858
FXUS63 KJKL 051802
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
202 PM EDT Sun May 5 2024

.KEY MESSAGES...

- Shower and thunderstorm potential lasts through the next 7
  days.

- Above normal temperatures are forecast through Thursday. A cold
  front should pass late in the week and bring readings down to
  near or below normal.

&&

.UPDATE...
Issued at 1257 PM EDT SUN MAY 5 2024

Just issued a fairly extensive update to the short-term grids that
will likely constitute most of the changes to the afternoon
package. Given shower and thunderstorm activity developing raised
1-hour PoPs to a minimum of 15 for the entire area for the next
few hours. Other updates will be addressed with the afternoon
package, but generally not much change to the overall thinking
from the previous short-term discussion below.

UPDATE Issued at 1101 AM EDT SUN MAY 5 2024

The late morning update is out. Generally lowered PoPs somewhat
based on a lack of forcing for ascent for shower and thunderstorm
development through this evening. A weak stationary surface front
draped across the area will help trigger some activity, but rising
heights aloft will make more widespread activity difficult.
Otherwise, just blended in latest observed trends to the forecast.

UPDATE Issued at 700 AM EDT SUN MAY 5 2024

Made some adjustments to this mornings hourly forecast grids
using recent obs. This revealed that low temperatures at a number
of locations across eastern Kentucky were running at least a few
degrees cooler than forecast. Based on current trends, adjusted
this mornings lows to match the obs. The updated grids have been
saved, published, and sent to NDFD and remote web servers.

&&

.SHORT TERM...(Today through Monday)
Issued at 456 AM EDT SUN MAY 5 2024

Active weather expected across eastern Kentucky heading into the new
work week, as a weak cold front and wave of low pressure move
through the region. Isolated to scattered storms are expected to
move through the area today, especially this afternoon into early
this evening, during peak heating, and when instability will be
maximized. A weak cold front will be the trigger for showers and
storms today, but should only provide enough lift to support
isolated to scattered convection, in spite of the moisture and
instability that will be in place. After the first round of rain
ends this evening, another round of more widespread and robust
showers and storms will begin moving into our southwest counties
very late tonight into early Monday morning. This second wave of
rain will be in response to a wave of low pressure that forms along
a slow moving cold front to our southwest. As this low moves over
our area on Monday, it will allow numerous showers and scattered
storms to fire during peak heating Monday afternoon.

The higher resolution models are all showing similar solutions
supporting only isolated to scattered convection at best, so today`s
forecast was based on that data. The NAMNEST, RAP, NAM12, and HRRR
were all in pretty good agreement on the extent of todays showers
and storms. However, considering how unstable and moist the
atmosphere will be today, decided to lean more toward scattered
activity than isolated in spite of the models output. Rain chances
on Monday should be much better since a stronger system will be
moving through, and the atmosphere will still be quite moist and
unstable. Locally heavy rainfall will be possible at times on
Monday with any thunderstorms.

Temperatures will continue to average well above normal today and
Monday, with highs in the upper 70s to lower 80s on tap. Winds
should be out of the southwest at 5 to 10 mph today and tomorrow,
and light and variable again tonight.

.LONG TERM...(Monday night through Saturday)
Issued at 456 AM EDT SUN MAY 5 2024

A persistent wet weather pattern will continue in place through
the first part of the long term forecast. Generalized west
southwest flow in the mid/upper levels will overlie low level
south southwest flow off the Gulf of Mexico. A stalled frontal
boundary is forecast to be near the Ohio River Monday evening as a
shortwave trough aloft departs to the east. The front is expected
to shift north Monday night, then back south into KY by Wednesday
morning as another shortwave trough aloft tracks by, then back
north again Wednesday night. The front will finally make a strong
push southeast through our area late in the week as a more
substantial mid/upper level trough drops southeast over the
eastern CONUS. Models are coming into better agreement for a cold
frontal passage on Thursday. The presence of the frontal boundary
along with the shortwave troughs should support multiple rounds
of showers/thunderstorms, with likely POPs now in the forecast
each period from Monday night through Wednesday night area wide.
Precip may linger into Thursday, but there is some model variation
concerning the arrival of drier mid/upper level air wrapping into
a deepening storm system passing to our north on Thursday. This
drier air aloft will be fleeting, as the upper level trough drops
into the eastern CONUS. The much colder air aloft associated with
the trough should still allow for scattered showers/thunderstorms
to bubble up at times even after cold fropa as we move into the
weekend. Specific timing of impulses enhancing this activity
remains problematic at that long time range.

Our relatively weak flow aloft presently should strengthen by
Tuesday. The increasing shear will be more supportive of organized
convection, with a resulting severe thunderstorm risk beginning
on Tuesday and lasting until our last round of convection before
cold fropa.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
ISSUED AT 202 PM EDT SUN MAY 5 2024

VFR conditions are expected into this evening outside of brief
MVFR/IFR conditions in isolated to scattered showers and
thunderstorms. There are model discrepancies late tonight into
Monday which makes forecasting a bit difficult, depending on the
arrival of the next disturbance. Some models depict showers and
then thunderstorms moving in late in the overnight through Monday
morning, while other models depict partial clearing overnight
which would allow widespread fog formation during the few hours
straddling dawn, before the next round of showers and
thunderstorms move into the area after 12z-15z Monday. For now,
decided to split the difference, with future forecasts likely
being able to hedge more one way or the other with increasing
clarity on which scenario becomes more likely. At any rate, expect
widespread MVFR and possibly IFR/LIFR cigs and/or visibility after
06z through 13-14z Monday before beginning to gradually improve
through the end of the TAF period.

&&

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

$$

UPDATE...CMC
SHORT TERM...AR
LONG TERM...HAL
AVIATION...CMC