JKL issues Area Forecast Discussion (AFD) at Dec 31, 2:54 PM EST071
FXUS63 KJKL 311954
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
254 PM EST Tue Dec 31 2024
.KEY MESSAGES...
- Well above normal temperatures today will be followed by a
return to winter cold to start the new year.
- Quick-moving low pressure will bring another light round of
rainfall on today along with strong south to southwest winds
gusting to between 30 and 40 mph at most locations.
- Any thunderstorms this morning/early afternoon could become
strong to severe with damaging winds and large hail possible; an
isolated brief tornado cannot be ruled out.
- A fast-moving clipper system may bring light snow accumulations
to the forecast area on Friday.
- A dynamic storm system may bring a mix of wintery precipitation
types to Eastern Kentucky next Sunday and Monday.
&&
.UPDATE...
Issued at 1043 AM EST TUE DEC 31 2024
Initial round of discrete low-topped supercells has weakened
and/or moved out of the area. A broken line of thunderstorms is
now developing along the western part of the CWA and will move
east across the area over the next few hours. These storms will
efficiently mix strong winds from aloft to the surface, possibly
exceeding 50 mph in gusts in some locations. There is also
sufficient wind shear to warrant a Marginal Risk for severe
thunderstorms. While highly unlikely, an isolated spin-up tornado
can not be ruled out through mid-afternoon before the activity
moves out of the area to the east and northeast.
UPDATE Issued at 851 AM EST TUE DEC 31 2024
SPC has issued a Marginal risk for severe weather across most of
eastern Kentucky today. All modes of severe weather (hail, wind,
and tornadoes) are possible. The latest observations have been
blended in the hourly forecast.
&&
.SHORT TERM...(Today through Wednesday)
Issued at 531 AM EST TUE DEC 31 2024
Temperatures are holding steady or rising early this morning as
clouds and winds increase ahead of an incoming storm system.
Temperatures as of 10z, ranged from the mid 30s in the coldest
northeastern hollows to the mid/upper 50s near and west of I-75 and
I-64 north. Regional radar shows an area of showers, with a few
embedded thunderstorms, lifting through the Lower Ohio Valley ahead
of a warm front that extends from an ~994 mb surface low over
Illinois southeastward to the vicinity of Lake Cumberland and then
southward into Tennessee. A cold front is evident behind the warm
front, extending from the low toward the Gulf of Mexico, just east
of the Mississippi River.
Model guidance is in good agreement showing this area of low
pressure skimming just north of the Ohio River today and approaching
the southern shore of Lake Erie by mid-evening. As the low passes,
the associated warm conveyor belt jet (50+ knots @850mb) will help
propel the warm front through eastern Kentucky this morning. Our CWA
will be briefly in the warm sector until the trailing cold front
sweeps through during the early to mid afternoon. Various model
solutions show a narrow tongue of of modest surface-based shallow
instability within the warm sector. Meanwhile, the presence of the
strong wind field around the low should yield sufficient EBWD (up to
~35-40 kts) to maintain supercellular structures. While the latest
NAM12 remains quite modest with just a couple hundred J/kg of skinny
instability, the RAP13 has suggested up 500 J/kg of surface-based
instability, a significant portion of which is in the hail growth
zone. If any shallow supercells develop within the warm sector,
there will almost certainly be a risk of small hail. Additionally,
low MLLCLs, up to ~180 J/kg 0 to 3km CAPE, and modest turning in the
low-level hodograph (at least in the RAP13) would suggest that
tornadogenesis cannot be ruled out should a sustained supercell
develop. Also, multiple model soundings now show the equilibrium
levels rising above -20C, warranting the addition of thunder to
today's forecast.
Aside from the possibility of thunderstorms, gusty winds are likely
to develop as low-level lapse rates steepen in the warm sector under
diurnal heating later this morning and then remain steep this
afternoon due to cold air advection behind the cold front. BUFKIT
momentum transfer suggests that south to southwesterly gusts will be
strongest between roughly 10 AM and 3 PM EST before subsiding later
in the afternoon. Forecast wind gusts were marginally strong enough
to warrant the issuance of a Wind Advisory for most of eastern
Kentucky from 8 AM through 7 PM EST. Another brief uptick in the
wind gusts is possible this evening, but speeds should generally
remain below advisory criteria. The surface low pressure responsible
for this inclement weather will continue lifting away into western
New York tonight but moisture will continue to wrap in around the
backside of the low. This low-level moisture combined with upslope
flow will keep light showery precipitation across the area
overnight. As 850mb temperatures fall to between ~-5 to -8C by late
tonight, anticipate that showers will mix with and change over to
snow for most locations, first over the mountaintops near the
Virginia border and also north of I-64. By late Wednesday morning,
expect all precipitation to be falling in the form of snow. Snow
showers and flurries can be expected to continue through the
afternoon on Wednesday amidst northwest upslope flow lingers behind
the departing low pressure. Given warm ground temperatures, snow
accumulation will likely be minimal to nil outside of the highest
mountains.
In sensible terms, look for showers to pass through eastern Kentucky
this morning, possibly with a embedded rumble of thunder.
Temperatures will warm well into the 50s for a time once the warm
front passes and skies may clear partially, especially late morning.
South to southwesterly winds will become gusty, peaking between 30
and 40 miles per hour at most locations. If a thunderstorm develops
during this time, it could become strong. Any sunshine will be short-
lived as clouds thicken and showers redevelop during the early to
mid-afternoon and temperatures will drop back into the 40s. Showers
continue through tonight and gradually mix with and change over to
light snow showers/flurries at most locations as temperatures dip
into the middle 30s at lower elevations and into the lower 30s to
upper 20s above ~1,500 feet. Any remaining rain showers in the
deepest valleys of the Big Sandy basin will switch to snow on
Wednesday morning. Snow showers and flurries are then expected to
continue for the remainder of Wednesday while temperatures hold in
the mid to upper 30s at lower elevations and in the upper 20s to
lower 30s above 2,500 feet. Little or no snow accumulation is
expected, except perhaps an inch or two over the highest portions of
Big Black and Pine mountains.
.LONG TERM...(Thursday through Tuesday)
Issued at 252 PM EST TUE DEC 31 2024
Thursday, dry conditions can be expected under partly to mostly
cloudy skies, with highs in the upper 30s to low 40s. Westerly winds
are expected to be fairly light. As quiet conditions remain across
Kentucky, a short wave "clipper" type system begins to project
eastward, out of the Pacific Northwest. This clipper system is
currently expected to reach eastern Kentucky during the overnight
hours Thursday, into Friday. Lows are forecasted in the upper 20s to
low 30s.
As an upper level trough deepens over eastern Canada, cold air will
begin to usher into the Ohio Valley. Guidance suggests air aloft
will be cold enough for snow showers overnight to overspread the
area, tapering off Friday. Winds gradually veer southwesterly, early
Friday, to northwesterly during the afternoon. In general, northwest
flow may help aid in orographic support, and in turn enhance some
snow showers to linger a bit longer into the afternoon hours. Minor
impacts will be possible, with areas east of I-75 having a 40-65%
probability of seeing at least half an inch of snow, and a 10-25%
probability of seeing over 1 inch. Highs Friday, are being
forecasted in the mid to upper 30s, as cold air settles into the
area for the next few days. Lows Friday night are expected to drop
into the teens.
Saturday, looks to be a transitionary day as the previous clipper
system continues to push east out of the area, while the next system
over the Great Basin begins its southeastward propagation towards
Kentucky. Highs Saturday will remain chilly, scratching to get to
30 in most places. Lows will remain chilly in the teens.
As the next dynamic system approaches, timing and placement will
play a key role in the states weather. Effects from this system
could be seen as early as Sunday, tapering off Tuesday morning.
Model to model runs have been jumping around on solutions, so
forecasting confidence on specifics remains shaky. What is important
to note or highlight is the variety of possible outcomes. At the
onset of precipitation, the antecedent coldness throughout the
column appears to favor snow. However, it remains uncertain how much
warm air will advect into the atmospheric column ahead of a surface
warm front pushing north out of the Tennessee Valley. If this
boundary makes it to Cumberland River Basin, isentropic upglide will
introduce a warm nose to the thermal profile over much of the
forecast area. If the parent low takes a more northwesterly path and
said boundary moves closer to the I-64 corridor, the area may
transition fully into the warm sector of this system. If the surface
low takes a more southeasterly track and the boundary remains closer
to the Tennessee River, less warm air would make it into the
atmosphere over our forecast area. The first solution would yield in
a messier precipitation type forecast, with a transition from snow
to ice to rain and then back to snow possible. The second solution
would lend itself to rain during the warmer afternoon hours,
although probabilistic ensemble data suggests that the likelihood of
this is decreasing. The third solution could result in enhanced snow
accumulations, but the 10 to 15 degrees of model spread in the
temperature forecast for both Sunday and Monday afternoons means
that it is far too early to forecast specific accumulation totals
for any precipitation type. Interests are encouraged to stay tuned
to future forecast packages as the guidance suite ingests higher
quality upstream observations and comes towards a consensus in the
coming days. Highs Sunday through Tuesday generally range from the
30s to low 40s, with lows at night in the teens to low 20s.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 1224 PM EST TUE DEC 31 2024
Cold front with a line of showers and thunderstorms producing
strong gusty winds will exit east of the area by 20z. Otherwise, light
showery precipitation is expected to linger well into the
overnight while ceilings drop to low MVFR/IFR for much of the
remainder of the TAF period.
Strong south to southwest winds ahead of the front will veer more
westerly to west-northwesterly behind the cold front this
afternoon and then slowly subside this evening and tonight.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CMC
SHORT TERM...GEERTSON
LONG TERM...GINNICK
AVIATION...CMC
Source:
JKL issues Area Forecast Discussion (AFD) at Dec 31, 2:54 PM EST---------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!
