014
FXUS63 KJKL 312350 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
750 PM EDT Fri May 31 2024

.KEY MESSAGES...

- Dry weather can be expected today and into Saturday. The next
  system will then begin to impact the region starting late
  Saturday and continuing into Sunday.

- It will become warmer and more humid with a potential of
  showers and thunderstorms continuing into the new work week.

&&

.UPDATE...
Issued at 735 PM EDT FRI MAY 31 2024

23Z sfc analysis shows high pressure off to the east and holding
on for one more evening over eastern Kentucky. Meanwhile, low
pressure continues to work towards eastern Kentucky from the west
with some leading high clouds moving into the area from central
Kentucky. Most of the fair weather cumulus has cleared out with
the approach of sunset. This will likely allow for a period of
decent radiational cooling yielding a moderate ridge to valley
temperature split through the night along with a potential for
fog in the river valleys late tonight into dawn, Saturday.
Currently temperatures vary from the upper 60s in some sheltered
eastern valleys to the low and mid 70s elsewhere. Meanwhile, amid
generally light and variable winds, dewpoints range from the mid
and upper 40s north to the low and mid 50s south. Have updated the
forecast mainly to add in the latest obs and trends for the
T/Td/Sky grids. These minor adjustments have been sent to the NDFD
and web servers.

UPDATE Issued at 1057 AM EDT FRI MAY 31 2024

The late morning update raises Sky grids through the short term
as high-level cloud cover is proving to be thicker than initially
forecast, enough so to partially obscure the sun. Besides raising
the sky cover in the grids, changes were minimal. Blended in
latest observations to the forecast.

UPDATE Issued at 703 AM EDT FRI MAY 31 2024

The forecast is on track. Early morning obs are blended into the
forecast without substantive changes.

&&

.SHORT TERM...(Today through Saturday)
Issued at 500 AM EDT FRI MAY 31 2024

Early this morning an upper level trough is centered along the
East Coast, ridging is over the upper Great Lakes and mid
Mississippi Valley, and a weak trough is to the west of that. At
the surface, high pressure is centered over OH. The setup is
bringing us our cool and dry weather.

The regime will shift east with time. This results in rising
geopotential heights and low level flow veering from easterly
today to southerly by Saturday. Abundant sunshine under the
arriving upper level ridge will bring a sizable warmup today. A
dry air mass still in place will allow for cool valley
temperatures in the 40s again tonight, but the return of low level
warm air advection will hold ridges milder. The upper level ridge
will slip to our east on Saturday and the weak trough will
approach while low level southerly flow advects moisture
northward. The GFS is faster to bring the moist flow and precip
eastward into our area compared to the ECMWF and NAM. A model
blend/compromise gives a slight chance of rain in our western
counties by late in the day Saturday. The GFS (wettest model)
shows stable soundings with its precip, while the NAM and ECMWF
are mainly dry until evening. Considering that, have not included
thunder during the day Saturday.

.LONG TERM...(Saturday night through Thursday)
Issued at 440 AM EDT FRI MAY 31 2024

Unfortunately this cooler and quiet spell of weather must come to an
end. By Saturday evening/night, the next weather system will begin
bearing down on eastern KY. High pressure and an upper level ridge
will be in place across JKL during the day Saturday, but by Saturday
evening, these will be exiting east of the state. This will allow a
shortwave to make its way into the Commonwealth starting in the
afternoon in the west, and slowly continue east throughout the
evening and overnight. This will be accompanied by a surface low
pressure system which will skirt north of the Ohio River Saturday
evening and night. Much of KY will find itself near the warm front,
with a surge of warm/moist SW flow ahead of the cold frontal
passage. This associated cold front should make it to eastern KY
by Sunday. Showers and thunderstorms are expected along and ahead
of this cold front, with pops moving in from the west and becoming
widespread overnight Saturday night, then continuing into Sunday
before exiting to the east by the afternoon/evening. Thankfully
this shortwave and surface system are not connected to a larger-
scale troughing pattern, so there isn`t going to be a clash in
airmasses and temperature. Therefore, don`t expect much in the way
of severe weather concerns (SPC is also not highlighting it at
this time), and shouldn`t see too much of a temperature drop
behind the departing cold front.

Rather, instead of a cooler airmass setting in, Monday actually gets
warmer as upper level ridging and high pressure set in briefly. The
NBM has temperatures rising well into the low and mid 80s across
eastern KY, some 10 degrees higher than the previous day in multiple
locations. Models are already starting to show disagreement in their
solutions from this point forward, especially when it comes to pops
affecting the region. Therefore, stuck with the NBM, which does
introduce mainly diurnally driven convection, peaking in the
afternoon and decreasing overnight. The better chance for pops may
come Wednesday and Wednesday night, as a large upper level low
tracks across the Canadian border, with an occluded surface low
pressure center and cold front which will make its way across the
state. Didn`t see any reason to deviate from NBM pops through the
extended given uncertainties, but do expect some changes in their
solutions as we get closer.

Temperatures should remain in the low to mid 80s through the
remainder of the period after Monday. Overnight lows are a bit more
interesting. The NBM shows some amount of cloud cover moving across
the region every night of the work week, though not completely
obscuring the sky. There is a lot of uncertainty here. Where and
when and how much these clouds set up will inevitably make an impact
on the overnight temperatures. And because there is chances of
convection just about every day, we won`t get the strong radiational
cooling like we would if we were sitting under strong high pressure
(subsidence) and clear skies. Did put in some ridge/valley
temperature differences, but didn`t go too crazy, since there may
still be quite a bit of variability. Generally expect temperatures
in the upper 50s and low 60s for Sunday night after the frontal
passage, and then in the 60s for the lows moving forward.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 750 PM EDT FRI MAY 31 2024

VFR conditions are expected through most of the period. The only
exception will be localized valley fog during the early morning
hours on Saturday, but the TAF sites will not be impacted. Light
and variable winds tonight will become southerly at 5 to 9 kts
after around 14Z. Look for some Lower clouds and shower chances
to start to move into the western aerodromes of KSME and KLOZ,
after 18Z.

&&

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

$$

UPDATE...GREIF
SHORT TERM...HAL
LONG TERM...JMW
AVIATION...CMC/GREIF