460
FXUS63 KJKL 051455 AAC
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1055 AM EDT Wed Jun 5 2024

.KEY MESSAGES...

- Showers and thunderstorms will affect the area today and
  tonight.

- Relatively cooler and drier weather will arrive behind a cold
  front passing through eastern Kentucky on Thursday.

&&

.UPDATE...
Issued at 1055 AM EDT WED JUN 5 2024

Convection, mainly just showers continue to move northeast across
the region in association with a lead disturbance shortwave
trough moving across the Commonwealth and the TN Valley and ahead
of the main 500 mb trough which is nearing the Lower OH Valley.
Lightning activity has been minimal so far, though as we approach
peak heating, lightning will be commonplace. Due to persistent
clouds, CAPE is lower today as compared to yesterday with shear
still lower end, but about 5KT higher than yesterday, nearer to or
just above 20KT. Moisture is quite substantial, with PW analyzed
in the 1.4 to 1.7 inch range. Although a strong storm or two
cannot be ruled out with a gusty wind threat, locally heavy rain
is the main threat in any areas that pick up multiple
thunderstorms following the rainfall that fell yesterday.

UPDATE Issued at 818 AM EDT WED JUN 5 2024

Adjusted cloud cover for tonight to slow down the decrease in
clouds, as a blend of overnight model runs suggests clouds will
be slower to leave.

&&

.SHORT TERM...(Today through Thursday)
Issued at 557 AM EDT WED JUN 5 2024

A strong upper low (by June standards) will move east southeast
from Saskatchewan to the upper Great Lakes during the period. An
elongated trough/wave rotating around the south side of the low
was roughly over the Mississippi Valley early this morning, and
will approach our area today and depart to our east tonight. It
will support a weak surface cold front accompanying it. The
approach of the front and upper trough will support showers and
thunderstorms in the warm and moist air present over our area
today into tonight. Precipitation will diminish as the front and
upper trough depart tonight and early Thursday. Models disagree on
how much drying takes place initially behind the front. The
greatest amount of drying will be behind a secondary front which
will be entering the forecast area from the northwest Thursday
evening. Before that happens, models suggest some additional
shower develop on Thursday afternoon as the second front
approaches. Forecast soundings show shallow instability capped in
the mid levels-- convective currents not tall enough for thunder,
but deep enough for precip. As mentioned, there is still some
variance in models regarding the setup ahead of the second front,
and the GFS and HRRR are the most aggressive at generating light
precipitation. Have used a 20% late day POP at this time.

.LONG TERM...(Thursday night through Tuesday)
Issued at 350 AM EDT WED JUN 5 2024

The 05/00z model suite is generally in good synoptic agreement at
the start of the period before spread increases this weekend/early
next week. Initially, an ~548 dam low is in place over the Upper
Great Lakes, embedded within a swale extending northwestward in
the Yukon. This relative troughing is sandwiched between a
prominent ridge over the western CONUS and another orphaned ridge
axis aligned from Labrador/Quebec northwestward into the eastern
Beaufort Sea. At the surface, a regional analysis shows an ~991 mb
low south of James Bay while its cold front extends southward in
to the Central Appalachians and then extends southwestward along
the southern side of the of Ohio River, including across Kentucky,
and beyond across the Ozarks. High pressure is found just north
of the boundary across the the Central and Northern Plains.

The cold front sags across southeast Kentucky late Thursday
evening as the parent upper low drifts toward the Lower Great
Lakes. The upper level forcing with this system remains well
north of of the Commonwealth, leaving just the weak low-level
convergence along the front to spark convection under a strong
~600 mb cap. The potential for lingering scattered convection is
depicted by a majority of the 00z CAMs suite. Once that front
clears the area, a drier and cooler air mass will move in on
northwesterly breezes late Thursday Night and Friday as surface
high pressure sinks southeastward into the Tennessee Valley/Mid-
South Saturday night. Meanwhile, a vort max over the Canadian
Prairies, will pivot, either in part or whole, around the upper
low over the Lower Great Lakes, bringing another surface cold
front to the Eastern Kentucky Coalfields. The system`s evolution
will have a significant bearing on the rain chances late this
weekend and early next week, depending upon whether this vort max
remains more of a progressive open wave or forms a slow-moving
closed low.

Sensible weather will feature a diminishing threat for showers on
Thursday evening. Once the precipitation ends, fair weather can
be expected into Saturday morning with slightly cooler temperatures,
ranging mainly in the mid to upper 70s for highs and in the lower
to mid 50s for lows. A few of the coldest hollows could see upper
40s on Friday night. While the specifics are still uncertain, the
daily threat for showers and even a few thunderstorms is very
likely to return on Saturday and persist into early next week as
the next cold front and upper level system approach. Forecast
high temperatures generally range from the mid to upper 70s
through the remainder of the forecast period while nighttime lows
bottom out in the mid to upper 50s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
ISSUED AT 818 AM EDT WED JUN 5 2024

Mainly dry weather was present to start the period. Conditions
were largely VFR, with the exception of a few places near the TN
border. A period of MVFR ceilings may occur this morning as
heating begins, but the bulk of the day into tonight is forecast
to be VFR, aside from any showers and thunderstorms which occur.
There are showers and thunderstorms expected at times, mainly from
mid day into tonight. However, the predictability of timing at
any given location is too low to specify it in the TAFs, and VCTS
has been used.

&&

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

$$

UPDATE...JP
SHORT TERM...HAL
LONG TERM...GEERTSON
AVIATION...HAL