JKL issues Area Forecast Discussion (AFD) at Nov 6, 7:08 AM EST698
FXUS63 KJKL 061208 AAA
AFDJKL
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
708 AM EST Wed Nov 6 2024
.KEY MESSAGES...
- Above normal temperatures are expected through the upcoming
week.
- Widespread measurable rainfall is expected through Thursday,
with rainfall totals of about three quarters of an inch possible
over our Bluegrass, to as little as a tenth of an inch of
rainfall along the KY-TN-VA state line.
- A better chance of widespread rain and higher rainfall totals is
possible during the upcoming weekend and into early next week.
&&
.UPDATE...
Issued at 708 AM EST WED NOV 6 2024
A cold front is moving eastward across the Commonwealth this
morning, roughly located from KCVG southwest to KHOP and then
KMKL. A wide swath of light to moderate rain showers is pushing
eastward as well. There was a few lightning strikes that showed
up further west through the overnight, but that has died off over
the past couple to few hours. This frontal boundary will slow as
it progresses eastward, making timing of convection into the
eastern Kentucky the primary challenge. Showers have overspread
our Bluegrass counties and will continue to do so much of the
day. Locations south of the I-64 corridor will probably not be
impacted until later this morning or even late this afternoon or
evening for our far southeast. Again, a few thunderstorms can not
be ruled out, but threat appears minimal. No update to the zones
planned at this time. Updated grids have been issued.
&&
.SHORT TERM...(Today through Thursday)
Issued at 512 AM EST WED NOV 6 2024
There is a slight pattern change aloft through the short term.
Four Corners H500 low fills a bit, with heights rising about 800m.
This low also digs southward, becoming increasingly cut off from
the main core of westerlies that transition into a more zonal flow
pattern roughly along the Northern Tier. Shortwave trough
tracking through the core westerlies in Canada flattens the ridge
that has been in place over the southeast portions of the US. As a
result, flow across the Commonwealth shifts from southwest to
west, which should open the door and allow systems to move further
south, i.e. more readily into and/or through the Ohio Valley
through the period. At the surface, a surface cold front moves
from the Mississippi River Valley east and southward into the
Upper Ohio and Tennessee valleys. Based on the 0Z cycle suite,
this front, or frontal zone manages to drop into eastern Kentucky
before stalling our across our area.
Sensible weather features an unsettled short term, with an
increasing likelihood of measurable rainfall across much of the
area with time. A zone, or band of greatest PoPs (80%) are found
across our northwestern zones, or Bluegrass counties today, with a
tight gradient to lower PoPs (30%) across the southeast along the
KY/VA state line. As the surface front edges into the
Commonwealth, becoming more west-east oriented with time, the core
of greater PoPs shifts south and east, so that even central and
southern potions of the forecast area will see at least a good
chance of rain (50% or higher) through the short term
window...tonight and Thursday. Total rainfall expected through the
short term will range from close to three quarters of an inch
over our Bluegrass, to as little as a tenth of an inch of rainfall
across our southern most zones. At least most of the area is
expected to see a wetting of much needed rainfall.
Continued to carry thunderstorms in the forecast, mainly for
consistency and because SPC maintains a general thunder over
portions of eastern Kentucky during the short term. However,
instability is marginal at best and feel the overall chance of
seeing thunderstorms remains low at best. Overall, NBM
probabilities for thunder continue to appear too high. Ensemble
solutions and probabilistic guidance suggest the atmosphere
struggles to generate enough environmental instability (CAPE of
around 500 J/kg or less on average) to warrant anything more than
a 20-30% chance of thunder through the period.
.LONG TERM...(Thursday night through Tuesday)
Issued at 518 AM EST WED NOV 6 2024
The period is expected to begin with an upper level ridge centered
over portions of the western Atlantic from the Bahamas to south of
Bermuda with shortwave ridging centered over the TN Valley to the
mid MS Valley. Broad troughing is expected to be in place to the
north over much of central to eastern Canada while an upper level
low should be in place to the south of the Four Corners region with
upper level ridging extending from the eastern Pacific into portions
of the western Conus. At the sfc, a ridge of high pressure is
expected to extend from the Central Plains parts of the MO Valley to
the mid MS Valley to the eastern Great Lakes. Rafael is expected to
be west of FL and northwest of Cuba in the eastern Gulf of Mexico
while a wavy frontal zone should be gradually sagging south from the
mid Atlantic states to VA an WV to eastern KY to middle TN to the
TX hill country to northern portions of Mexico.
Thursday night through Friday night, the axis of an upper level
ridge should shift east to the mid MS Valley and the Lower oH Valley
and Southern Appalachians with the axis of this ridging nearing
eastern KY late Friday night. Meanwhile, Rafael should move into the
central portions of the Gulf of Mexico while the upper low initially
located south of the Four Corners region should work northeast to
the western KS/eastern CO to OK panhandle region. This will occur as
upper level ridging shifts further east across parts of the western
Conus and an upper level trough nears the west coast of the Conus.
At the surface, the wavy frontal zone/cold front should gradually
sag southeast of the Commonwealth and to the deep south as Rafael
continues to track west north west in the Gulf of Mexico and sfc low
pressure treks from the southern Plains to western KS. Further
north and east, sfc high pressure should work across the western to
central Great Lakes and Lower OH Valley to the eastern Great Lakes
to the Carolinas. In this scenario, any lingering showers should
diminish quickly by late Thu evening and give way to a potential
moderate ridge/valley split and some areas of fog in the valleys.
Another ridge/valley split is favored under the synoptic patter for
Fri night as well with some valley fog possible as well though it
should be more confined to the deeper valleys along the larger
waterways.
Saturday to Sunday night, the upper level ridge axis will shift east
and northeast of the Commonwealth and allow the upper level low to
track north northeast to norther IA/southern MN and then into the
western and northern Great Lakes to Ontario while ridging builds
east from the western Conus into portions of the Plains/central
Conus in its wake. Sfc low pressure meanwhile should track to the
Dakotas/upper MS valley and then across the northern Great Lakes to
Ontario. The boundary that will have sagged south of the area to
begin the long term period should lift into the Lower OH Valley Sat
night to early Sunday and then northeast of eastern KY Sunday to
Sunday evening while the cold front associated with the low moves
across the western to central Great Lakes to the eastern Great Lakes
and sags to near or just southeast of the OH River. Per the 00Z
LREF, PW should initially be int he 0.4 to 0.7 inch range early on
Saturday, but should climb to the 0.9 to 1.3 inch range on Sat
evening and then rise to as high as the 1.2 to 1.5 range by midday
to early afternoon on Sunday. This increased moisture and the warm
front lifting across eastern KY followed by the approach of the cold
front and height falls late Sat night into Sun night should
result in showers. Instability will be limited, but some thunder
could occur on Sunday and Sunday night ahead of the cold front.
Some decent rainfall rates will be possible, but the region has
also been quite dry so far this month and over the past few weeks
and is currently in Do/Abnormally dry drought status. This should
greatly limit any hydro concerns.
Monday to Tuesday, the upper level low is progged to move into
Quebec and the St Lawrence Valley and Northeast Monday to Monday
night and then begin to merge with a trough moving from central into
eastern Canada. The cold front should continue sagging across the
area on Monday and Monday night as sfc high pressure builds into the
Appalachians in advance of upper level ridging working from the
Plains to MS Valley and into the eastern Conus. This will lead to
gradually decreasing chances for showers fro eastern KY as deeper
moisture departs to the east and southeast and drier air moves in to
end the period.
Temperatures should remain above normal during the long term period
even behind the first cold front early in the period and the second
early next week. Departures should generally average 5 to 10 degrees
above normal through the period.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
ISSUED AT 708 AM EST WED NOV 6 2024
A cold front is moving eastward across the Commonwealth this
morning, roughly located from KCVG southwest to KHOP and then
KMKL. A wide swath of light to moderate rain showers is pushing
eastward as well. This front will slow as it progresses eastward,
making timing of convection into the area the primary challenge
of the forecast. Showers will impact KSYM much of the day, with
terminals further east being impacted later this morning or for
KSJS probably late this afternoon. A few thunderstorms can not be
ruled out. However, based on minimal instability at best across
the area, felt storms were unlikely enough to leave any mention
out of the TAFs for now. Southwest gradient winds will subside
through the day, especially once shower activity arrives. As the
cold front settled down across eastern Kentucky and stalls, lower
CIGS and VSBYS become a concern through the overnight period,
dropping into IFR/LIFR territory.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...RAY
SHORT TERM...RAY
LONG TERM...JP
AVIATION...RAY
Source:
JKL issues Area Forecast Discussion (AFD) at Nov 6, 7:08 AM EST---------------
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