653
FXUS63 KJKL 041849
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
249 PM EDT Tue Jun 4 2024

.KEY MESSAGES...

- The threat of showers and thunderstorms will increase through
  mid-week.

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

&&

.UPDATE...
Issued at 1231 PM EDT TUE JUN 4 2024

With an increase in sfc dewpoints and moisture through the column,
convective temperatures are being reached across portions of the
region. Some showers and a few thunderstorms having developed
over the past half hour to hour. These appear to generally have
formed within the PW gradient per Mesoanalysis with values near
1.2 inches near the WV border and in northeast KY with values of
1.6 inches or higher near Lake Cumberland. Additional activity
over central and western KY to middle TN/Cumberland Plateau of TN
should also move toward the region. During peak heating additional
development may also occur. Adjustments to pops have been made to
bring isolated to scattered levels to the WV border quicker
compared to the previous forecast. Additional minor changes to
hourly temperatures were made based on recent observations.

UPDATE Issued at 1100 AM EDT TUE JUN 4 2024

Hourly grids were updated based on recent radar, satellite, and
observation trends. Overall, this led to no substantial changes
other than to slow down the increase in clouds and the diurnal
increase in pops a couple of hours in line with more recent CAMS
and extrapolation of satellite and radar.

UPDATE Issued at 745 AM EDT TUE JUN 4 2024

Clouds are a little slower to thicken this morning than earlier
forecast, and a slight adjustment has been made. Also, overnight
mesoscale model runs are suggesting that precip may last longer
into tonight. Not a lot of confidence in exactly how it plays out,
but have trended the forecast toward a later decline.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 450 AM EDT TUE JUN 4 2024

Mid/upper level ridging is slowly shifting eastward away from our
area early this morning. This will open us up to the influence of
a deepening and growing mid/upper level low migrating slowly east
southeast over south central Canada, and shortwave impulses
circulating around it. One of these waves will move northeast over
the region today and interact with moist low level flow out of
the south to produce scattered to numerous showers and
thunderstorms. Activity should peak late in the day and decrease
tonight as the initial wave aloft departs and we cool/stabilize. A
second wave circulating around the large scale low will approach
from the west on Wednesday. It will again take advantage of a flow
of moist air into the area from the south southwest and lead to
shower and thunderstorm development, with activity again peaking
late in the day. There is not model agreement on the QPF and
coverage on Wednesday, and a blended solution was used with POPs
of around 70%.

.LONG TERM...(Thursday through Tuesday)
Issued at 248 PM EDT TUE JUN 4 2024

General agreement continues with respect to the mid/upper level
patterns aloft. An elongated low and associated trough will have
spun its way into the Great Lakes region at the start of the
extended. The low...or mean low sets up residence over the Great
Lakes for the remainder of the period, sending additional short wave
impulses around the southern periphery of the mean low, into the
Ohio Valley. At the surface, a relatively strong surface cold front
will move through eastern Kentucky late Thursday or Thursday night.
A stacked low over the Great Lakes, will keep our area under the
influence of northwest flow. Subtle short wave disturbances passing
across the region combined with wrap around moisture and diurnal
heating will keep a general 20-30 PoP going through the period, with
a noticeable diurnal flavor to activity.

Sensible weather features generally dry weather for many, though
isolated to widely scattered showers, commonly referred to as hit or
miss showers and thunderstorms could impact anyone on any given day
and at any given time. However, the most likely window of time for
rain would be in the afternoon and early evening time frames. Other
than Thursday morning at the start of the period, Saturday
afternoon/evening and again Sunday afternoon are the next most
likely day of more widespread rain as PoPs increasing to around 30-
35% as another cold frontal system approaches and passes through the
Ohio Valley. After Thursday`s low to mid 80s for max temps, daily
highs will average around 5 degrees below normal, or mid 70s through
the period. Our coolest day through the extended will be Friday,
with Saturday being slightly warmer by a degree or two. With lower
surface dew points in the low 50s and a gradient wind around 10 mph,
Friday will feel the coolest. Overnight lows will run in the 50s,
though we may be flirting with upper 40s in some of our coolest
valley locations by Saturday morning.

Not seeing any solid signals with respect to hazards through the
period. Instability will be relatively low, with MLCAPES only
climbing to between 750 and 1250 J/kg Thursday afternoon.
Instability looks even weaker for Sunday. At this time effective
shear is not even reaching marginal levels. Thus any organized
convection will likely be limited to features such as frontal
boundaries.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 153 PM EDT TUE JUN 4 2024

An increase in moisture, combined with daytime heating and the
approach of a couple of disturbances from the southwest, has
allowed isolated to scattered showers and thunderstorms to
develop across portions of the region. The activity should linger
into the evening, but with a general decrease in coverage between
00Z and 06Z. Confidence in timing/placement is too low for
anything more than VCTS to be mentioned in TAFs at this point,
though KSJS and KSYM appear to have the best chance for thunder
possibly on station over the next hour or two followed by KLOZ
and KSME. Some periods of MVFR or lower vis and or ceilings are
anticipated where the stronger showers and storms pass and a
brief gust into the 20 to 30KT is also possible. Fog could be a
concern tonight where rain occurs if clearing becomes substantial
enough, but due to lack of confidence is not included at this
time. After an anticipated lull in activity between about 06Z and
12Z, coverage may again increase to end the period.

&&

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

$$

UPDATE...JP
SHORT TERM...HAL
LONG TERM...RAY/CMC
AVIATION...JP