-- Discussion containing changed information from previous version are highlighted. --
600
FXUS63 KJKL 230819
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
419 AM EDT Mon Sep 23 2024

.KEY MESSAGES...

-- Changed Discussion --
- A more unstable and wetter pattern will keep the potential for
  showers and thunderstorms going through much of this week.

- High temperatures will climb into the After high temperatures
  well into the 80s to near 90 earlier today, readings will trend
  downward through the week.
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&&

.SHORT TERM...
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(Today through Tuesday)
Issued at 419 AM EDT MON SEP 23 2024

Aloft, flattened ridge continues to be broken down by shortwave
energy associated with a trough moving out of the central Plains
and into the Ohio Valley. This trough manages to make it into
eastern portions of the Commonwealth by the end of the short term,
just as another, deeper system drops southward into the Missouri
Valley. At the surface, a nearly stationary frontal zone is
positioned along the Ohio River just to our northwest. This
feature, combined with passing disturbances aloft, will provide a
focus for sporadic episodes of showers and thunderstorms across
eastern Kentucky through the period.

Sensible weather features a generally unsettled short term, with
periods of showers and thunderstorms impacting different portions
of eastern Kentucky, as well as the region, at times through the
short term. H850 temps between 16-17C combined with the increased
cloud cover and higher potential in PoPs will help keep afternoon
highs in the upper 70s to mid 80s through the period, or about
5-10 degrees lower than the recent upper 80s to lower 90s we have
been experiencing.

The Storm Prediction Center has our area in a Marginal risk for
severe weather today and again on Tuesday. In addition, the
Weather Prediction center has our area in a Marginal risk for
excessive rainfall. Overall, the risk for strong to severe storms
will be conditional, as is often the case it seems. Today, we will
see marginal instability, on the order of 500-1000 J/kg of MLCAPE
and bulk shear is lacking, generally less than 25kt, though it
does increase to around 30 kts tonight. Mid-level lapse rates are
modest, climbing to around 6 C/km. However, there is a relative
lack of triggers through much of the day as the better, more
organized shortwave energy holds off until later tonight and
Tuesday. Thus we will be dependent on the surface front to our
northwest and differential heating to help initiate convection
today. This suggest convection will be more isolated to scattered
today, and less organized. But there are enough ingredients in
place that a strong storm or two could not be ruled out. Tuesday
appears more favorable for strong to severe storms with MLCAPEs on
the order of 1000-2000 J/kg, and bulk shear of 40-50 kts.
However, mid-level lapse rates are weaker. In addition, it is
likely that there will be more cloud cover across the region on
Tuesday. Consequently, severe weather potential will be increase
with more sunshine...or heating. Shortwave energy appears more
organized on Tuesday. Thus convection, as well as the potential
for strong to severe storms appears more likely on Tuesday.

Storm motions are decent through the period, 10-15 kts today,
increasing to around 30 kts or greater by Tuesday. Freezing levels
are generally less than 13 kft and PWATS max out at around the
75th percentile, climatologically. Thus conditions are not ideal
for widespread flooding issues. Everything considered, feel that
any hydro issues will be localized, and more dependent on how
organized convection becomes and the potential of training and/or
the back building of storms over specific locations.

.LONG TERM...(Tuesday through Sunday)
Issued at 335 PM EDT SUN SEP 22 2024

The latest run of the GFS has an active flow pattern aloft across
the CONUS. A trough of low pressure is currently forecast to be
coming onshore in central California on Tuesday, with another
well developed trough positioned over the northern Plains.
Another persistent trough is still in the picture off the eastern
seaboard to begin the period on Tuesday, but looks like it will be
a bit further offshore. Another feature of great interest in the
extended will be the development of a tropical cyclone in the
southern Gulf of Mexico toward the middle of the week. Based on
the latest model runs, it is looking more and more likely that a
tropical cyclone will form somewhere over the Gulf of Mexico, and
perhaps rapidly intensify over those extremely warm waters as it
moves northward toward the central or eastern Gulf Coast. There is
quite a bit of uncertainty regarding how this system will evolve
and progress once it moves inland, should it indeed form, and how
it might affect the weather of eastern Kentucky, so we`ll be
watching this particular feature quite closely over the coming
days.

Our first weather maker, however, will be the northern Plains
trough and frontal systems that will be extending from it. The
latest models suggest that a weak shortwave may also form along
the leading edge of the approaching trough on Tuesday. This, along
with the passage of a surface cold front, will act as sources of
lift to support shower and storm formation across our area.
Showers and storms will move in from the north and west, as the
cold front moves through. With a potential tropical cyclone moving
in from the south, the front could slow up greatly, or even stall,
over our area. If this scenario occurs, it would mean an extended
period of light to perhaps moderate rainfall across our area
Tuesday through Thursday. As much one to three inches could fall
over the area during that three day period.

With extensive cloud cover and persistent precipitation expected
across our area for at least a few days, temperatures should be
near normal during the extended, and perhaps even a few degrees
below normal at times. Daily highs will range from the low to mid
70s on the coolest days, to the mid to upper 70s or even lower 80s
on the warmest day. As far as hazards go, we`ll be watching
closely for the potential for locally heavy rainfall during the
Tuesday through Thursday time frame, when the most widespread and
persistent rain is expected to occur. There is also a marginal
risk, or 10% probability, that severe storms will occur on Monday,
as the cold front makes its initial push through the region.
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&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
ISSUED AT 157 AM EDT MON SEP 23 2024

Surface cold frontal zone is draped along the Ohio River just to
our northwest. Subtle disturbances continue to track through the
Ohio Valley, producing additional shower and thunderstorm
activity, some of which is redeveloping just upstream of our
forecast area at TAF issuance time. The strongest of this activity
will impact mainly KSYM, KSME, and possibly KLOZ. Otherwise, some
light showers are also moving through the area. Thus far activity
could be described as sporadic and diverse in nature, making it
more of a forecast challenge with respect to predominant weather
groups at any given location. Overall this leads to a lower than
normal confidence level with respect to flight categories at any
given period of time. In general, feel VFR conditions are a
reasonable bet, but there will be drops in flight conditions,
particularly VSBYS where showers and thunderstorms do pass. Model
guidance, and especially higher resolution short term convective
allowing models show an overall downward trend in activity through
the remainder of the overnight. Thereafter, expect convection may
redevelop and overspread eastern Kentucky from southwest to
northeast by around mid-afternoon. Once this activity dies down,
fog will likely redevelop late in the period. Winds will be light
and variable through the period, except in the vicinity of any
thunderstorms where winds could become gusty.

&&

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

$$

SHORT TERM...RAY
LONG TERM...AR
AVIATION...CMC/GREIF/RAY