Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 180850
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
450 AM EDT Mon Mar 18 2024

.KEY MESSAGES...

- A deep trough passing aloft brings a threat of light snow
  showers and flurries this afternoon.

- A hard freeze later tonight could kill any cold sensitive
  vegetation that has emerged prematurely due to early season
  warmth.

- Gusty southwest winds transport warmer air into the region on
  Tuesday, but dewpoints are slower to rise leading to low
  afternoon relative humidity and Fire Weather concerns.

- Temperatures rebound back to near normal for Wed and into next
  weekend, with lower confidence in the next potential chance of
  precipitation moving in towards the end of the work week.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 450 AM EDT MON MAR 18 2024

08Z sfc analysis shows high pressure attempting to build into
eastern Kentucky from the west. However, a passing trough aloft
will help to maintain cyclonic sfc flow over the area into the
evening. This flow is responsible for the chilly temperatures this
morning on northwest winds of 10 mph or less. Accordingly,
readings are running in the low to mid 30s most places with a few
sheltered spots able to cool into the upper 20s. Meanwhile,
dewpoints are lower than temperatures, generally in the upper
teens to lower 20s under a smattering of mainly high clouds.

The models, and their individual ensemble suites, continue to be
in pretty good agreement aloft through the short term portion of
the forecast. They all depict a deep trough tilting through the
southern Ohio Valley and across the Tennessee Valley today. This
brings strong height falls, steep lapse rates, and a cluster of
mid level energy through our moisture starved area this
afternoon. This trough bottoms out to our south this evening and
slips quickly east of the Appalachians leaving lower heights and
northwest flow at 5h behind. The now very small model spread
supports using the NBM as the starting point for the forecast
grids with most adjustments related to terrain distinctions in
temperatures tonight as well as extra mix down drying on Tuesday
afternoon.

Sensible weather will feature a cold day after our warmth of late
with a northwest breeze adding to the chill. Dry conditions in
the boundary layer should keep any light pcpn in the form of
flurries and sprinkles, though an influx of moisture from the
Great Lakes may be enough for a stray shower of light rain or
snow (10 percent threat or less) - but more probable northeast of
the JKL CWA. The clouds and light pcpn associated with the
passing trough aloft will move off to the east tonight. These
conditions, when combined with diminishing winds, will allow for
better for better radiational cooling and a ridge to valley
temperature difference to set up overnight and into Tuesday
morning - enhancing the widespread hard freeze in the valleys
especially. The recent warmth has encouraged many buds and
blossoms to develop on the vegetation throughout the area and
these are seriously threatened by tonight`s cold. For this reason
(as the growing season has not been declared started, yet) an SPS
has been issued giving heads up to those with agricultural and
fruit tree interests. For Wednesday, the dry conditions combined
with rebounding temperatures on breezy southwest winds will lead
to humidity values well below 25 percent, for most. Combined with
the winds pushing 15 mph sustained, at times, from mid morning
into the afternoon there will be heightened fire weather concerns
and a Red Flag Warning may be needed for at least portions of the
forecast area for the latter part of the day. This concern will be
addressed in the narrative portion of the forthcoming Fire
Weather Forecast product.

The main adjustments to the NBM starting point were to include
more terrain distinction for temperatures tonight and also favor
the 10 percent or lower version of the NBM for dewpoints on
Tuesday afternoon.

.LONG TERM...(Tuesday through Sunday)
Issued at 332 PM EDT SUN MAR 17 2024

The primary forecast concerns in the extended will be the potential
for low dewpoints and very dry conditions across the area on Tuesday
and generally above normal temperatures. With winds still expected
to be blustery and perhaps a bit gusty to begin the period, there
could be some fire weather concerns for eastern Kentucky. This
threat has been highlighted in the HWO. A ridge of high pressure
will be the dominant weather system to start, but a weak area of
low pressure passing by to our south, will bring rain chances back
into the picture late in the week and into the upcoming weekend.

The overall large scale upper level pattern to begin the period will
feature a trough of low pressure moving slowly into and across the
Desert Southwest and across the southern CONUS over time. This will
be the system that brings rain to our area toward the end of the
period. High pressure will dominate the weather of the southeastern
CONUS initially, but another expansive trough of low pressure is
forecast to dive southward out of Canada Wednesday and Wednesday
night. Since it appears this system will be moisture starved, we
should see nothing more than scattered clouds across the area as
this system moves through aloft to our north and northeast. The
southern stream trough mentioned earlier, will be our next weather
maker Thursday night through Sunday. Another weak northern stream
system might also be moving through during this time, and could
influence our weather as well, but the southern stream low still
looks like the main show.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
ISSUED AT 155 AM EDT MON MAR 18 2024

VFR conditions will prevail through the period with just a
smattering of high clouds into daybreak. A passing deep upper
level disturbance will move through the region during the day.
This brings scattered to broken clouds ranging from 4-6k feet
agl, with perhaps a fleeting sprinkle or flurry. Winds will
continue to be the main aviation concern at the terminals, though.
They will be light into dawn then pick up from the northwest
increasing to around 10 kts, with gusts of 15 to 20 kts by mid to
late morning, as deeper mixing commences across the area.

&&

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

$$

SHORT TERM...GREIF
LONG TERM...AR
AVIATION...GEOGERIAN/GREIF


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