JKL issues Area Forecast Discussion (AFD) at Dec 10, 12:40 AM EST047
FXUS63 KJKL 100540 AAA
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1240 AM EST Tue Dec 10 2024
.KEY MESSAGES...
- Mild temperatures will last through this afternoon, with a
brief blast of much colder air then arriving at mid week behind
a cold front.
- Showers will accompany a cold front on later today into tonight.
- Minor, light snow accumulations are possible Wednesday into
Wednesday night.
&&
.UPDATE...
Issued at 1133 PM EST MON DEC 9 2024
Late evening update is out with minor changes. Made some minor
edits to PoPs, mainly after 06z. Warm frontal passage will
bringing low ceilings and possibly some fog into the overnight,
especially on the ridges, followed quickly by a round of numerous
to widespread showers.
UPDATE Issued at 729 PM EST MON DEC 9 2024
Early evening update is out. Lowered the 15 and higher PoPs to
less than 15 in the grids to remove from the point-and-click
forecasts for the remainder of this evening. Other changes
resulted in little to no impact to the overall forecast. Did blend
in the latest observations to use as the starting point for the
updated forecast. Will analyze the 00z model runs and update
accordingly for the late evening update.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 429 PM EST MON DEC 9 2024
A weak, nearly stalled surface frontal boundary is near the
western edge of the JKL forecast area late today, with mild air
(temps near 60) in place in eastern Kentucky on the warm side of
the boundary. Aloft, a very large, broad trough covers the CONUS,
with an embedded impulse moving southeast over the central plains
and central Rockies. This impulse is amplifying the upper trough
and supporting a stronger cold front which is further upstream
from us.
The trough will continue to amplify and slowly shift east during
the short term period. It will support a developing surface low
which will track northeast along our current frontal boundary,
passing over KY on Tuesday. A continuing influx of mild, moist air
along/ahead of the front, along with the advancing upper trough,
will result in showers spreading north into the area on Tuesday as
the surface low approaches. NAM soundings also indicate weak
instability developing for most of the area ahead of the front,
and a slight chance of thunder has also been included.
As the low passes and departs, it will pull in colder air which
is currently behind the upstream cold front, with our temperatures
then returning to more December-like readings. However, it
appears that any change to snow for remaining precip will hold off
until after the short term period.
.LONG TERM...(Wednesday through Monday)
Issued at 315 PM EST MON DEC 9 2024
Wednesday, a high amplitude ridge-trough pattern is modeled across
CONUS, with a ridge located over the west coast, and a trough
spanning from Manitoba down to the Texas/Louisiana area.
Throughout the day, the ridge over the west begins to break down,
while the trough becomes negatively tilted. 500 millibar heights will
begin to fall through the afternoon, briefly dropping below the
540mb height threshold, commonly used to identify possible
transitions in precipitation type. Moisture surging north ahead of
the trough will start off as rain showers across eastern Kentucky,
before transitioning to a wintry mix, followed by light snow showers
during the late morning, early afternoon. Highs for the day are
forecasted in the upper 30s to low 40s, with lows that evening
dropping into the low 20s, with teens across the Bluegrass area. Any
snow accumulation will likely occur on grassy surfaces, with very
minor road impacts, given highs Tuesday are expected to be in the
60s. Heaviest QPF's across the area occurs in the morning hours,
prior to the cold air being established. Ensemble and probability
guidance shows a gradual increase in probability of seeing 0.5
inches of snow the further south and east into Kentucky with cities
such as Hazard and Pikeville seeing a 50-57% of seeing half an inch
of snow or more. In general, most of the area will see less than
half an inch of snow, with the greatest likelihood of half an inch
of more occurring across Pike an Letcher counties. Winds throughout
the day could be breezy at times, with westerly winds gusting to 20
mph.
Wednesday night through Thursday, the trough continues to lift off
to the north and east, leading to rising heights and quiet weather.
Thursday, expect any lingering morning clouds to decrease, leading
to mostly sunny skies in the afternoon. Highs will still be on the
chilly side, forecasted in the low to mid 30s. Some increasing clouds
can be expected form the south heading into the evening. Lows in
the lower 20s.
Friday, warm air advection will help drive temperates into the mid
to upper 40s, however, increasing clouds heading into the evening
are expected to result from an incoming weekend system. Lows Friday
night are forecasted in the lower 30s.
Saturday, a shortwave trough thats modeled to develop over Kansas
and Nebraska will pull moisture north from the Gulf of Mexico. As
the trough deepens, rain showers will begin over eastern Kentucky
during the afternoon. Showers look to continue at least into the
morning hours Sunday. Model discrepancy on timing lowers forecaster
confidence on onset and departure times. Highs each day are
forecasted in the low 50s, with lows in the upper 30s to near 40.
Monday, showers is modeled to move through eastern Kentucky as a
second shortwave trough brings another bought of showers to the
area. Highs are forecasted in the low to mid 50s, with lows in the
upper 30s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 1240 AM EST TUE DEC 10 2024
MVFR and IFR conditions will continue to overspread eastern Kentucky
from the southwest over the next several hours in association with a
warm frontal passage. This warm front will bring some fog ahead of
it, along with showers towards dawn, which will also overspread
the region from the southwest primarily beginning around 10Z and
lasting for several hours. This shower activity then continues
into the daytime hours. A few isolated thunderstorms are possible
in the afternoon hours, but confidence is too low to include any
mention in the TAFs, at this point. After 00Z Wednesday, an
approaching wave aloft will help usher in another round of
potentially IFR or lower conditions late in the period. Winds will
be light and variable into the morning hours before picking up
from the south by midday at around 5 kts. Look for a switch to
the northwest later in the evening at similar speeds.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CMC
SHORT TERM...HAL
LONG TERM...GINNICK
AVIATION...CMC/GREIF
Source:
JKL issues Area Forecast Discussion (AFD) at Dec 10, 12:40 AM EST---------------
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