Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 310636 AAC
AFDJKL

Area Forecast Discussion...UPDATED
National Weather Service Jackson KY
236 AM EDT SUN JUL 31 2016

.UPDATE...
Issued at 217 AM EDT SUN JUL 31 2016

Hourly grids for the overnight hours have been adjusted based on
observation, satellite, radar,and observation trends. The threat
for at least a stray shower or a thunderstorms cannot be ruled out
the entire night, particularly across the southern half to two
thirds of the area. This thinking is supported by satellite,
radar, and recent HRRR runs and other convective allowing models.
Fog should also develop where significant breaks in the low and
mid clouds occur and in locations that received rain on Saturday.

UPDATE Issued at 1055 PM EDT SAT JUL 30 2016

Have adjusted the near term grids per the latest obs and radar
data. Will be keeping a small chance of a thunderstorm through the
night given the frontal position and old outflow boundaries, as
well as, the latest HRRR guidance. These grids have been sent to
the NDFD and web servers. An updated HWO and ZFP will be issued
shortly.

UPDATE Issued at 730 PM EDT SAT JUL 30 2016

23z SFC analysis shows eastern Kentucky just southeast of a
stalled front with plenty of warm and moist air in place. This has
led to a continuation of scattered convection into the evening
hours with the latest cluster entering the I-64 to Mountain
Parkway corridor. This will progress steadily east through the
first part of the evening with a left over outflow boundary
anticipated and a potential for further development, though
limited by diurnally falling instability, into the night with
small chances continuing for most of the area into dawn. Based on
this, and the latest high resolution guidance from the HRRR, have
adjusted PoP/Sky/QPF/Wx through the rest of the evening and into
the night. Temperatures, meanwhile, are in the upper 70s and lower
80s most places while dewpoints hold near 70s degrees along with
light and variable winds outside of the northern area of storms
where winds are generally from the northwest at 10 to 15 mph. Do
anticipate the development of patchy fog in the valleys and in
places that see rain this evening. Look for a very small ridge to
valley temperature split tonight given the moist environment and
some clouds around. The grids have been updated to reflect this,
as well. These have been sent to the NDFD and web servers.

&&

.SHORT TERM...(This evening through Sunday night)
Issued at 308 PM EDT SAT JUL 30 2016

WSR-88D radar continues to show a few showers continuing to
develop across portions of the CWA this afternoon. These could
expand a bit more in the northern portion of the CWA as storms
move east out of northern central KY. This has been brought on by
a weak upper level wave and a surface boundary near the Ohio
River. This is being handled fairly well by the CAM data and SSEO
and therefore have blended close to these short term models for
pops. Coverage wise these should be mostly diurnally driven but
given the cyclonic flow will keep at least slight pops overnight.

Sunday best pop coverage will reside in the southern portions of
the CWA. This given less of a focus lifting wise within the upper
level pattern and the column lessen moisture wise given PWATS
finally drop into the 1.5 range. Therefore overall went toward a
more diurnal and topographical type scenario. Given the lessening
moisture going into Sunday night do actually expect that most
areas should see a end to the stormy activity for a change.
Temperature wise would expect most locations will remain near
normal through the period.

.LONG TERM...(Monday through Saturday)
Issued at 345 PM EDT SAT JUL 30 2016

Somewhat deamplified troughing will be in place across the Ohio
River valley to start off the day Monday. A weak shortwave will
pass through this trough during the day Monday as the troughing
begins amplifying due to building high pressure over the
southwest conus. The upper level pattern will remain nearly
stationary through the day Tuesday, as the upper level high slowly
pushes into KY Wednesday through the remainder of the week. A
strong upper level low passing across Canada late in the week and
through the weekend may cause heights to lower once more for the
weekend.

With the presence of the trough in place across the region, a cold
front will also find itself draped across the state Monday. This
frontal boundary will push slightly southward late in the day
Monday, while still encompassing the western portion of the
state. This boundary will become nearly stationary through
midweek, and then will finally start to break down Thursday as
the upper level ridge moves into the region. The above mentioned
upper level low that will be traversing Canada into the weekend
will also produce a surface low pressure system. This will contain
a long surface frontal boundary, expected to swoop southward and
along the Ohio River by Friday night, then remaining nearly
stationary into Saturday.

With the frontal boundary in place through much of the workweek,
and temperatures expected to warm into the mid and upper 80s each
day, expect the available instability and lift to spawn showers
and thunderstorms each day, peaking during the afternoon/early
evening with warmest temps. Coverage is still somewhat sporadic
across the models, and without any strong forcing, did not see
need to go above slight chance to chance pops each day. The
exception will be the very end of the period, specifically
Saturday, when the stronger cold front is expected to enter into
the region and may bring about more numerous shower and
thunderstorm coverage. Also...after this Monday, winds will
become fairly light in the mid and upper levels, so storms may be
slow moving and pulsy. In good news, however, the PWAT values
will be within tolerable values (well under 2 inches), so not
expecting any further flooding concerns (unless of course training
of storms over a specific location for a period of time occurs).

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
ISSUED AT 220 AM EDT SUN JUL 31 2016

Isolated convection continues to move across southern portions of
the CWA and this may be in the vicinity of SME, LOZ, and JKL over
the next few hours. The other concern is low stratus and fog
development which is highly dependent on low and mid clouds and
where rain has fallen over about the past 12 hours. For now, we
have kept sites mainly in the MVFR range for vis restrictions
from around 9z to about 13Z due to uncertainty, but in line with
guidance. Guidance had a period of IFR at SME and generally
followed this. Outside of any convection, winds will remain light
and variable. Convection on Sunday will be highly variable, as
well, with LOZ and SME having the highest chances, but also
possible at JKL and SJS. Accordingly, have included a VCTS for a
time after 16Z for those sites.

&&

.JKL Watches/Warnings/Advisories...
None.
&&

$$

UPDATE...JP
SHORT TERM...DJ
LONG TERM...JMW
AVIATION...JP



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