797
FXUS63 KJKL 061956
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
356 PM EDT Mon May 6 2024

.KEY MESSAGES...

- Our main shower and thunderstorm potential lasts through
  Thursday, with a smaller possibility at times through the
  weekend.

- Severe thunderstorms are possible Tuesday through Wednesday
  night. Large hail and damaging winds are the primary threats,
  but there is also a small risk of tornadoes. Locally heavy
  rainfall could also lead to flooding.

- Above normal temperatures are forecast through Thursday. A cold
  front should pass late in the week and turn temperatures below
  normal through the weekend.

&&

.UPDATE...
Issued at 1258 PM EDT MON MAY 6 2024

Did several updates throughout the morning, first to freshen up
the temps/dew points/winds based on the latest observations, and
then to update the pops/weather based on the latest trends.
Overall precip is likely throughout the day, but there were 2
defined lines that went through this morning. We may have a bit of
a break for an hour or two before the next round of precip moves
in and develops in the afternoon. Will continue to monitor the
radar and make updates as needed. All updates have been published
and sent to NDFD/web.

UPDATE Issued at 700 AM EDT MON MAY 6 2024

Did a quick update of this morning`s low temperatures. Based on
recent obs, it appears that no appreciable ridge valley split
occurred overnight or early this morning, so the morning lows
needed to be refreshed to match current trends with lows being
warmer by a couple of degrees at a number of locations. Also used
the latest obs to freshen up the rest of the hourly forecast
grids(dewpoints, RH, winds, etc). Lastly, made a few minor tweaks
to the precip probability grids between 9 and 12Z this morning,
but this should not affect the existing zone forecast text
product.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 521 AM EDT MON MAY 6 2024

Active weather expected across eastern Kentucky to kick off the
new work week. Showers and storms will become quite numerous today
and tomorrow, especially during the afternoon and evening periods
during peak heating and when instability will be maximized. The
triggers for convection the next two days will be series of waves
of low pressure and a couple of surface fronts. Today`s showers
and storms, which were already ongoing when the 4 am forecast
package was sent out, will continue to increase in coverage
through out the day, as a wave of low pressure moves eastward
along a sluggish surface frontal boundary. The rain should taper
off a bit overnight, but conditions should still support scattered
shower and storm activity during the night into early Tuesday
morning. Another round of widespread showers and storms are
expected for Tuesday, as cold front moves in from the west.
Showers and storms should be most widespread Tuesday afternoon and
evening as the front begins moving across Kentucky. With strong
instability, ample low level moisture, and decent wind shear,
conditions late in the day Tuesday will support severe weather.
Large hail and damaging wind gusts will both be possible Tuesday,
with locally heavy rainfall, frequent cloud to ground lighting,
and isolated tornadoes being secondary threats.

The models have been a bit all over the place regarding areal
coverage and timing of shower and thunderstorm activity on Tuesday.
The higher resolution models such as the CAMS, HREF, and NAMNEST are
all producing isolated to scattered showers and storms at best on
Tuesday, with most activity only initiating during the mid to late
afternoon. The WPC forecasts have been consistently showing
widespread precipitation affecting the Ohio Valley, Great Lakes, and
upper Midwest regions the past couple of days. Considering how moist
and unstable the atmosphere is going to be today and tomorrow, it
shouldn`t take much to fire showers and storms across our area. That
being said, in spite of the issues the models are having, went with
high precipitation chances across eastern Kentucky today and
Tuesday, especially during the afternoon and evening hours each day.
Scattered showers and storms will likely continue overnight tonight,
as the low level jet remains active. Dewpoints will also likely be
surging into the mid and upper 60s on Tuesday across most of the
area, lending further support to widespread shower and storm
activity and severe weather potential.

With a steady flow of warm moist air surging in the area,
temperatures should remain well above normal to begin the week. We
will see highs today rising into the mid to upper 70s across most of
the area, and into the upper 70s and lower 80s on Tuesday, as
strengthening southerly flow brings even more warm air into the
area. The primary weather concerns today and tomorrow will be the
potential for severe weather on Tuesday and locally heavy rainfall
both days. Confidence is increasing that we will see some sort of
severe weather Tuesday afternoon or evening.

.LONG TERM...(Wednesday through Monday)
Issued at 356 PM EDT MON MAY 6 2024

A warm front will lift northward on Wednesday ahead a surface cold
front and low pressure across the Plains. This will put a good
portion of the Ohio Valley into the warm sector, with decent
agreement on this among the ensemble and deterministic data. The
caveat to Wednesday is how convection evolves Tuesday into Tuesday
night. This thunderstorm activity Wednesday will come in two
waves. The first will be any activity that is able to develop in
the warm sector. These would have to potential to be more
supercell like with all hazards possible. However, it would seem
the better parameter space for this would be central and western
Kentucky, as MLCAPE rises to 2000-3000 J/kg amid 40-50 knots of
effective shear. This would be ample for organizing convection and
all hazards would be possible. The further east you go leads to
less certainty given the potential for morning convection and left
over cloud cover here in eastern Kentucky. However, some medium
range CAM guidance such as experimental C-SHiELD do show some warm
sector supercell potential even here in the east. This will have
to be watched close in forecast updates. Now the second threat
will be a line of convection (QLCS type) that develops ahead of
the front and propagates east Wednesday evening into Wednesday
night. This would pose more of a wind threat, but a quick spin up
tornado can`t be ruled out. This as effective STP values climb to
around 2-3 and effective shear increasing to 40-50 knots through
the evening.

A cold front will push across the area Thursday and will keep
60-90 percent chance of PoPs going mainly in the morning. We will
see storm chances decrease through the day. By Friday, the
ensembles and deterministic show a positively tilted trough axis
pushes into and through the Ohio Valley. This will keep chances of
showers going Friday in the 20-40 percent range. This will also
usher in a cooler airmass, with afternoon highs topping out in the
low to mid 60s. This is around 10 degrees below normal for this
time of year. The somewhat active pattern does tend to roll on
into the weekend, as several shortwaves dive into the Ohio Valley.
The rain chances will generally be in the 20-40 percent range
during this period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 218 PM EDT MON MAY 6 2024

Bit of a messy period starting. Scattered showers and
thunderstorms have been impacting the TAF sites throughout the day
so far. The period is starting off in a bit of a break between
waves, however the western most TAF sites should begin to ramp
back up with showers/storms within the next couple of hours. Most
TAF sites should expect showers and thunderstorms by 22Z. These
will taper off to more scattered and isolated activity by this
evening and overnight, before ramping back up during the daytime
hours on Tuesday. A round of strong to potentially severe storms
will begin to push into eastern KY by the end of the period, and
will continue on into the late afternoon and evening. Overall, TAF
sites should remain VFR outside of any heavier showers or storms
that move through, which could temporarily drop CIGS and VIS. CIGS
will then begin to lower overnight, with several sites expected
to drop to MVFR at times. These lower CIGS may continue into the
day Tuesday. Right now SYM may have the most impacts, as CIGs here
may drop below IFR criteria overnight, recovering to MVFR during
the day tomorrow. Winds will generally be out of the SW throughout
the period and under 10kts, though any showers or storms could
lead to some higher gusts as they move through. After the period
ends, and the next round of storms moves in late Tuesday, can`t
rule out some periods of strong wind gusts, along with the
potential for large hail and possibly even an isolated tornado.

An active TAF period in store, as showers and storms will be
moving across the area today and tonight. The rain will be most
widespread from late this morning through early this evening,
before tapering off to scattered showers and storms overnight.
Conditions will vary from VFR outside of showers and storms, to
MVFR or IFR when an intense shower or storm moves over an airport.
Any storm could produce gusty winds, frequent lightning, and
locally heavy rainfall today. Winds will start out light and
variable, but will increase to 5 to 10kts out of the south or
southwest by 15 or 16Z this morning. Inserted a tempo group in
each TAF to account for any strong storms this afternoon.

&&

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

$$

UPDATE...JMW
SHORT TERM...AR
LONG TERM...DJ
AVIATION...JMW