JKL issues Area Forecast Discussion (AFD) at Dec 16, 6:40 PM EST731
FXUS63 KJKL 162340
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
640 PM EST Mon Dec 16 2024
.KEY MESSAGES...
- Above normal temperatures persist through Wednesday.
- Periods of rain are forecast to impact the area at times through
Wednesday night.
- There is a chance for snow showers to develop by late Friday and
to persist into Saturday, mainly over southeastern portions of
Kentucky and especially in the higher terrain. At this time
little, if any impacts are expected.
- Below normal temperatures are forecast for this weekend.
&&
.UPDATE...
Issued at 639 PM EST MON DEC 16 2024
No significant changes were made, with minor edits to the diurnal
temperature curve.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 404 PM EST MON DEC 16 2024
A strengthening upper level low is present this afternoon in
western Ontario. This has led to lowering heights across the Ohio
Valley throughout the day as the trough axis passes through.
Meanwhile at the surface, the associated low has become strongly
occluded, with WPC analyzing the occlusion stretching as far south
as southern Wisconsin. The warm front associated with this system
passed through Kentucky this morning, bringing the first round of
rainfall to many locations. JKL is currently located in the warm
sector, behind the cold front and just ahead of the approaching cold
front at the time of this discussion. Rain has developed along and
just ahead of the front, which is currently traversing central
Kentucky and making its way to the western CWA border. With
temperatures in the upper 50s and low 60s, and lift present with the
incoming frontal boundary - along with the upper level trough,
enough instability is present that a few rumbles of thunder are not
out of the question as the precip moves into the western CWA.
Thunderstorms have been observed to our SW earlier this afternoon,
but have since tapered out. As we continue into the evening, and
quickly lose sunlight and daytime heating, any instability should
quickly fade, leaving mainly just rain in it's wake as the front
continues to move through.
The latest CAMs show the main line of showers starting to scatter
out by the time they reach overhead JKL this evening and overnight.
This is a bit of a downward trend from the previous global model
runs. Kept chance to likely pops across much of the CWA to start the
overnight, with the system expected to finally exit by the early
morning hours Tuesday. All pops should exit just after 12Z, though a
couple of the CAMs show some light showers holding on a couple
hours longer in the far SE.
The interesting thing about this system is that once it moves
through, we almost immediately go back to zonal flow. So not
expecting a strong pull of Canadian air into the region. High
pressure does move in from the west, and clouds do dissipate
throughout the day, however temperatures will still top out in the
50s (including some upper 50s in the south). This will be helped by
the fact that the high pressure will be so quickly moving that we
will be on it's west side by Tuesday afternoon. Meanwhile, another
shortwave will be developing to our west, leading to lowering
heights and SW flow taking hold aloft.
This shortwave will begin to impact Kentucky by Tuesday night,
bringing another round of clouds and showers to eastern Kentucky.
Models seem to have slowed down the onset a bit, mainly after 6Z.
Given that it's overnight, and temperatures will be in the upper 30s
and mid 40s, not too worried about thunder, and still too warm to
have snow. Given cloud cover both tonight and increasing tomorrow
night, did not really add in any ridge/valley splits.
Models did not point at any fog either, however, can't rule out
there could be pockets as rain comes to an end overnight, and
heading into the first part of tomorrow night. Will be something to
watch.
.LONG TERM...(Wednesday through Monday)
Issued at 508 PM EST MON DEC 16 2024
Our active weather pattern continues through the extended portion
of the forecast. Aloft, a series of storm systems will pass
through the Midwest and Ohio Valley within a west-northwest flow
pattern. At the surface, a quasi-stationary boundary will finally
shift eastward out of our area as a cold front Wednesday, all in
response to a positive tilted trough moving through the eastern
CONUS Wednesday night. A second storm system on the heels of the
first pass quickly through the Ohio Valley Thursday night into
Friday. Any precipitation and sensible weather will be behind the
reinforcing shot of cold air, arriving Friday night and Saturday
and associated with a third disturbance aloft that rolls into our
area.
With respect to significant, or hazardous weather, marginal
instability with MUCAPES of <750 J/kg but respectable 30-40 kts
of effective shear will allow for some minor chances of thunder
Wednesday along and ahead of the quasi-stationary surface boundary
mentioned previously. As far as snow is concerned in the Fri-Sat
time frame, impacts are not expected to be great at this time, if
any materialize. Precipitation in the form of rain and snow
showers will develop Friday, with precipitation changing to just
snow showers with time, late Friday afternoon into Friday night.
Some lingering minor chances of snow showers will exist into
Saturday. Probabilistic ensembles indicate only a 30-40% chance of
an inch of snow by Saturday, and that would be restricted to the
highest terrain across our southeast along the KY/VA state line.
With our recent warming and mild spell, expect any accumulation
would be limited to the higher elevation and mainly on grassy
areas and elevated surfaces. Perhaps a slick spot or two could be
possible on area bridges and overpasses if the cold air gets into
the area quick enough to freeze and residual water. Otherwise, we
could see some overnight lows temperatures in the teens Saturday
and Sunday night as eastern Kentucky receives a another solid
shot of much colder air for the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 639 PM EST MON DEC 16 2024
A cold front and associated rain shield will continue to work
through the area early this evening. This could lead to some
reduced visibilities, models are still showing anywhere between
IFR and MVFR CIGS. Even as the rain begins to exit east of the CWA
late tonight, CIGS will likely deteriorate a bit further along
the actual frontal boundary. Skies will finally begin to clear out
from W to E behind the front during the early morning hours.
During this time, can't rule out some fog - but models were not
overly pushing it. Conditions should quickly improve to VFR
moving into the day Tuesday as the system continues to depart to
the east, and high pressure takes hold for much of the day. SW
winds are present ahead of the frontal passage, gusting at times.
These winds should become more NWrly behind the frontal passage,
and will become more light and variable during the day Tuesday.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GINNICK
SHORT TERM...JMW
LONG TERM...RAY
AVIATION...GINNICK/JMW
Source:
JKL issues Area Forecast Discussion (AFD) at Dec 16, 6:40 PM EST---------------
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