Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 191738
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
138 PM EDT Sat Aug 19 2017

.UPDATE...
Issued at 1043 AM EDT SAT AUG 19 2017

WSR-88D is clear right now here in eastern Kentucky, with some
showers and thunderstorms well west in western Kentucky. Updated
to deal with this and update the text products to take fog out for
the morning.

UPDATE Issued at 838 AM EDT SAT AUG 19 2017

Freshened up the hourly temperatures, dew points, and sky cover
through this morning. Some light returns are popping up on radar;
however, these are most likely producing a few sprinkles at best
right now.

&&

.SHORT TERM...(Today through Sunday)
Issued at 353 AM EDT SAT AUG 19 2017

The latest surface map features high pressure generally ruling
across the mid-Mississippi Valley, with a weak quasi-stationary
frontal boundary draped across the Ohio Valley from west to east.
Aloft, a short wave trough was moving from the Midwest into the
Ohio Valley, with some mid and high level clouds moving towards
the central part of the Commonwealth.

This short wave trough will continue eastward today, bringing the
threat of a few showers or storms to the I-64 corridor. Will
maintain slight chance POPs here, with little if any activity
expected further south. Highs will be in the mid 80s.

An upper level ridge will build in across the area through the
rest of the period, bringing mostly clear skies and warmer
temperatures. Highs by Sunday will be in the mid to upper 80s,
after a night of lows similar to tonight, generally in the low
to mid 60s.

.LONG TERM...(Sunday night through Friday)
Issued at 423 AM EDT SAT AUG 19 2017

Sunday night into Monday...Eclipse day...is still shaping up
nicely with upper level ridging along and south of the region.
Both the GFS and ECWMF are going dry for the CWA now throughout
the day, with mostly clear conditions. However, the NAM12 is now
putting in some very spotty convection during the afternoon. That
being said, the model has been dry up until this point and seems
to be the outlier compared to the GFS and ECMWF with strong
surface high pressure in place...not to mention its later in the
forecast period for this model. All things considered, kept pops
below slight chances throughout the day. Temperatures will remain
above normal with the strong ridging in place, peaking in the
upper 80s both days. A few locations could top out at 90 degrees
on Monday afternoon. Adjusted the diurnal curve around mid-day to
accost for eclipse affects on temps Monday as well.

Deepening longwave troughing is expected to impact the Ohio
Valley for mid and late week. At the surface, a cold front will
push southward through the state during the day Tuesday,
increasing the SW flow across the region. The cold front will then
traverse the state Tuesday night through Wednesday morning,
exiting to our SE by Wednesday afternoon. Expect shower and
thunderstorm chances starting Tuesday with the warmer/moist
unstable flow ahead of the front, peaking in coverage Tuesday
night/Wednesday morning, then tapering off Wednesday
afternoon/evening. Post frontal conditions will likely not support
thunder, especially as we head into the overnight and a much more
stable airmass quickly moves in, so nixed any thunder mention as
of 0Z Thursday. Precip chances should taper off throughout the
overnight.

High pressure and northerly flow take hold for the rest of the
week. With troughing in place aloft, the northerly flow will be
fairly deep, and promote cooler than normal temperatures despite
sunny conditions. Highs Wednesday through Friday will be in the
upper 70s to around 80 with low humidity.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 138 PM EDT SAT AUG 19 2017

An upper level trough is swinging across the Ohio Valley this
afternoon. The lack of better moisture will lead to overall lack
of coverage for showers this afternoon and continued to keep any
mention out of the SYM TAF. Otherwise VFR conditions will be the
story, with a few afternoon CU at around 5 kft. We will see
mostly clear skies tonight and this will aid in fog development
especially in the deeper valleys. That said, did opt to go with
the MVFR fog toward 5Z at LOZ/SME and 8Z at SYM. Winds will
continue to remain light through the TAF period.

&&

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

$$

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



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