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fxus63 kjkl 272059 

Area forecast discussion
National Weather Service Jackson Kentucky
459 PM EDT Mon Mar 27 2017

Short term...(this evening through Tuesday night)
issued at 440 PM EDT Monday Mar 27 2017

A shortwave trough is expected to dampen as it moves into the Ohio
and Tennessee Valley regions through tonight and then across the
Appalachians on Tuesday morning and then the eastern Seaboard by
the end of the period. At the same time, a surface low will track
near or north of the Ohio River through this evening and tonight
and then into the mid Atlantic states through the end of the
period. Height rises and mid and upper level ridging area expected
behind the shortwave with surface high pressure nosing into the Ohio
Valley on Tuesday night.

Isolated to at times scattered convection continues to move
across parts of central and eastern Kentucky in advance of more
organized convection over western and west central KY and western
and middle Tennessee. This earlier convection has produced some hail
across the region and marginally severe hail and some wind would
appear to be a threat over the next couple of hours. MLCAPE of 500
to 1000 j/kg over the far south and MUCAPE of 500 to 1000 j/kg
across the area combined with 35 to 40kt of 0-6km shear would
support this although much of the area has been worked over and
the southwest part of the area should be the first to destabilize
again per rap and model forecasts though much of the western part
of the County Warning Area is expected to reach ml or MUCAPE near 1000 j/kg for a
time in the west. Satellite trends would also support another
window for heating in the south. The far southwest counties remain
in a Severe Thunderstorm Watch through 3z. Trends will continue to
be monitored for severe thunderstorm chances further east, but
much of this area has received convection this evening or in the
case of the Virginia border counties has lower sfc dewpoints due to
downsloping effects.

Some of the convective allowing models bring the convection into
east Kentucky around 23z to 01z but weaken the eastern line segment as
this will near sunset and boundary layer should begin to
stabilize. The models generally take the westernmost line east or
southeast with the recent hrrr runs favoring southeast while some
previous runs brought some of that convection more toward Lake
Cumberland. However, pending strength of cold pool, the first more
northern line segment of convection may not weaken as quickly as
models project as it moves in. Wind appears to be the primary
threat with any of this convection with bowing line segments and
possibly marginal hail from the strongest updrafts. Locally heavy
rain will also be possible if storms could train in an area.

Chances for thunderstorms will begin to diminish overnight with
shower chances also decreasing late as well as the surface low
tracks into the mid Ohio Valley and the cold front works into the
area and the axis of the 500 mb trough approaches. Chances for
convection will decrease through the day on Tuesday as the trough
and low pressure system exit to the east and northeast and mid and
upper level as well as sfc high pressure begin to build in. Low
level moisture is expected to linger well into Tuesday night, but
if the low clouds thin, radiational fog will be possible and
subsidence could bring some stratus build down late Tuesday night.

Long term...(wednesday through monday)
issued at 310 PM EDT Monday Mar 27 2017

The extended period should once again feature good chances for
showers and thunderstorms from late Thursday morning through early
Friday evening. The trigger for this activity will likely be a
slow moving area of low pressure that is progged to move across
the Tennessee and lower Ohio Valley regions. The slow forward
motion of the system should keep rain in eastern Kentucky through
Saturday morning. Thunderstorm chances should come to an end
around 0z Saturday, as the best upper level support and overall
lift should be east of the area as the low pressure system moves
off to our east. The rain should begin quickly tapering off
around dawn Saturday morning, with the rain being completely out
of the area before noon on Saturday. The weather should remain dry
from Saturday afternoon through late Sunday night, as an area of
high pressure settles over the region. Our next round of rain
could move into eastern Kentucky very early Monday morning, but
due a lot of uncertainty still exists that far out in the period.

Temperatures will continue to run well above normal, with daily
highs ranging from the mid to around 70 on most days. Thursday
looks to be by far the warmest day, with forecast highs on that
day in the 70s. Nightly lows should generally be in the 40s and


Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 230 PM EDT Monday Mar 27 2017

Showers and some thunderstorms will affect jkl and sjs early in
the period per recent radar and short term model trends.
Otherwise, a thunderstorms in the vicinity will suffice at the remainder of the taf sites
through the period as a low pressure system and upper level trough
approach. More organized convection is expected to arrive 22z to
23z in the west near sme and then move across the area through 6z
to 8z. This will at least lower conditions to MVFR if not IFR for
a while during the 6z to 18z period as the lower levels saturate.
Thunderstorms could also produce gusty winds and lower visible at the
taf sites, between 22z and 4z, but confidence in this timing is
not high enough to include attm. Once the MVFR or IFR develops
during the 6z to 12z period, it should linger through the end of
the period.


Jkl watches/warnings/advisories...


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