Area Forecast Discussion
Issued by NWS Jackson, KY-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS63 KJKL 260727
Area Forecast Discussion
National Weather Service Jackson KY
327 AM EDT THU MAY 26 2016
Issued at 215 AM EDT THU MAY 26 2016
have already updated sky and wind through the next three forecast
periods based on new 00z model runs. otherwise, just made updates
based on blending in the latest obs. this did entail raising low
temps a bit for this morning in our se counties, where it has
been very slow to cool off during the night.
UPDATE 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.
-- Changed Discussion --(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 night through Wednesday)
Issued at 327 AM EDT THU MAY 26 2016
The extended forecast will feature well above normal temperatures,
muggy conditions, and daily chances of showers and thunderstorms.
The model data at this time is a bit sketchy on timing details of
the weather systems that might bring rain to eastern Kentucky from
Friday night through the middle of next week, so precipitation
chances were kept fairly low, in the 20 to 30 percent chance range
across the board. In general, the forecast is calling for rain
chances each day and night, with the best chance for thunderstorms
during the afternoon and evening hours. High temperatures each day
in the extended are expected to be in the low to mid 80s, with
overnight lows in the low to mid 60s.
-- End Changed Discussion --
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
ISSUED AT 215 AM EDT THU MAY 26 2016
All was quiet at the start of the period, with mainly vfr
conditions. There was some localized mvfr due to light fog.
Isolated showers and thunderstorms were occurring over central
ky and middle tn. Short range models have this area of precip
developing further east overnight. This is because of a shortwave
trough moving east, coupled with isentropic lift. Will expect
coverage to remain spotty, and have only used vcsh in the tafs
during the morning hours. Localized sub-vfr conditions will occur
because of fog and showers through the morning, but vfr should be
predominant. Can`t rule out additional showers/thunderstorms
developing with the heat of the day, but the probability looks low
at any given location, and it hasn`t been included in tafs.