623
FXUS63 KJKL 221935
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
335 PM EDT Sun Sep 22 2024

.KEY MESSAGES...

- A potential for showers and thunderstorms will persist through
  much of this week.

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

&&

.SHORT TERM...(This evening through Monday night)
Issued at 302 PM EDT SUN SEP 22 2024

The frontal boundary that had been draped across far northern
Kentucky has begun to move north into Ohio and West Virginia as warm
advection increases across central and eastern Kentucky. Upstream
over the mid-Mississippi River Valley, a disturbance continues to
move east toward eastern Kentucky, and will be the primary trigger
for shower and thunderstorm development later this afternoon into
the early evening. The greatest instability will be over the
southwestern quadrant of the forecast area, but there will be
sufficient instability for thunderstorms anywhere across the
forecast area into this evening.

Additional rounds of showers and thunderstorms are possible into the
overnight tonight, with the greatest instability over the southern
half of the forecast area, as an active jet stream continues to
usher disturbances across Kentucky. With at least broken cloud cover
and continued warm advection, expect little in the way of any ridge-
valley temperature differences. Fog will be dependent on the amount
of cloud cover.

A stronger southwesterly jet stream develops over Kentucky Monday,
and this combined with stronger moisture advection into the area
will result in MLCAPE values approaching 1500-2000 J/kg by early
to mid-afternoon. The increasing shear and sufficient instability
will mean a Marginal Risk for severe thunderstorms, with gusty
winds and large hail the primary severe threats. A mitigating
factor may be that the better shear does not arrive until after
sunset, when instability becomes more limited, especially if
earlier convective overturning has resulted in stabilization of
the atmosphere. With the strong upper trough still approaching
from the west, showers and thunderstorms are likely to continue
through the overnight Monday night. Despite the recent dry
conditions, isolated/localized instances of high water are
possible where storms train across particular area.

.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.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
ISSUED AT 124 PM EDT SUN SEP 22 2024

Mainly VFR conditions are expected to last into tonight. However,
isolated thunderstorms are forecast to this afternoon and last
into the evening before dissipating. Additional scattered showers
and thunderstorms may occur overnight, but this is lower
confidence. Any thunderstorm or heavy shower has the potential to
bring sub-VFR conditions. Valley fog and low status are also
forecast once again tonight, but its extent is questionable. If
significant precip occurs first, it would favor fog. However, the
presence of clouds would also inhibit fog development. Additional
more widespread showers and thunderstorms are expected to develop
at the very end of the TAF period, which will be reflected in
future TAF packages.

&&

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

$$

SHORT TERM...CMC
LONG TERM...AR
AVIATION...CMC