Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 240821
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
421 AM EDT Sun Mar 24 2024

.KEY MESSAGES...

- Freezing temperatures are forecast for some of the deeper
  valleys tonight.

- A critically dry air mass and an increase in southeast downslope
  winds will result in increased fire danger Monday.

- Warmer conditions return for Monday before another round of
  widespread rainfall late Monday night and Tuesday. A few
  thunderstorms will be possible across the area late Monday night
  and Tuesday morning, mainly near and west of Interstate 75.

- Temperatures cool within a few degrees of normal from Tuesday to
  the end of next week, with the threat for sub-freezing
  temperatures returning for many valley locations on Wednesday
  and Thursday nights.

&&

.SHORT TERM...(Today through Monday)
Issued at 335 AM EDT SUN MAR 24 2024

The short term period will be characterized by high pressure
remaining to our northeast while a major storm system spins up
across the Central US. The result will be rain-free conditions and a
pronounced warm-up, but also increasing fire weather concerns
tonight and especially Monday as southeasterly downslope winds
increase with an increasing pressure gradient.

A dry air mass is evident over the region early this morning,
especially ridgetops, with light northeasterly flow from high
pressure to our north and northeast. Warm advection today with sunny
skies will allow for highs to reach the mid-50s north to mid-60s
south, with only a little bit of shading from increasing mid- and
high-level clouds during the afternoon hours.

Surface high pressure wedges down the eastern side of the
Appalachians at the same time as a low pressure deepens over the
Central Plains tonight. This results in an increased southeasterly
winds tonight as the pressure gradient becomes maximized over the
immediate western slopes of the southern Appalachians. For
temperatures, this will mean mild and very dry conditions with poor
humidity recovery over higher terrain and ridgetops, with better but
still relatively modest humidity recovery in the broader valleys.
This will result in elevated fire weather conditions that will only
worsen heading into the day Monday. Lows tonight/Monday morning will
only fall into the lower to mid 40s on ridgetops with near-freezing
temperatures in the deeper sheltered valleys. It should be noted
that if cloud cover is a bit thicker than forecast the ridge/valley
temperature difference may not be as high as currently forecast.

Critically dry conditions Monday along with the increase in
southeast winds will result in highly elevated to locally critical
fire weather conditions, with widespread minimum RH values well into
the teens expected. Southeasterly sustained winds will remain below
levels needed for fire weather warnings but gusts in the 20s will
result in increased fire danger. Given the extremely dry lower and
mid-levels forecasted by models as well as the southeasterly
downslope winds, the deterministic NBM forecast was raised by 2 to 4
degrees to result in widespread 70s for highs.

.LONG TERM...(Monday night through Saturday)
Issued at 421 AM EDT SUN MAR 24 2024

The 24/00z model suite remains in good agreement initially on Monday
evening. A deep 500H trough, with an embedded ~535 dam low over
Kansas, will be tilting negatively across the Plains. An associated
~990 mb surface low will passing near/over Kansas City, Missouri.
Meanwhile, high pressure ridging of recent days will be moving
off the Atlantic Seaboard.

As that 500H trough continues to translate eastward, it will take
on a more negative tilt and deamplify into Wednesday. During this
time, the system`s surface low gradually weakens as it tracks
into the Upper Great Lakes by Tuesday evening and on toward James
Bay Wednesday. The system`s warm conveyor belt jet quickly pulls a
warm front northward across the Ohio Valley late Monday night and
Tuesday morning. The system`s trailing cold front will be less
decisive in its eastward progress as the upper level forcing
diminishes. A surface theta-e analysis suggests that the front
slowly bleeds east across the forecast area on Tuesday Night and
Wednesday. By Thursday, additional energy passing around the base
of the 500H trough causes re-amplification over the Southeast US
and induces renewed cyclogenesis as the cold front approaches the
Atlantic Seaboard. As this occurs, we will see cooler and drier air
gradually infiltrate Central Appalachia later Wednesday and on
into Thursday. Subsequent high pressure ridging, both aloft and
at the surface, will setup across our region on Thursday night
and Friday. This ridging then breaks down heading into next
weekend as another cold front tries to drop in from the north,
though with little upper level support. Model agreement
deteriorates with respect to how that boundary plays out as we
prepare to welcome a new month.

Sensible weather will feature a dry and rather gusty Monday evening
as the surface pressure gradient tightens over the eastern
Kentucky. Locally, near critical fire weather conditions cannot be
ruled out, particularly over the southeastern high terrain
initially. However, gradual moistening ahead of the warm front
should eventually lead to some relief from the dry conditions
later in the night. Anticipate a zone or line of shower activity
to lift across the forecast area either late Monday night or early
Tuesday morning with the passage of the warm front. A stray
rumble of thunder cannot be ruled out with this activity,
primarily near and west of I-75. Temperatures will be mild,
ranging from the upper 40s to lower 50s for most Monday night
before warming back into the lower and middle 60s on Tuesday.
Once the initial round of showers passes on Tuesday, expect a lot
of clouds along with plenty of rain-free time. Showers may become
a little more numerous again late in the day ahead of the cold
front, but don`t expect anything strong due to the lack of
instability. Those showers only slowly drop southeast and depart
on Wednesday, perhaps evening lingering into Thursday immediately
adjacent to the Kentucky/Virginia border. System total QPF has
diminished to between 0.35 and 0.55 inches. Wednesday will still
be mild with morning lows in the mid 40s to lower 50s and
afternoon highs in the upper 50s to mid 60s. Looking ahead to
Thursday, temperatures will likely stay in the 50s as the cooler
and drier mass becomes more firmly in place over eastern Kentucky.
Nighttime temperatures will fall to near or below freezing at
many valley locations on Thursday night and again on Friday night,
in spite of temperatures moderating back into the 60s for highs
on Friday afternoon. Low rain chances return for the weekend with
the approach of the next cold front, though the specific details
remain uncertain at this point.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
ISSUED AT 133 AM EDT SUN MAR 24 2024

VFR conditions will prevail for the TAF period under clear skies
tonight and Sunday morning giving way to increasing mid- and
high-level cloud cover during the afternoon through the remainder
of the TAF period. Light northeast winds 10 kts or less will
become more easterly with time and then southeasterly and light by
the end of the TAF period, with deeper valley locations remaining
light and variable in the overnight and morning periods.

&&

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

$$

SHORT TERM...CMC
LONG TERM...GEERTSON
AVIATION...CMC


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