JKL issues Area Forecast Discussion (AFD) at Dec 9, 4:15 AM EST597
FXUS63 KJKL 090915
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
415 AM EST Mon Dec 9 2024
.KEY MESSAGES...
- Temperatures remain above normal readings through Monday.
- Widespread rain at times will result in precipitation amounts
of 0.75 to 1.50 inches of rainfall through Wednesday.
- Rain likely changes to snow from late Tuesday night into
Wednesday evening. There is an increasing chance (5 percent in
southwest to 30-35 percent in the east and southeast) for minor
impacts Wednesday morning into Wednesday night.
&&
.UPDATE...
Issued at 1115 PM EST SUN DEC 8 2024
Utilized the latest 00z HREF and NBM 1-hour grids for PoP updates
through late afternoon and early evening Monday. This primarily
reduces PoPs during the daytime hours Monday as models get a
better handle on a dry slot and subsidence moving into the area
from the southwest and crossing the CWA, which will end the more
significant measurable precipitation a bit earlier Monday morning than
models were suggesting previously. Some drizzle or light shower
activity may remain into the day Monday, however.
UPDATE Issued at 817 PM EST SUN DEC 8 2024
Only minor updates needed for the early evening update. Rain is
moving into our southwest counties about as advertised with
respect to timing. Will continue to monitor trends and update as
needed. The late evening update will likely incorporate the 00z
model suite, though anticipate any changes to be minor.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 420 PM EST SUN DEC 8 2024
Late this afternoon, an upper level low was centered near the
OK/KS border with an associated shortwave trough south to TX with
the axis of shortwave ridging over the southeastern COnus to Lower
OH Valley region to western Great Lakes. A trough from eastern
Canada and into the Northeast/Maritimes was continuing to depart
further to the northeast while an upper level low was near the
MT/ND/Saskatchewan border with broad trough to the south into
portions of the northern Rockies and Northern Plains. At the
surface, a ridge high pressure extended from the western Atlantic
into the southeastern Conus while a sfc low was organizing near
the TX/LA border area and another sfc low was near the US/Canadian
border near the border area of Saskatchewan/Manitoba and ND with
a frontal zone extending into the Northern to Central Plains to
western Conus. In southwesterly flow, temperatures across south
central and eastern KY moderated well int the 50s to low 60 except
for the highest terrain locations above 3000 feet.
Tonight, the upper level low should trek into the mid MS Valley
and then the OH Valley and become an open wave. This shortwave
reaches the eastern Great Lakes to mid Atlantic by midday on
Monday and then the northeast during the afternoon to evening.
Southwest flow aloft will persist behind this system into Monday
night with an additional shortwave entering the OH Valley late in
the short term period in advance of a deepening mid and upper
level trough over the Central Conus. At the surface, a weak
reflection should track into the Lower OH Valley from the Lower MS
Valley tonight and weaken as it reaches the Commonwealth as the
shortwave trough shears out to the northeast. A deeper sfc low
will track from the Northern Plains/upper MS Valley and into the
Great Lakes tonight into Monday. The triple point should reach
Lake Huron on Monday evening while the trailing cold front nears
the Lower OH Valley to Southern Plains. As the next shortwave
trough approaches from the southwest, a sfc wave should ride
northeast along the boundary into the TN Valley region late in the
period.
Clouds will continue to thicken and lower this evening across
eastern KY as moisture increases substantially ahead of the
shortwave trough and sfc low approaching from the southwest. PW is
progged to increase from 0.6 to 0.8 inches at present to the 1 to
1.25 range around midnight tonight peaking int hat range ahead of
the shortwave before drier air works in later tonight and Monday
per the 12Z HREF with PW dropping to the 0.5 to 0.7 inch range at
that point. A relative lull in precipitation chances is
anticipated behind the departing shortwave by mid to late morning
Monday into Monday afternoon. As the sfc wave begins to develop to
the southwest and the next shortwave approaches, isolated to
scattered showers or patchy light rain may develop on Monday
evening, but better chances for widespread rain comes late as
moisture again increases Monday night with PW rising to the 0.7 to
0.9 range or so per the 12Z HREF. For the near term period
rainfall should generally average a half of an inch to an inch,
though some rain shadowed areas downwind of Pine Mtn in Letcher
into Pike County could pick up closer to a third of an inch per
some convective allowing model runs and 12 HREF PMM.
In southwest flow and in the warm sector to the south of the low
to the north and to the east of the trialing cold front/frontal
zone, eastern KY will remain mild through the period. Lows tonight
should only be in the 40s with highs on Monday again in the upper
50s to low 60s. Even milder lows in the mid to upper 40s are
anticipated on Monday night.
.LONG TERM...(Tuesday night through Sunday)
Issued at 415 AM EST MON DEC 9 2024
The extended period promises to start out in a very active pattern,
as an expansive and vigorous trough of low pressure is forecast to
be in place across almost the entire country. The apex of the trough
will likely be centered over the Great Plains and the Dakotas, and
will extend into the Pacific Northwest and New England. We will see
widespread cloud cover and rain showers across eastern Kentucky
Tuesday night, as a cold front moves through the region and winds
shift to the west. By early Wednesday morning, as winds shift to the
northwest and much colder air spills into the area behind the
departing trough, rain will mix with and eventually change over to
snow. The snow should be light in nature, and with ground
temperatures having warmed to begin the week, any accumulations
should be very light. After a couple of days with highs in the 50s
and 60s, a dramatic air mass change will occur mid-week. Highs
Wednesday and Thursday will only make it into the 30s and lower 40s
across our area. We should see another period of warming beginning
on Friday, as winds shift to the south ahead of another approaching
area of low pressure. Highs on Friday should rebound into the 40s,
with max values in the upper 40s and lower 50s on tap for Saturday
and Sunday, as southerly winds persist as another low pressure
system moves through.
As this system moves through the region, we will see another period
of rain across the area heading into and over the upcoming weekend.
This bout of rain should be relatively short lived and the rain
light. This second batch of precipitation should begin exiting the
area Sunday night, as low pressure again moves off to our east. In
spite of the possibility of accumulating snow to begin the period,
we anticipate no hazardous weather across eastern Kentucky in the
extended.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
ISSUED AT 1245 AM EST MON DEC 9 2024
MVFR, and at times IFR, conditions will continue to overspread the
area as rain moves across this part of the state through the
early overnight. A 2 to 3 hour period of moderate rain is likely
between 06 and 10Z at all TAF sites, at least intermittently.
Also, LLWS will be a threat from about 06Z to 12Z with rather
strong southwesterly winds aloft while sfc sustained winds
generally remain 10 KT or less, though some locations will see
turbulent mixing after 08Z resulting in gusty southwest winds
reaching the surface. Areas that see turbulent mixing may actually
mix out briefly and improve temporarily to VFR conditions during
the morning hours, but as winds diminish through the morning low
clouds (likely MVFR) and moisture will return and hold for much of
the remainder of the TAF period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CMC
SHORT TERM...JP
LONG TERM...AR
AVIATION...CMC/GREIF
Source:
JKL issues Area Forecast Discussion (AFD) at Dec 9, 4:15 AM EST---------------
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