JKL issues Area Forecast Discussion (AFD) at Dec 15, 12:25 AM EST026
FXUS63 KJKL 150525 AAC
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1225 AM EST Sun Dec 15 2024
.KEY MESSAGES...
- Above normal temperatures persist through Wednesday.
- Periods of rain are forecast to impact the area at times tonight through
Wednesday night.
&&
.UPDATE...
Issued at 1105 PM EST SAT DEC 14 2024
After bottoming out in the upper 30s, the deeper sheltered valleys
have been experiencing temperatures climbing into the low 40s
over the past one to two hours as low levels clouds have
increased. These low clouds were increasing ahead of an initial
band of rain that has moved from central KY and into eastern KY.
This initial band will continue to move east over the next several
hours. Additional areas of rain or showers are upstream. Hourly
temperatures were updated based on recent observations as were
hourly pops to better align with radar trends.
UPDATE Issued at 725 PM EST SAT DEC 14 2024
In some areas, there have been breaks in the low clouds and deeper
valley locations in the east have managed to decouple per KY
Mesonet and home weather station networks. In these areas
temperatures have dropped into the upper 30s to low 40s. The low
clouds should increase over the next couple of hours and result in
temperatures in these locations rebounding by late this evening.
However, Min T and hourly T were adjusted to account for recent
observations.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 358 PM EST SAT DEC 14 2024
Thermometers across eastern Kentucky range in the 50s at most
places, though a few of the warmest places near Lake Cumberland have
breached the 60 degree mark including 61 degrees at the Monticello
Airport. Meanwhile, visible satellite has shown a general increase
and thickening in cloud cover from southwest to northeast ahead
of an ~1015 mb surface low pressure passing just south of the
Kansas City Metro.
This system, almost directly under its ~558 dam parent low, begins
to occlude as it presses eastward into Illinois tonight along a
lingering baroclinic zone. In advance, the system's warm conveyor
belt jet will spread eastward across the Commonwealth overnight
with PWATs surging to between ~0.8 to ~0.9 inch, as per the 14/12z
HREF. (Meager elevated instability may be sufficient to generate
an isolated lightning pulse; however, probabilities remain too low
to mention in the official forecast at this time.) On Sunday, the
surface low dissipates quickly in the morning as the parent upper
low moves more rapidly toward the Great Lakes and leaves the
surface reflection to be quashed under an incoming shortwave 500H
ridge. This shortwave ridging passes over the Ohio Valley Sunday
evening night, just in advance of the next Pacific 500H trough. A
surface cold front front associated with the aforementioned
surface low will stall over the Lower Ohio Valley on Sunday due to
a lack of upper level support. That lingering baroclinic zone
begins to lift back north and west on Sunday night as warm air
advection increases again ahead of the next upper level trough.
In more sensible terms, high clouds will thicken and lower this
evening from the southwest before a relatively steady rain develops
from west to east. Likely PoPs reach counties around Lake
Cumberland between 9 and 10 PM EST and spread eastward through
Pike County by 1 to 2 AM EST. Temperatures will be milder
overnight, mainly in the lower to middle 40s. Winds will also pick
up out of the southeast with gusts generally to around 10 to 20
mph, except over the mountaintops near the Virginia border where a
few gusts to 40+ mph cannot be ruled out. At the lower
elevations, the strongest gusts are anticipated before and when
the rain develops -- the gustiness should tend to subside
after precipitation onset due to the stabilizing effects of the
rainfall. Additionally, an isolated rumble of thunder cannot be
entirely ruled out. On Sunday, the steadier rain diminishes by the
midday hours, leaving just some light rain or drizzle at times
through the remainder of the day on into Monday night. Clouds
appear stubborn, so high temperatures are not expected to warm
much above 50 degrees in most spots. Another area of warm air
advection rainfall forecast to spread in from the west on Monday
morning, but devil is still in the details with regard timing.
Temperatures remain mild Sunday night with lows mainly in the mid
to upper 40s.
.LONG TERM...(Monday through Saturday)
Issued at 446 PM EST Sat Dec 14 2024
The long term forecast for Eastern Kentucky remains quite active
through the next week, with a series of frontal passages expected
during the work week and perhaps a clipper-type system next weekend.
Aloft, these features are supported by a progressively amplifying
pattern in which each passing trough gets deeper as upstream ridging
similarly builds stronger. Thus, the cumulative effects of these
systems are poised to leave the area in a cooler airmass by next
weekend, which could bring the forecast area its next chances of
wintery precipitation. Before then, however, the systems at the
start of the work week will yield above average temperatures and
repeated rain chances.
On Monday morning, the forecast area will be positioned firmly
within the warm sector of an occluded wave cyclone centered in the
Upper Midwest. Ahead of its parent trough aloft and behind a surface
warm front at the surface, persistent southerly to southwesterly
flow throughout the column will advect warm, moist air into the
region. The better dynamic and frontal lift approaches from the
northwest on Monday evening, so rain chances should ramp up
throughout the afternoon hours and then peak overnight. Guidance
continues to resolve the best instability with this system to our
west, so a widespread, soaking rain looks more likely than
thunderstorms. The highest rain totals will likely be across the
Bluegrass region and our northwestern CWA; this part of the forecast
area is closest to the best upper level ingredients for heavier
precipitation. Precipitation will linger the longest across our
southeastern counties into Tuesday morning, but guidance continues
to show the front's upper level support deamplifying quite quickly
overnight. While the front is expected to clear most of the area, it
is likely to stall out over the Tennessee Valley on Tuesday.
Uncertainty related to the exact positioning of said boundary has
kept slight chance PoPs near the Tennessee and Virginia state lines
on Tuesday, but most of the area should experience a clearing trend
as a surface high pressure system nudges in from the west. Tuesday's
temperatures will be slightly cooler than they were on Monday
(morning lows in the upper 40s and afternoon highs near 60), but the
lack of significant cold air advection will keep them seasonably
mild. The low temperatures on Tuesday morning will depend on one's
position relative to the front; it will be in the mid 40s ahead this
front and temperatures in the upper 30s immediately behind it.
However, the clearing trend throughout the day and the front's
weakening as it marches SE will allow temperatures to reach the low
50s area wide on Tuesday afternoon.
The aforementioned boundary is expected to lift back north across
the area again on Tuesday night in the form of a warm front. Further
upstream, the deepest of the week's troughs will approach the area
from the west, with flow backing towards the SW again. While
significant NBM spread in Wednesday's temperatures is noted, it is
plausible that afternoon highs could reach the 60s again. However,
the cold front with this third system should quickly sweep through
the area overnight, especially with the better upper level support.
With this FROPA will come another round of widespread rain chances,
but the bigger story will be the return of colder weather by the end
of the week. High temperatures will drop down into the 40s on
Thursday and Friday, with overnight lows dipping below freezing
again. Guidance has begun to pick up on the idea that a clipper-type
system could approach the area from the northwest next weekend, and
with the colder airmass in place, some light snow could materialize.
The specifics regarding any snow remain shrouded in typical long-
range uncertainty, so interests with pre-holiday travel concerns are
once again encouraged to pay close attention to the forecast as the
latest forecast data becomes available.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
ISSUED AT 1215 AM EST SUN DEC 15 2024
VFR conditions prevailed at TAF issuance as showers and low
clouds continue to spread east and northeast. Eventually the lower
levels are still expected to saturate enough for to MVFR ceilings
to develop in the west toward 12Z and across most of the area
through 18Z to include all the TAF sites. During that time, some
more western and northwestern areas should also experience a
period of IFR after 14Z, with a few hours of IFR forecast for
KSME, KLOZ, and KSYM. From 18Z on, a mixture of mainly MVFR and
IFR should then prevail even though showers should become more
scattered from west to east between 16Z and 22Z. Within the
steadier and heavier showers after 08Z, visibility will
be reduced to MVFR levels with times of IFR in some cases. Winds
will average southeast to south at generally less than 10KT
through 18Z, before becoming south at 10KT or less to end the
period. As winds just off the surface have increased ahead of the
approaching system, there is a threat of LLWS through 18Z for
portions of the region.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...GEERTSON
LONG TERM...MARCUS
AVIATION...JP
Source:
JKL issues Area Forecast Discussion (AFD) at Dec 15, 12:25 AM EST---------------
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