Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 260845
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
445 AM EDT Tue Mar 26 2024

.KEY MESSAGES...

- A few thunderstorms will be possible across the area through
  this morning. Otherwise, widespread showers will move across
  the area this morning through this afternoon.

- Temperatures cool to within a few degrees of normal today
  through Friday, with the threat for sub-freezing temperatures
  returning for many western valley locations Thursday morning and
  all valley areas Friday morning.

- PoPs start to creep back in from the northwest this weekend,
  with temperatures returning to around 10 degrees above normal.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 400 AM EDT TUE MAR 26 2024

A pre-frontal band of showers and thunderstorms continue to slowly
trek eastward this morning largely coinciding with the jet streaks
at the 850- to 700-hPa levels ahead of a strong cyclone over the
Upper Mississippi River Valley. This jet stream will only slowly
move across the area through the early to mid-afternoon, with a dry
slot moving northeast across the area by late afternoon and early
evening ending most of the widespread shower activity and allowing
for partial clearing of skies. The surface cold front itself crosses
the region tonight, with some models showing a frontal band of
showers moving into our northern half of counties as it moves across
the region.

As the front moves slowly east of the area late tonight into
Wednesday, weak high pressure begins to move into the region but
aloft the region will remain within the PVA region downstream of the
large upper trough over the Central US.

Widespread precipitation will mean temperatures today will not rise
much from where they have been during the early morning hours, with
highs generally ranging from the upper 50s to mid 60s. Cooler air
moves into the region tonight from the west with lows generally in
the upper 30s and lower 40s west to upper 40s east where clouds
linger the longest. Wednesday`s highs will be near to about 5
degrees above normal in the lower to mid 60s as southwest flow aloft
continues across the region, strongest toward the Virginia border.

.LONG TERM...(Wednesday night through Monday)
Issued at 445 AM EDT TUE MAR 26 2024

Aloft, deep east CONUS trough will transit the Ohio Valley,
moving quickly eastward out of the region by Thursday evening. A
zonal flow regime sets up east of the Mississippi behind the
departing trough by this weekend. A series of shortwave
disturbances within the zonal flow will pass through the
Commonwealth from time to time through the remainder of the
period. There is poor model agreement during the last 24 hours of
the extended, but in general a western trough and deeper low
appears to lift out of the Baja of California and heads eastward
across the CONUS. This feature may begin to impact the lower Ohio
Valley by the end of the forecast window, or more likely just
beyond. At the surface, and under the response to strengthening
zonal flow aloft, a baroclinic zone will gradually develop and
strengthen across the Midwest and eventually along the Ohio River
Valley, oscillating to the south sometime next weekend and then
back to the north early next week in response to a passing
shortwave features.

Sensible weather features a dry start to the extended. However,
with the baroclinic zone, or by extension surface frontal zone
setting up across the region, the return of the threat of rain
should be expected by next weekend and thereafter. PoPs should
start out low at first, but increase with time through the weekend
and into the new week as the baroclinic zones strengthens and
drops southward towards the area. PWATS increase in general while
H850 mb transport winds advect moisture in from the west-southwest
through the weekend and especially early next week, as a frontal
zone generally sags southward more directly over eastern Kentucky.
Slight chance PoPs (20%) will return from the northwest as early
as late Friday night. Small chance PoPs (20-30%) will then
continue to threaten a larger portion of the forecast area through
the weekend, with even a threat of some thunderstorms at times.
By early next week, PoPs increase to good chance (40-60%), as
deeper moisture and more organized forcing arrive. Temperatures
will gradually modify through the period, as surface high pressure
shifts to the east and return southerly flow ensues. Temperatures
will trend back to around 10 degrees above normal towards the end
of the period.

Main hazards for the extended will be sub freezing temperatures
for many of our western valley locations Thursday morning as a
dry, cold air mass settles down across the area. Surface high
pressure will begin building into the area by Wednesday night and
Thursday morning. Slackening winds and clearing from west to east
through the night will place our western valley locations in the
greatest threat freezing temperatures and frost. As the surface
high becomes more centered over eastern Kentucky thursday night
and Friday morning, subfreezing temperatures and frost will become
more likely in all of our typically colder valley locations. In
addition, deep mixing of drier air from aloft to the surface is
expected Thursday and Friday afternoon. This will likely drop
minimum afternoon relative humidities down to between 20 and 30
percent. Ensemble members in general do hint at a small signal for
lower relative humidities, and expect probabilities to increase
as we approach the window of concern. Finally, as the
aforementioned surface baroclinic zone develops and settles down
across the area, it will become the focus for thunderstorm
activity. Instability in combination with effective shear will
increase with time along this baroclinic zone. Thus thunderstorm
potential grows as we get into early next week. This overall
pattern and system are worth watching as steering winds could
become parallel at times with this zone or axis of instability and
shear. While we are dry, the potential of training could provide
some substantial rainfall amounts to portions of the area should
it materialize. Much will change between now and the end of the
extended, but again, the pattern is worth watching.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 139 AM EDT TUE MAR 26 2024

VFR conditions to begin the period as elevated showers and
possibly a few thunderstorms move across primarily KSME, KLOZ, and
KSYM through 09z. Cigs gradually lower through the remainder of
the morning as the atmosphere moistens, with all TAF sites likely
eventually experiencing MVFR conditions at some point in the late
morning through mid-afternoon period. Models also suggest a quick
partial clearing as showers end Tuesday afternoon from west to
east. Note that confidence in timing of precipitation as well as
when MVFR reductions begin and end is not particularly high.

LLWS will continue for TAF sites until more persistent shower
activity moves over a TAF site this morning. Southeast winds
generally 10 kts or less with occasional gusts to near 20 kts will
gradually becoming more southerly and then southwesterly late this
afternoon and evening.

&&

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

$$

SHORT TERM...CMC
LONG TERM...RAY
AVIATION...CMC


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