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953
FXUS63 KJKL 120333 AAB
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1133 PM EDT Sat May 11 2024

.KEY MESSAGES...

- Some showers and perhaps a storm or two are possible, at times,
  this afternoon.

- Precipitation free weather is anticipated from tonight into
  Monday morning, before more unsettled weather returns.

- Expect rather cool temperatures through the weekend, with
  milder weather then returning.

&&

.UPDATE...
-- Changed Discussion --
Issued at 1133 PM EDT SAT MAY 11 2024

Updated the forecast package to emphasize tonight`s ridge valley
split just a bit better. Also beefed up fog across the area for the
remainder of the night. CAMs and ensemble data suggest surface dew
points should drop some through the overnight as drier air advects
into eastern Kentucky. Seeing a hint of that in the surface obs as
well. However, model guidance tends to keep Tds up through the
night. Seeing some fog formation in some of the more sheltered
valleys to our east. Forecast challenge is how much drier air will
be able to advect into the area versus surface dew points
leveling off or possible even rebounding a bit as the boundary
layer continues to decouple and grow in depth. As stated before,
surface dew points should rebound slightly or the drop should slow
and possibly level off. As temperatures continue to drop closer
to dew points, and we are beginning to see a more substantial drop
off now, believe conditions will become more favorable for some
fog development, particularly around or near sources of water.
Have made corresponding adjustments to the forecast package for
this latest line of thinking. Overnight lows looked on target for
our valley locations, however, raised the ridge top temps just a
couple degrees, which would be more in line with current
observations at our ridgetop sites. Updated zones and grids have
already been issued.

UPDATE Issued at 830 PM EDT SAT MAY 11 2024

Based on the current regional radar, the threat of any shower
activity over eastern Kentucky has waning quickly over the past
hour. Removed PoPs for the evening update and updated hourly T/Td
to capture the most recent hourly trends. With high pressure
moving into the area overnight, skies will continue to clear.
Difficult to say how much fog there will be overnight. With a
post frontal gradient wind am inclined to forego fog. But surface
dew points should rebound slightly with decoupling of the
boundary layer and expect winds will slacken enough for some
patchy valley fog to develop, particularly around or near sources
of water. Went ahead and freshened up the zones as well. No other
changes to the forecast package at this time. Updated zones and
grids will be issued shortly.
-- End Changed Discussion --

&&

.SHORT TERM...(This evening through Sunday night)
Issued at 322 PM EDT SAT MAY 11 2024

Last in a train of short-wave troughs has shifted just east of our
area this hour. This shift and more ridging building in should bring
a period of more tranquil weather for the short term. Skies should
become mostly clear tonight, allowing for another night of aurora
watching should those colors swing by here again. Similar to this
morning, temperatures by Sunday morning should fall into the 40s for
most locations in eastern KY. High pressure crossing overhead again
will mean some potential for valley fog formation.

Under more sunshine Sunday, highs should reach well into the 70s,
close to normal for mid May. Weak southerly flow Sunday night, as
that surface high shifts southeast of the region, will mean
temperatures a little warmer by Monday morning, with lows in the
mid 40s to low 50s.

.LONG TERM...(Monday through Saturday)
Issued at 500 PM EDT SAT MAY 11 2024

The 11/12z model suite is in good agreement from Monday morning
through Wednesday but increasingly divergent thereafter. At the
start of the forecast period on Monday, a forecaster model
analysis shows upper level shortwave ridging in place over the
Ohio Valley. A corresponding surface high pressure is found along
the Mid-Atlantic coast. Upstream, a weak upper level trough/low
and associated surface low are found over the Central Plains.
Further upstream, another shortwave trough is moving into the
northern Rockies while another subtle low is drifting off the
California Coast.

The high pressure ridging initially in overhead and at the
surface will depart to the east on Monday as the system over the
Plains approaches. The threat for rain returns to eastern Kentucky
late Monday and persists throughout Tuesday before slowly tapering
off from the northwest on Wednesday once the system`s trailing
cold front passes through our area. Weak instability and shear
will keep any threat for severe storms in check. While PWATs
aren`t spectacular, there does appear to be a period elevated 850
mb moisture convergence under notable upper level divergence on
Tuesday afternoon and evening just ahead of the surface low. This
may lead to a period of steady moderate rain for portions of the
area. WPC has issued a Marginal risk ERO for this time period,
which seems reasonable given the setup. Further out in the long
term, the specific details become more hazy due to the greater
model spread. However, high pressure ridging does appear to make
at least a brief return late Wednesday or early Thursday.
Meanwhile, the northern Rockies trough and Pacific low will
translate eastward and phase into a trough that will negatively
pivot across the eastern CONUS late in the week, potentially
sending another surface low across the Ohio Valley.

The sensible weather is forecast to be rather unsettled during
most of the long term. The dry weather on Monday will be fleeting
as clouds increase and showers advance from the west during the
afternoon and evening. Expect high temperatures to range from the
mid 70s to lower 80s, coolest west of I-75 where clouds
thicken/precipitation arrive first and warmest in the valleys of
the Big Sandy basin where sunshine prevails the longest. From
Monday night through Wednesday, showers, interspersed with a few
thunderstorms, will be prevalent. The clouds and precipitation
will lead to suppressed diurnal temperature ranges with lows
mainly in the 55 to 60 range and highs generally in the 70s. A
general 1 to 2 inches of rain expected to fall across the area
during this timeframe. Clearer and drier weather then makes a
brief return Wednesday into Thursday ahead of more showers and
possible thunderstorms late Thursday into Saturday. High
temperatures are forecast to warm back into the mid 70s to lower
80s for the remainder of the forecast period. Nighttime lows
remain mild, primarily in the 50 to 60 range, though a few
readings in the upper 40s are possible in the coldest valleys
late Wednesday night and early Thursday morning.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 112 PM EDT SAT MAY 11 2024

Most active period this forecast cycle is in the first few hours,
with a band of clouds and associated showers progged to move
across the terminals this afternoon. Cannot rule out an isolated
tick of lightning, but not high enough confidence in any one site
to include in this set of TAFs. Winds will pick up from the west
and west northwest as well, with gusts of 15-20 kts. Winds will
die down quickly this evening with skies becoming partly cloudy to
clear.

&&

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

$$

UPDATE...RAY
SHORT TERM...SHARP
LONG TERM...GEERTSON
AVIATION...SHARP