JKL issues Area Forecast Discussion (AFD) at Dec 25, 4:03 PM EST573
FXUS63 KJKL 252103
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
403 PM 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.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 403 PM EST WED DEC 25 2024
General upper level ridging is present from the Great Lakes to
southeast CONUS late today, and will remain in place during the
short term period. Surface high pressure is centered near the St.
Lawrence Valley and New England and is ridging southward east of
the Appalachians, with cold air damming starting to set up east of
the mountains. A stationary front is north of the Ohio River. For
our area, the low level flow is bringing near neutral or weak
warm air advection.
Little change is expected in terms of effects on our local weather
during the period. There will be some short wave troughs rippling
into/through the upper ridge. One of these is currently over the
lower Mississippi Valley, and another one is over CO/NM. The first
one will dampen/attenuate as it move into the ridge and toward us.
It could enhance precip potential near/north of the front, but is
not likely to give us anything more than clouds. The second wave
will approach Thursday night, but at this time it looks like
associated precip will remain to our west through Thursday night.
.LONG TERM...(Friday through Wednesday)
Issued at 200 PM EST WED DEC 25 2024
The forecast period begins with the area sitting in the warm sector
of an approaching upper-level shortwave. Aloft, a shortwave trough
and surface low will be centered over the Ark-La-Tex region, this
trough and surface feature will quickly eject into the Ohio Valley
bringing a surface cold front to the doorstep of the CWA. Increasing
showers are likely through the day Friday with an isolated
thunderstorm will be possible Friday night. Upper-level support
fizzles out and abandons the surface low with its associated
boundaries to the east of the forecast area; leading to continued
rain threats into Saturday. Quickly following on the heels of the
first shortwave, another fast moving jet maxima will eject into the
area and pick up the abandoned surface feature and drag it closer to
the CWA. Again, this will keep persistent shower and thunderstorm
activity in the forecast through the day Saturday into Sunday night.
Like the movie Groundhog Day, this upper-level support is forecast
to fizzle out with a third shortwave developing causing surface
cyclogenesis on the abandoned cold front before this third, stronger
shortwave pushes the new surface low through the area through the
day Sunday before exiting late Monday morning. Since the area will
be under constant southwesterly flow, increasing Gulf moisture will
surge into the region leading PWs to climb into 1.00" to 1.50"
range, which is in the 90th percentile for this time of year and
could lead to localized hydro issues. Rainfall totals through this
weekend are forecast to range from 1.00" along the eastern high
terrain, less due to rain-shadowing due to southeasterly flow and
downsloping, to a little less than 2.00" along and west of the I-75
corridor and Cumberland Plateau.
Weak surface high pressure builds in quickly behind the exiting
surface low for Monday; however, another system will quickly
traverse the CONUS and be on the doorstep of the CWA by Tuesday
morning. This morning's model suite has come into a little bit
better agreement on the placement and timing of this New Year's
system. Both the GFS and ECMWF both have the low centered over the
Mid-Mississippi Valley by midday Monday and quickly moving east
through the day before bringing increased PoP for Tuesday morning.
However, models begin to diverge going into the day Tuesday as the
GFS pivots to the northeast and takes the center of the low into the
Ohio Valley. The ECMWF, dives southeast and takes the center of the
low through the Tennessee Valley. This difference in track will play
a role in the precipitation type for the end of the period as the
ECMWF would be the colder system leading to possible backside snow
showers as thicknesses would favor that potential. The GFS would be
the warmer solution leading to all rain. Since this is well into
next year, opted to stick with the NBM past Tuesday.
Overall, the period will be highlighted by multiple rounds of
showers thunderstorms leading to widespread heavy rainfall which
could prompt hydrologic headlines. Temperatures will run above
average for the entire forecast period leading to a warm and wet end
to 2024 and start of 2025.
&&
.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
ISSUED AT 155 PM EST WED DEC 25 2024
VFR conditions and light winds are forecast through the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...HAL
LONG TERM...VORST
AVIATION...HAL
Source:
JKL issues Area Forecast Discussion (AFD) at Dec 25, 4:03 PM EST---------------
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