JKL issues Area Forecast Discussion (AFD) at Dec 10, 5:29 PM EST876
FXUS63 KJKL 102229
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
529 PM EST Tue Dec 10 2024
.KEY MESSAGES...
- Rain redevelops tonight and transitions to a brief period of
snow on Wednesday morning before ending.
- Minor snow accumulations are expected Wednesday morning, most
notably at elevations above 2,000 feet.
- Snow showers, a few briefly heavy, could bring additional minor
snow accumulation Wednesday evening into Wednesday night.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 529 PM EST TUE DEC 10 2024
Regional radar mosaic shows a line of showers extending from
Inez to Hazard to Middlesboro at 22z. A MSLP/observations
analysis reveals that this line of convection is along a cold
front that is slowly sliding eastward through Coalfields. Ahead of
the boundary, temperatures range in the mid to upper 60s at lower
elevations while temperatures have dropped into the 50s behind
the boundary. A notable wind shift from southwest to northwest is
also noted with the boundary. This cold front extends southward
from an ~1008 mb low centered over far southeastern Ohio all the
way to the Mississippi River Delta. The front precedes a longwave
trough extending from the Central Canadian Arctic to northeast
Mexico. A potent vorticity lobe is found just east of the trough
axis from Illinois down the Central Texas. Further poleward within
the trough, an ~506 dam low is diving southward through Manitoba.
A secondary surface cold front is found ahead of this upper low
from near International Falls, MN to to over Nebraska and then
northwestward along the eastern slopes of the Northern Rockies.
The cold front presently crossing the area will shift off to the
east over the next couple of hours before becoming nearly
stationary. The associated showers will follows suit until
reaching the immediate vicinity of the Virginia border where they
are likely to train southwest to northeast through the evening.
Rainfall rates should be low enough to preclude any hydro issues.
Additional energy riding up the eastern side of the trough will
initiate a new surface low riding along the stalled front after
midnight, causing the precipitation shield to expand
northwestward over the Coalfields again through the wee hours of
Wednesday morning. Meanwhile, ongoing low-level CAA will push
temperatures downward through the night and into the mid 30s to
mid 40s, west-to-east, by around 5 AM EDT. Meanwhile, high
resolution models are showing a northeast-to-southwest oriented
band of snow developing over Indiana/Western Kentucky after
midnight due to zone of enhanced lifting/frontogenesis ahead of
the aforementioned vorticity lobe. That band is depicted as
generally broadening and intensifying as it moves eastward across
the Commonwealth and gains access to better moisture, eventually
merging with the precipitation shield over eastern Kentucky. As
the surface low passes to our east of the Appalachian Mountain
spine early Wednesday morning, cold air will rush in from the
west, drop temperatures into the lower to mid 30s, and flip rain
over to all snow between 5 AM and 9 AM EST. A brief period of
sleet is possible as the transition occurs, primarily east of the
Pottsville Escarpment. The snow continues light to moderate at
times before tapering off in the Lake Cumberland area as early as
7 AM EST, lingering as late as 12 PM EST over Pike County. The
warm antecedent ground and air temperatures should limit
accumulations to less than one half inch primarily on grassy and
elevated surfaces across a majority of the area. The area with the
best chances for impactful accumulation is from Martin down to
Bell County and eastward where the snow will persist the longest
and snowfall rates will be highest. In this area, up to around one
half inch of snow accumulation is forecast in valleys and up to 2
inches is possible at elevations above 2,000 feet (the higher
amounts may be enough for some instances of sloppy snow sticking
to highways). Once the snow ends, clouds are expected to break
partially and allow temperatures to warm back into the mid to
upper 30s at lower elevations during the afternoon.
As temperatures warm at the surface, cold air advection in the low-
levels ahead of the secondary cold front will lead to steepening
lapse rates Wednesday evening. Model soundings suggest that these
showers will have excellent access to the dendritic growth zone
which combined with moderately strong background flow could lead
to squall-like conditions in the heaviest activity. The equilibrium
level could flirt with -20C, perhaps even supporting enough
charge generation for a rumble of thunder in the most robust
updrafts. The snow showers wane to just a few flurries during the
late evening and early overnight as cold, dry air rushes in
behind the secondary front. Due to the showery nature of the
snowfall, accumulations could vary over short distances. The snow
showers could briefly coat pavement at some lower elevation
locales, but warm surface temperatures should tend to melt off
most of the snow that tries to accumulate. Grassy and elevated
surfaces should fare better, picking up to one half inch of new
accumulation in most cases. An isolated amount nearing an inch
cannot be ruled out. Temperatures are expected to fall into the
upper teens to mid 20s, northeast to southeast, by late Wednesday
night.
.LONG TERM...(Wednesday night through Monday)
Issued at 415 AM EST TUE DEC 10 2024
The extended portion of the forecast will start off quite active, as
a large and powerful low pressure system churns across the eastern
fourth of the nation Wednesday night and Thursday. Scattered snow
showers will be exiting the area Wednesday evening, as the trough
moves quickly off to the east of our area. Very cold air will
continue to spill into the region, as westerly flow persists behind
the departed storm system and cold high pressure settles over the
area. This ridging will remain in place to finish out the week,
leading to dry and warming weather for eastern Kentucky. According
to the latest runs of the GFS, ECMWF, and WPC model guidance,
another trough of low pressure will be moving our way heading into
the weekend. This system will be fast moving, and will bring quick
round of rain to the area over the weekend. After this system
departs the region late Sunday, the latest guidance has yet another
storm system moving in to begin the new work week. This low pressure
system will bring another bout of rain to eastern Kentucky to end
the period. The good news is, the passage of these last two storm
systems will lead to primarily southerly flow across our area, which
will allow temperatures to warm up nicely over the weekend and into
the first of next week. Highs each day from Friday onward should
average out in the upper 40s to mid 50s. We are not anticipating any
weather hazards for eastern Kentucky in the extended part of the
forecast at this time.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 156 PM EST TUE DEC 10 2024
Variable conditions were noted across the area at TAF issuance. A
few showers can be expected late this afternoon into early evening
with the passage of a cold front, warranting PROB 30 for showers.
Behind that boundary, low CIG (IFR or worse conditions) can be
expected for most of tonight. An uptick in precipitation follows
well after midnight as temperatures drop to near freezing,
transitioning the precipitation over to snow around and after
sunrise on Wednesday. Southwesterly winds up to around 10 kts
(with higher gusts) will turn northwesterly later this afternoon
and tonight.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GEERTSON
LONG TERM...AR
AVIATION...GEERTSON
Source:
JKL issues Area Forecast Discussion (AFD) at Dec 10, 5:29 PM EST---------------
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