309
FXUS63 KJKL 030345 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1145 PM EDT Thu May 2 2024

.KEY MESSAGES...

- Shower and thunderstorm chances return to the forecast Friday
  through Wednesday.

- Cooler this weekend, though temperatures remaining above normal
  by 5 to 10 degrees on average from the weekend well into next
  week.

&&

.UPDATE...
Issued at 1145 PM EDT THU MAY 2 2024

No significant changes to the forecast with just the inclusion of
the latest obs and trends for the T/Td/Sky grids with this update.
These minor adjustments have been sent to the NDFD and web
servers along with a freshening of zones and SAFs.

UPDATE Issued at 750 PM EDT THU MAY 2 2024

23Z sfc analysis shows weak high pressure holding on over eastern
Kentucky for one last evening as low pressure is advancing from
the west. This pressure pattern helped push temperatures to
record and near record highs on account of mostly sunny skies. Now
the readings are only slowly backing down - ranging from the mid
70s to lower 80s. Meanwhile, amid light west to southwest winds,
dewpoints are holding in the mid 50s to lower 60s most spots. Have
mainly updated the forecast to include the latest obs and trends
for the T/Td/Sky grids. These minor adjustments have been sent to
the NDFD and web servers.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 322 PM EDT THU MAY 2 2024

Upper ridging and surface high pressure remain the dominant weather
features this afternoon, but this will begin to slowly change
through the short term period.

Mid-latitude cyclonic jet stream remains well northwest of the
region from the Central Plains to the Upper Great Lakes region, and
will remain that way through Saturday night. Meanwhile, stout and
persistent upper ridging will begin to slide slowly east and weaken
as persistent weak shortwaves move from the Southern Plains to the
Mid-Atlantic region through Saturday night.

A pronounced shortwave currently over the Arklatex region will move
toward the area tonight, bringing increasing cloud cover, with
shower chances toward dawn west and southwest of Somerset. Big
question mark is how much does the increasing cloud cover impact
tonight`s low temperatures. Overall, the trend in forecast lows
tonight is warmer given the warm air and moisture advection into the
region, but COOP MOS still suggests lower to mid 50s for a lot of
the sheltered eastern valleys. Decided to stick close to the NBM
with primarily 60s outside the sheltered valleys, with local effects
in the typically cooler areas given the uncertainty, though this is
still a much warmer forecast than the previous shift.

Showers increase through the morning from west to east, with
thunderstorms becoming more likely from late morning into the
afternoon especially for western and southwestern areas as
instability increases. This will introduce a continuous period of
high-end chance to categorical (i.e., 50 to 90 PoPs) Friday
afternoon into Friday evening decreasing to high-end chance to low-
end likely (50 to 60) PoPs Saturday morning.

The warmest locations in our CWA will be toward Pike County Friday
as this area will remain closer to the downstream ridging plus have
a bit of downslope drying from light southerly flow. Highs in this
area may reach well into the 80s, while highs trail off to the upper
70s across western parts of the CWA where more persistent shower and
thunderstorm activity is expected. By Friday night, PoPs will be
more uniform across the area, which will yield lows in the mid 50s
to 60s.

.LONG TERM...(Saturday through Thursday)
Issued at 322 PM EDT THU MAY 2 2024

The period is expected to begin with an upper level ridge extending
from the Bahamas into the Northeast Conus, an upper level low just
south of Hudson Bay in northern Ontario with a shortwave trough
trailing into the Upper MS to portions of the northern to central
Plains. Additional weaker shortwaves should extend from the
Central Plains to the Ozarks and another moving through the OH
Valley to southern Appalachian region. Further west, another upper
level low will be nearing the Northwest Conus with weak ridging
in between this feature and trough that extending into the Central
Conus. Meanwhile, a wavy frontal zone is expected to extend into
the Lower OH Valley from low pressure over the eastern Great Lakes
as the period begins with another sfc low southwest of Hudson Bay
south to the upper MS Valley to the southern Plain to
southwestern Conus.

Saturday to Sunday night, the axis of the upper level ridge
initially near the east coast will shift east into the western
Atlantic while the upper level low initially centered in the
vicinity of the southwest portion of Hudson Bay moves to Quebec.
Meanwhile, the shortwave initially tracking across the Lower OH
Valley and southern Appalachians should shift east of the area
with another shortwave moving across the Lower OH Valley late Sat
night into Sunday and another perhaps stronger shortwave that will
have moved across the Southern Plains and Ozark vicinity should
near the Lower OH Valley by late Sunday night. Further west, the
upper level low initially near the Northwest Conus is expected to
move across the western Conus/Great Basin and begin to weaken/open
up as it near the Rockies Sunday night. At the sfc, the first
wavy front zone is expected to cross eastern KY to begin the
weekend, with the next boundary moving to the Central Great Lakes
to Lower OH Valley to Southern Plains during that time as well.
However, this boundary should tend to slow down and stall as it
nears the OH Valley while the the western to northwest extent of
this becomes warm front into eastern MT. Chances for convection
should be highest on Saturday with the first passing wave and
boundary with secondary peaks in convection possible with daytime
heating on Sunday and perhaps late Sunday night ahead of a
shortwave approaching form the southeast.

Monday to Tuesday night, the consensus of the guidance is for a 500
mb shortwave trough to cross the OH Valley region Monday to Monday
evening followed by shortwave rigging moving form the MS and across
the Great Lakes to OH Valley and Appalachians on Tuesday. Meanwhile,
the upper level low moves across portions of the Rockies and into
portions of the northern Plains and an upper level trough
encompasses much of the Western to Central Conus. At the sfc, a wavy
boundary that may initially be stalled out near the OH River is
expected to lift north as a warm front as warm front into the Great
Lakes east of the sfc low as guidance suggest it moves east near the
US/Canadian border to the upper MS Valley while a triple point low
may reach the western Great Lakes with the trailing front should
track across the Plains/portions of the Central Conus to the western
Great Lakes to mid MS Valley to Southern Plains. A rather warm and
moist airmass should be across the region, with passing weak
shortwaves and diurnal heating leading to peaks in chances for
convection each afternoon and evening with confidence greater on a
peak during Monday with a passing shortwave.

Wednesday to Thursday, the axis of the shortwave ridge is
generally expected to shift east and southeast to a position from
the Gulf of Mexico to parts of the western Atlantic with
southwest flow from the Southwest Conus across the Plains/Central
Conus into the OH Valley region, Southeast and Appalachians
downstream of rather broad troughing. Multiple weak shortwaves
could move from the Plains across the OH Valley/Southeast and
across the Commonwealth during this time. Meanwhile, the sfc low
well to the north of the Commonwealth should move gradually from
the Great Lakes toward portions of the Great Lakes to mid Atlantic
with the trailing frontal zone shearing from northeast to
southwest and perhaps stalling or nearly stalling from the OH
Valley to the Southern Plains regions. This boundary should
interact with the passing shortwaves and heating each day with a
diurnal peak in chances for convection each afternoon and evening.

Temperatures will begin the period about 5 degrees above normal on
Saturday even after the possible passage of the rather weak front.
Then, from Monday to Thursday, the region will be in the warm sector
much of the time with temperatures likely to be above normal by
around 5 to 10 degrees above normal

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 800 PM EDT THU MAY 2 2024

VFR conditions continue under mostly clear skies. Later this
evening high BKN to OVC skies spread in over the area, west to
east. An area of showers with a few thunderstorms then approach
western TAF sites from the after 12Z Friday. Have kept VCSH into
the TAFs at various times between 12 and 18Z Fri, with more
continuing into the afternoon further east, but these will likely
be further refined as we get a better handle on timing, as well
as whether a mention of CB and VCTS will be warranted. Winds will
be light and variable overnight then favor the south to southwest
at 5 to 10 kts throughout the day, Friday.

&&

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

$$

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