JKL issues Area Forecast Discussion (AFD) at Dec 25, 7:07 AM EST
782
FXUS63 KJKL 251207 AAA
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
707 AM EST Wed Dec 25 2024
.KEY MESSAGES...
- A warming trend is expected through the rest of the week.
- Widespread rainfall, potentially locally heavy at times, is
forecast Saturday afternoon and night.
&&
.UPDATE...
Issued at 705 AM EST WED DEC 25 2024
Hourly grids were updated based on recent observations and trends.
This led to no substantial changes at this time.
&&
.SHORT TERM...(Today through Thursday)
Issued at 525 AM EST WED DEC 25 2024
Early this morning, a shortwave ridge axis extended from east of
the FL peninsula north northwest into the Southern to Central
Appalachians to the Great Lakes, while a shortwave trough was
traversing the Lower OH Valley. Another shortwave trough extended
through the Central Conus from the mid MS Valley to eastern TX
with a narrow shortwave ridge to its west and to the east of a
trough working across the Northern Rockies to Great Basin
vicinity. An additional trough upstream of that was approaching
the west coast of the Conus. At the surface, an area of low
pressure was centered over northeast TX/Arklatex vicinity with a
weak stationary boundary north to the mid MS valley and then east
near the OH River. Mid and high clouds have moved across southern
sections of eastern KY overnight, while more in the way of low
clouds were further north and nearer to the sfc boundary. Some
light showers or sprinkles have been moving across northern to
northeastern sections of KY.
Today and tonight, the initial shortwave trough is expected to
move north and east of the area into OH and WV this morning while
the next shortwave trough gradually moves into the eastern Conus
and approaches the Commonwealth from the southwest tonight. This
trough axis should work across the Lower OH Valley Thu morning to
midday and then east of eastern KY on Thu afternoon. A weak
shortwave ridge should move into the Commonwealth behind that
shortwave and in advance of the next trough that moves from the
Great Basin to the Central Conus from today into Thursday. At the
surface, the area of low pressure over northeast TX/Arklatex
region should generally begin to weaken/fill as the associated mid
and upper level system outruns it toward the OH and TN Valley
later tonight and into early Thursday. The stationary boundary
near the OH River should remain in place today and into tonight
before becoming diffuse by Thursday. Also tonight, as the system
moves from the Great Basin and into the Plains an area of low
pressure should develop to the lee of the Rockies in the High
Plains of CO/NM/KS/OK/TX area and then track across TX toward the
Arklatex region on Thursday.
With the shortwave trough passing by to the north and northwest
today and the surface boundary in the vicinity and generally
nearer to more northern locations, low and mid clouds will be most
prevalent there. Isolated to possibly scattered showers and some
sprinkles are anticipated from this for northern areas generally
near and north of the Mtn Parkway for Christmas Day through this
evening. A period of shortwave and sfc ridge of high pressure
dominating will lead to precipitation free weather for all areas
late tonight and into Thursday.
South the stationary boundary that becomes diffuse, temperatures
will remain mild through the near term period with temperatures
climbing about 5 degrees above normal today and 10 degrees or more
above normal on Thursday. Lows tonight should be mild with passing
clouds and dewpoints in the 30s resulting in lows in the mid 30s
to around 40.
.LONG TERM...(After midnight Thursday night through Tuesday)
Issued at 603 AM EST WED DEC 25 2024
A busy pattern emerges, with more rain chances than not through the
extended period. In fact, Thursday, the first day of the period,
will likely be one of only two possible dry days, and even then
models are hinting at precip developing just to the north and west
of the CWA. By Thursday night, a upper level low and surface low
emerges across the Lower Mississipi Valley. As this system lifts
northeast, it will result in a strong influx of moisture on it's
east side, including much of Kentucky. Being so close to the
system's center, the influx of moisture will bring likely to
widespread pops by late Friday and Friday night. Based on the latest
ECMWF, it appears as though a frontal boundary also develops with
this low, traversing eastward across Kentucky and amplifying the
lift and precip Friday and Friday night. At this point the upper
level low cycles and starts moving directly northward, keeping the
remnants of the boundary across eastern Kentucky into Saturday
morning. This will also result in continued precip chances during
this time.
Meanwhile, energy will be increasing to our SW as a new upper level
system and surface low materialize across the Southern Plains. Large
scale troughing will quickly develop across the Central Conus as a
result, leaving the Ohio Valley in deep SW flow. In addition, much
of the Deep South and into the Ohio Valley will be to the east of
this strengthening low through Saturday night, creating deep S to SW
flow. This will amplify the amount of warm air and moisture
advection. Models, including the NBM, show a second surge of likely
to widespread pops through Saturday night as a result.
By Sunday morning, the axis of the trough and upper level
low/shortwave, plus the surface low pressure system, will be
directly overhead of Kentucky. The best moisture, the front, and the
warm air will be exiting to the east during the day, though pops
associated with the center of the low pressure center will likely
linger through the day and into the overnight. However, by Sunday
night, winds will be becoming more northeasterly and cooler air will
begin advecting in on the backside of the upper level trough. There
is still a bit of disagreement on when the lingering moisture will
finally exit east of the CWA, so kept closer to the NBM with chance
pops continuing through Monday morning. The latest GFS is quite a
bit quicker than the ECWMF, so expect pops through this time period
to either increase or decrease based on which solution the models
trend toward.
Both models do agree that an area of high pressure will move through
during the day Monday, giving us a second day of mostly dry weather
(especially if the quicker exit of the GFS pans out in the morning).
Both models also agree on a large system developing across the
Central Plains during the day Monday, and quickly moving towards the
Ohio Valley. Unfortunately, the Ohio Valley is a large region, and
their agreement on placement as it does move eastward is quite
different. Either way, moisture advection starts to increase from
the Gulf of Mexico and northward into Kentucky as it nears.
Obviously, this far out in the forecast, uncertainty is quite low
and models will likely go through quite a few changes. Stuck with
the NBM for pops as a result, but do have enough confidence to
expect some impact in the form of precipitation across the state
heading into the day Tuesday. Even the NBM is going likely across
much of the CWA, which is impressive given the model track
disagreement.
As far as temperatures, the overall pattern shows quite a bit of
warm air advection through the extended, which will keep
temperatures well above normal. Overnight temperatures will be aided
by cloud cover as well many nights, keeping them more moderate. The
warmest day will be Saturday, with the strongest SW flow and WAA in
place. Morning lows will be in the low 50s for most places, and
highs will top out in the mid 60s. Because of this, and also because
of the weakening boundary overhead, did introduce some slight chance
thunder chances. However, admittedly confidence is fairly low on
this. Sunday temperatures will be similar for morning lows and only
a few degrees cooler for afternoon highs, as colder air begins to
advect in during the afternoon. Monday and Tuesday will be some 10
degrees cooler than the weekend, however based on the current NBM,
we could still see highs in the 50s both days. This may shift a bit
depending on model trends, but there is enough agreement to suggest
we will remain at or above normal, nevertheless.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
ISSUED AT 705 AM EST WED DEC 25 2024
A disturbance will depart to the northeast of eastern KY to begin
the period while another disturbance will approach late in the
period. The remnants of a weak frontal boundary will also linger
across the region as well. These features will combine for some
low and mid clouds at times, with a general trend toward less low
clouds during the first 6 hours of the period behind the initial
disturbance. The initial low clouds and perhaps a brief period of
MVFR ceilings could affect KSYM, KJKL, and/or KSJS to begin the
period. Winds will be light and variable in general through the
period, but generally from the east to southeast.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...JP
LONG TERM...JMW
AVIATION...JP
Source: JKL issues Area Forecast Discussion (AFD) at Dec 25, 7:07 AM EST (https://mesonet.agron.iastate.edu/p.php?pid=202412251207-KJKL-FXUS63-AFDJKL-AAA)
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