Area Forecast Discussion
Issued by NWS Jackson, KY-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS63 KJKL 260250 CCA
Area Forecast Discussion...CORRECTED
National Weather Service Jackson KY
1050 PM EDT WED MAY 25 2016
-- Changed Discussion --Issued at 1048 PM EDT WED MAY 25 2016
Lack of instability and lingering subsidence has effectively
brought an end to showers across the area this evening with the
exception of a few light showers in the southwest. Otherwise, the
shower activity has ended at least for the beginning of the
night. Later tonight towards dawn, a weak disturbance combined
with a weak low level jet may be enough for a few showers to pop
up later tonight. Models are not handling this well and lack of
instability bring up a few questions tonight. For now, went with
slight chance of showers and changed from coverage to probability.
A new zfp has been sent.
UPDATE Issued at 800 PM EDT WED MAY 25 2016
Current conditions across the area feature scattered showers and
isolated thunderstorms tracking through eastern Kentucky. Most of
this activity is on the wane as surface high pressure still just
to the west is enough to break down this activity as it moves into
the area. Have increased pops to the southwest as the incoming
area should make it into the southwest counties before
dissipating. With this...there should be a period later tonight
with no activity before another wave moves into the area just
before dawn. Updated the forecast and sent out a new zfp.
-- End Changed Discussion --
.SHORT TERM...(This evening through Thursday night)
Issued at 329 PM EDT WED MAY 25 2016
A cluster of showers, originating off the Cumberland Plateau and
currently approaching the I-75 corridor, will continue to track
northeast this afternoon. Surface-based CAPE of 500-1000 J/KG has
developed and led to an afternoon cumulus field amid a steady stream
of increasing mid to high clouds moving in from the west ahead of a
disturbance stretching from southeast Saskatchewan through the
Mississippi Valley. May see an increase in shower and thunderstorm
activity, mainly across the Bluegrass region, as this energy
propagates toward eastern Kentucky. Further development will be
possible across the higher terrain as additional low level
forcing for ascent will be nonexistent. Will see this pulse-type
activity quickly dissipate as poor deep layer shear will lead to
cold pools quickly overwhelming updrafts.
Lingering shower activity will be possible through the night as
southwest flow aloft will be characterized by microscale shortwave
impulses. Instability looks to be low enough to negate thunder
mention with a diurnally cooling boundary layer. Dewpoints in the
upper 50s to lower 60s will only allow overnight lows to fall into a
similar range as moisture from the Gulf of Mexico remains in place.
Despite mid to high cloud cover persisting, patchy valley fog will
be possible given near-surface saturation.
A similar story continues for Thursday with isolated showers and
thunderstorms developing in a weakly forced environment. Highs
rising into the mid 80s will again provide ample enough instability
for pulse storms in a weakly-sheared environment. Following any
lingering showers Thursday evening, lows in the low to mid 60s along
with patchy valley fog will once again be in the offing overnight in
a moist environment.
.LONG TERM...(Friday through Wednesday)
Issued at 332 PM EDT WED MAY 25 2016
More summer like weather will remain the story for a good portion
of the long term period. This is brought to us by a upper level
ridge that will reside along the east coast, meanwhile a upper
level closed low will be in place near the front range. This upper
level ridge will keep the trough well west of the region. The
issue here is we will reside on the periphery of this upper level
ridge. This will result in the potential for a few weak waves, but
right now models are remaining in little agreement overall. Given
no definitive lifting features will stick with isolated showers
and storms for now through much of the long term.
There is another caveat as we move into early next week focus
shifts to the tropics. There is a surface low that develops off
the Carolina Coast this weekend and then remains quasi stationary
with little if any steering flow. The NHC does paint the region in
a 50% chance for tropical development in latest outlook. The GFS
continues to and now the latest ECMWF bring a bit more moisture
into the region, as a result of the tropical system by Wednesday.
Therefore opt to introduce high chance pops along the VA border.
Also given increased moisture and summer like pattern will see the
potential for patchy valley fog in the mornings. Also areas that
see any storms would expect a better chances of fog formation
given increased moisture. Overall temps through the period will
remain above normal, with highs topping out in the lower 80s and
lows in the upper 50s to lower 60s.
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 800 PM EDT WED MAY 25 2016
Showers and thunderstorms will be across the area through this
evening before dissipating after midnight. Some showers moving into
the area early this evening will impact a few TAF sites before
finally dissipating. Locations that received rainfall this
evening may see a bit of fog develop tonight but nothing that will
sock in areas besides the normal river valleys. Another chance of
showers will move into the area towards dawn. The chance is
limited so at least put some vicinity showers in the TAFs. Winds
are expected to be light through the period.