648
FXUS63 KJKL 291125
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
725 AM EDT Mon Apr 29 2024

.KEY MESSAGES...

- Dry and warm again today with clouds gradually increasing by
  this evening.

- Showers and thunderstorms arrive from west to east tonight and
  linger into Tuesday.

- Dry and trending warmer midweek, followed by showers and storms
  Friday into the weekend.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 342 AM EDT MON APR 29 2024

Very mild once again this afternoon thanks to lingering high
pressure and mainly clear skies, at least in the first half of the
day. High clouds will filter in from west to east this afternoon,
followed by overcast skies after sunset.

Primary item of interest in the short term forecast is the cold
front approaching tonight, bringing a weakening line of showers and
storms. Upper-level jet support will be fleeting tonight, as the 60-
knot 500mb jet lifts northeast over the Great Lakes and weakens.
What remains is the entrance region of a 40-knot jet at 500mb. HREF
and other CAMs advertise MUCAPE near 500-750 j/kg with mid-level
lapse rates near 6.5C/km; marginal for a thunder risk. CAMs
generally advertise a weakening trend in this line of showers and
storms, perhaps with very little rain reaching the far eastern KY
border toward sunrise Tuesday. POPs were generally slowed with this
forecast package and reduced some to account for the anticipated
weakening.

WPC continues to paint our area in an Excessive Rain Outlook.
Overall rainfall amounts are unimpressive through Tuesday (0.50" to
1" in the greater London and Somerset areas; up to 0.50" elsewhere).
This ERO is therefore primarily driven by unseasonably high PWATs of
1.8" (via 00z HREF) which is well above the 1.55" daily maximum per
Nashville sounding climatology. Given the weakening trend discussed
in the preceding paragraph, we are not overly concerned about
excessive rain.

Lastly, in the wake of this line of showers and storms, there is an
opportunity for a few isolated storms Tuesday afternoon. This
appears driven by weak, lingering shortwaves in the low-and-mid
levels, with perhaps a surface influence via washed-out remains of
the cold front (noted in CAMS surface parameters). Confidence is low
in thunderstorms occurring, but signals are present and thus POPs
remain in the forecast. Notably cooler, with highs in the low-to-mid
70s in the wake of the cold front, but right near normal for late
April.

.LONG TERM...(Tuesday night through Sunday)
Issued at 355 AM EDT MON APR 29 2024

The 29/00z model suite analysis beginning Tuesday evening shows an
upper level shortwave trough across the Mid-Ohio Valley down
through the Southern Appalachians. A more substantial upper low/
trough is found over much the Canadian prairie provinces as well
as over northern portions of the CONUS from Washington to the
Dakotas. At the surface, the decaying remnants of a cold frontal
boundary will extend southwestward into Kentucky from a weak low
over the Mid-Atlantic states while weak high pressure is centered
over the Tennessee Valley. Further west, weak low pressure is
found over the northern Plains with an associated cold front
extending southward into Texas.

The first decaying cold front, will decay near/over the Commonwealth
on Tuesday night, with any associated shower activity tapering off.
Heights will begin to rise as the upper level shortwave trough
exits to the east. Thus, skies should clear for the most part,
setting the stage for efficient radiative cooling; which,
combined with light winds and low-level moisture from any rainfall
earlier in the day, will set the stage for fairly extensive
radiation fog formation through the overnight. By Wednesday, the
upper level low over the northwest CONUS will begin to amplify
while a counterbalancing ridge begins to rise across the Ohio
Valley and Southern/Central Appalachians, reaching peak intensity
late Thursday. This will funnel very warm air mass northward
across the eastern Kentucky Coalfields, especially on Thursday
when 850mb temperatures may exceed 17C (40-60% chance south of
I-64, less than 40% north). Given deep mixing, 850 mb temperatures
of this magnitude would easily support temperatures warming to
near record levels in the mid and upper 80s. The amplified pattern
begins to break down on Thursday night and Friday, with the ridge
being shunted southeast while the western upper low tracks toward
the Hudson Bay. As this occurs,a surface low reflection will
develop and track from the Plains into northern Ontario and push
a cold front, and renewed rain chances, into eastern Kentucky on
Friday into Saturday. Little in the way of forcing will leave the
surface front hanging up near/south of our forecast area this
weekend. Model agreement then diverges significantly with respect
to the overall pattern, though there are suggestions that a
disturbance could ride along the boundary and bring rain chances
on Sunday as well.

In sensible terms, the first day of May will likely start off
foggy for many of the valley locales before yielding to ample
sunshine area-wide. Wednesday will turn quite warm with high
temperatures forecast to reach the upper 70s to lower 80s. Even
hotter temperatures, in the middle to upper 80s, are on tap for
Thursday under bright May sunshine. A few isolated 90 degree
readings cannot be ruled out, most likely in the deep valleys of
the Big Sandy river basin. Shower and thunder chances return on
Friday as the next cold front arrives. However, temperatures are
still forecast to jump into the 80s before the deeper moisture
moves in. Periodic shower and thunderstorm chances are also in
the forecast heading through the weekend as that front stalls and
potentially becomes the focus for additional rainfall, at times,
over the weekend, though forecaster confidence in the details is
low. Daily maximum temperatures are forecast to drop back into the
mid 70s to lower 80s for the both weekend days. Nighttime lows
should mainly range between 52 and 67 through the period, coolest
Tuesday night and warmest on Thursday night.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
ISSUED AT 724 AM EDT MON APR 29 2024

Majority of the TAFs were in excellent shape this morning amid
quiet weather conditions. Detail was added late in this TAF
period to account for -SHRA and falling ceilings. A weakening line
of showers (and perhaps thunderstorms) is expected to move from
west to east late tonight. Due to the weakening trend, and
continued slower/later arrival in latest high resolution
guidance, confidence is low for the arrival time of -SHRA. MVFR
ceilings are favored just outside of this TAF period according to
the in- house blend.


&&

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

$$

SHORT TERM...BROWN
LONG TERM...GEERTSON
AVIATION...BROWN