
The first long term forecast package for Eastern Kentucky in 2025
features two bouts of wintery precipitation and much colder
temperatures than what we observed over the last few days of 2024.
On Thursday night into Friday, a quick-moving, clipper-type system
will move across the area from NW to SE. While this first system is
expected to produce scattered snow showers, they should be low-
impact due to the antecedent warmth and the quick forward motion of
the parent features. A second, stronger system will move into the
Greater Ohio River Valley at some point in the Sunday-Monday time
frame. This second system will be operating amidst a colder airmass,
and its more dynamic nature means that multiple precipitation types
could come into play. It remains too early to provide specific
details regarding accumulations and impacts, but interests with
early-week travel plans are strongly encouraged to keep in tune with
subsequent forecast updates.
System 1: Thursday Night Through Friday
The biggest question regarding the first winter weather event in the
long term forecast period is how much atmospheric moisture will be
present over the forecast area. The available higher-resolution
forecast guidance has begun to pick up on the idea of upper and mid
level moisture (and clouds) advecting into the area a little bit
faster than in previous forecasts. This has yielded in PoPs
beginning a little bit earlier on Thursday night, and with overnight
lows hovering at or just below freezing, snow would be the favored
precipitation type. However, the best low-level moisture is not
expected to arrive in Eastern Kentucky until the daytime hours on
Friday, when surface temperatures are forecast to rise above
freezing. While efficient cold air advection aloft will yield
favorable 850mb temperatures for snow on Friday afternoon, the
colder surface temperatures and the highest PoPs do not overlap.
This juxtaposition should limit snow accumulations across much of
the area to less than an inch, but the greatest chances for at least
half an inch of snow will fall within a crescent-shaped corridor
stretching across our northernmost and easternmost counties. The
colder forecast daytime highs and better low-level moisture closer
to the Ohio River will enhance accumulation potential north of the
Mountain Parkway. In a similar manner, surface winds will gradually
veer to a more WNW orientation as the parent disturbance swings
through, which could lead to marginal orographic enhancements in the
higher terrain along the Virginia border.
Overall, this first system looks fairly low-impact, but in typical
clipper fashion, a punch of colder air will advect into the area on
its backside. Canadian high pressure will nudge into the region on
Saturday, and despite clearer skies, highs on Saturday will struggle
to warm above freezing. Persistent cold air advection will allow
Saturday night's lows to dip into the teens, setting the stage for
the second system's approach on Sunday.
System 2: Sunday, Monday, and Beyond
Many more questions linger in the forecast for the second event.
Compared to this time yesterday, confidence has slightly increased,
but there remains a great deal of model spread, especially on Monday.
Ensembles have trended towards a surface low passing the the
northwest of the area on Monday, but the deterministic models
continue to bounce between faster/slower solutions. The guidance
suite should come closer to a consensus in the coming days as its
member models begin to ingest in-situ atmospheric observations
upstream. Right now, the parent features of this system are over the
data-sparse Pacific, which helps to explain the great deal of
observed model variability. Because of the colder and drier airmass
in place at the surface, confidence is fairly high that when
precipitation begins with this system, it will likely be snow.
However, there is strong signal in the guidance that warm air will
advect into the atmospheric column as the system evolves. The
magnitude of this "warm nose" will play a significant role in
determining what precipitation type falls in the latter stages of
this event, and the exact positioning of the system's surface low
and frontal boundaries will determine that. Thus, multiple layers of
uncertainty continue to shroud this forecast, and a wintery mix of
rain and snow remains in the grids for now.
As the system approaches, will be closely monitoring the progression
of a warm front moving north out of the Tennessee Valley. If this
boundary makes across the Kentucky state line, isentropic upglide
will introduce a warm nose to the thermal profile over much of the
forecast area. Any falling snow would then melt on its way down to
the surface, and the resultant precipitation type would depend on
the surface temperatures at that moment in time. If surface
temperatures remain below 32 degrees, freezing rain would be the
favored precipitation type. If the warm front clears a portion of
the forecast area and the surface temperatures there rise above
freezing, a plain rain would occur. If said front remains further to
the south, the influence of the warm nose would be muted, and more
of the area would see snow alone.
At the current moment in time, confidence in accumulating snow is
highest in areas along and north of the I-64 corridor. These
locations will be furthest away from the frontal boundary, and the
coldest forecast temperatures on Sunday and Monday across our
northern counties. A transition from frozen to liquid precipitation
types is likely to unfold somewhere within the southern half of the
CWA, but as the entire system ejects to the NE early next week,
wraparound moisture and upslope NW flow could yield a transition
back to snow. Stakeholders are encouraged to stay tuned to future
forecast packages, which will eventually include more specific
precipitation type details.
An even colder airmass looks to move into Eastern Kentucky behind
the second system. The Climate Prediction Center's 8-14 Day
Temperature Outlook highlights a greater than 90 percent chance of
below normal temperatures next week across our forecast area, and a
signal for a prolonged period of sub-freezing temperatures persists.
Readers are once again encouraged to review the winter weather
preparedness information available at weather.gov/safety/winter
before this active winter weather pattern takes effect.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
ISSUED AT 723 AM EST WED JAN 1 2025
MVFR conditions were observed at TAF issuance and that will remain
the case through most if not all of the daylight hours today. A
few snow flurries or sprinkles will be possible through this
afternoon, but most of the time should be dry. Ceilings are
expected to gradually improve to VFR from the southwest heading
into the evening and overnight. Westerly winds at 6 to 11 knots
along with gusts of 15 to 20 kts at times will continue through
this afternoon, before diminishing.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEERTSON
SHORT TERM...GEERTSON
LONG TERM...MARCUS
AVIATION...GEERTSON
Source:
JKL issues Area Forecast Discussion (AFD) at Jan 1, 8:05 AM EST---------------
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