945
FXUS63 KJKL 101150 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
750 AM EDT Fri May 10 2024

.KEY MESSAGES...

- Some showers and perhaps a storm or two are possible, at times,
  through Saturday.

- Precipitation free weather is anticipated from  Saturday night
  into Monday morning, before unsettled weather returns.

- A cold front passing early this morning will usher in cooler
  temperatures through the weekend, with warming then returning.

&&

.UPDATE...
Issued at 735 AM EDT FRI MAY 10 2024

Just a quick update to the forecast mainly to add in some
sprinkles today and also include the latest obs and trends for the
T/Td grids. These minor adjustments have been sent to the NDFD
and web servers.

&&

.SHORT TERM...(Today through Saturday)
Issued at 525 AM EDT FRI MAY 10 2024

08Z sfc analysis shows eastern Kentucky still in the midst of
cyclonic flow from a low off the coast from Norfolk, VA. An upper
level disturbance is also moving through the area early this
morning helping drive a cold front into this part of the state.
This has periodically supported some light showers along it but is
now mainly noted by increased clouds along and north of itself,
as well as a wind shift and pick up from the north to northwest at
5 to 10 mph. Otherwise, temperatures are fairly uniform through
eastern Kentucky - generally in the upper 50s to lower 60s.
Meanwhile, dewpoints are running in the low to mid 50s with any
fog fleeting and limited to the deeper river valleys.

The models, and their individual ensemble suites, are in fairly
good agreement aloft through the short term portion of the
forecast. They all depict a trough finishing its push into
Kentucky this morning - dragging its core mid level energy
through during the afternoon. This then allows for a rebound in 5h
heights in its wake tonight before a second fast moving trough
descends into the northeast parts of the area for Saturday along
with limited height falls in northwest mid level flow - with an
uptick in energy as well. The model spread is fairly small with
these key features so the NBM was used as the starting point for
the short term grids along with the incorporation of the CAMs
details for PoPs and timing today and again on Saturday.

Sensible weather features slightly unsettled and cooler weather
through the first part of the weekend. The boundary passing
through the area this morning will keep a small chance of showers
or a thunderstorm in the picture through the afternoon before a
lull sets in during the upcoming night, though there probably will
be a better shot at seeing mainly river valley fog as the clouds
thin, or partially clear, for a time into Saturday morning. Then
another chance at some showers and a stray thunderstorm or two
arrives for Saturday afternoon with the latter feature aloft
brushing by to the northeast. The thunder chances appear to be
meager over much of the state with this, but in the east there
will likely be CAPE above 500 J/kg for a time along with a weaker
700 mb cap, though the lapse rates will be on the small side. As
such - do have a gradient of thunder potential west to east
through the JKL CWA on Saturday. Additionally, the thunder chances
(and PoPs) fade out quickly by dusk that evening.

The main adjustments to the NBM starting point consisted of adding
in some terrain details to the hourly temperatures and lows
tonight. As for PoPs - the NBM values were adjusted to include
some CAMs details for the limited potential of convection through
the afternoon and again on Saturday.

.LONG TERM...(Saturday night through Thursday)
Issued at 520 AM EDT FRI MAY 10 2024

An upper level low is expected to in place over the eastern Great
Lakes region as the period begins within an upper level trough
extending from near the James Bay region to the mid Atlantic states
to the southeast U.S. coast, shortwave ridging from the western
Gulf of Mexico to portions of the Central Plains, another upper
level low upstream near the southwest portion of Hudson Bay and
finally an an upper low over the Four Corners vicinity. Futher
west, the axis of an upper level ridge should be near the west
coast of the Conus. At the surface, one frontal zone is expected
to be well south from portions of the western Atlantic across
south FL and the Gulf of Mexico to the Lower Rio Grand Valley to
southern NM while a front is expected to be departing to the
south and east of the Lower OH Valley at that point. A ridge of
sfc high pressure should extend from the Lower MS Valley to the
Arklatex region to the western Great Lakes at that point as well.
Further northwest on Friday night, a wavy frontal zone is expected
to extend west near or north of the US/Canadian border from sfc
low pressure near the Manitoba and Ontario border.

Saturday night to Sunday night, the axis of the upper level trough
should shift east of OH Valley and Appalachians with height rises
and shortwave ridging building in to end the weekend. The axis of
the upper level ridge should extend from the eastern Gulf of
Mexico across the Southeast and Lower OH by late Sunday night.
Meanwhile, the upper level low west and southwest of Hudson Bay
initially should move to the far norther Ontario/souther end of
Hudson Bay/James Bay region and the upper low further southwest
should move from the Four Corners region to the Central Plains. As
this occurs, sc high pressure will build across the Southeast and
OH and TN Valley region and the central and southern Appalachians
Saturday night and Sunday before shifting toward the eastern
seaboard. To the west and southwest, lee cyclogenesis over the
Plains should occur in advance of the upper level low moving into
the Plains with a sfc low moving east near the KS and OK border
area Saturday night to Sunday night with the boundary initially
over the Gulf of Mexico lifting north toward the Gulf coast
downstream of the sfc low. Further north, low pressure will track
from the Ontario and Manitoba border vicinity to the James
Bay/Ontario/Quebec border area while the trailing frontal zone
drops into the western Great Lakes and upper MS Valley to Dakotas
to MT to a sfc low in Alberta and then trailing into the Pacific
Northwest. Locally, PW should drop under the influence of ridging
to to around 0.5 inches per LREF mean Saturday night/early Sunday
before gradually increasing toward 0.6 inches per LREF mean by
late Sunday night. With high pressure building in, the potential
will be there for small to moderate ridge/valley splits and
typical valley fog this time of year.

Monday to Tuesday night, the upper level low will move from the
Central Conus/Central Plains vicinity to the OH Valley and TN
Valley region and approach the Appalachians. Guidance is in good
agreement that a shortwave moves from the Arklatex region and
across the region Monday to Monday evening and perhaps another
Monday night to early Tuesday in southeast flow aloft. Well north
of the area upper level low should continue to meander near the
James Bay to the Ontario and Quebec border with a trailing
shortwave trough moving across the Great Lakes Monday to Monday
night. At the sfc, low pressure should track from the Central
Conus to the mid MS and Lower OH Valleys through Tuesday and then
toward the eastern seaboard on Tuesday night. Meanwhile the
shortwave crossing the Great Lakes should send the frontal zone
south and southeast of the Great Lakes and into the Northeast to
OH Valley to Central Conus as a sfc low mores to the Lower St
Lawrence Valley and Maritimes vicinity. Moisture will be
transported into the OH Valley and Appalachian region with PW per
the LREF mean climbing to about 1 to 1.2 inches by Monday evening
and peaking about 1.2 to 1.3 ahead of the boundary sagging into
the area Tuesday to Tuesday evening. After a dry start to the
long term period, unsettled weather will return by late Monday
into Monday night and continue into Tuesday night as one or more
shortwaves cross the area and sfc low pressure tracks into and
across the Commonwealth.

Wednesday to Thursday, the OH Valley/Appalachian region upper
level low/trough should gradually shift east to the eastern
seaboard with guidance suggesting that shortwave ridging quickly
shifts east across portions of the Southeast Conus, TN and OH
valleys and portions of the Appalachians to Great Lakes to end
the period ahead of the upper level troughing evolving from the
western Conus into the Central Conus with this trough axis
approaching the MS Valley toward the end of the period. A couple
of shortwaves could work into the OH and TN Valleys late in the
period once the ridge axis moves east. At the sfc, the frontal
zone should settle south of eastern KY and much of Southern
Appalachian region Wednesday night to Thursday with a ridge of
sfc high pressure shifting across the area Wednesday to Wednesday
night. Further west, low pressure should evolve over the Central
Conus/Plains and approach the MS Valley on Thursday. PW over the
region should briefly drop below 1 inch under the influence of
ridging behind the sagging front before increasing again on
Thursday about 1 to 1.2 inches per LREF mean. A brief lull in
chances for precipitation should occur by late Wednesday into
Wednesday night and perhaps linger into early Thursday. Chances
will however increase as the ridge shifts east and the next
series of disturbances and low pressure system approaches to end
the period.

Temperatures begin the period below normal, before climbing to
around 5 degrees above normal on Monday with high pressure
dominating. Nearer to normal high temperatures are expected with
more in the way of clouds for Tuesday to Wednesday. Temperatures
may climb to nearly 5 degrees above normal to end the period ahead
of the next approaching series of systems on Thursday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
ISSUED AT 750 AM EDT FRI MAY 10 2024

A cold front moves through the area this morning and into the
afternoon. This passage will mean a time of MVFR, and briefly
IFR, CIGs to the terminals of eastern Kentucky. In addition, some
isolated to scattered shower activity will be around through 18Z
with the odd chance of a thunderstorm too low to include in any
individual TAF site at this point. CIGs then improve to VFR by
mid-afternoon as the system begins to depart to the east. Any fog
late tonight is expected to stay confined to the valleys and leave
visibilities unmarred at the TAF sites. Light winds this morning
will become northwesterly and increases to around 10 kts during
the day, on account of that front settling through the region.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...GREIF
SHORT TERM...GREIF
LONG TERM...JP
AVIATION...GREIF