Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 131900
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
300 PM EDT Sun Aug 13 2017

.SHORT TERM...(This evening through Monday night)
Issued at 300 PM EDT SUN AUG 13 2017

Dry and pleasant weather will remain in place across eastern
Kentucky today and most of tonight, before an area of low
pressure finally brings showers and storms back to the area. The
latest model data, especially the NAM12 model, is suggesting that
showers and storms will move into the forecast a bit sooner than
previously thought, and be a bit more widespread. That being said,
adjusted the forecast to reflect the latest model guidance. The
best chance for showers and storms on Monday will still be during
the afternoon hours, with the rain tapering off from northwest to
southeast Monday night. The weather system that will produce our
rain tomorrow and tomorrow night is forecast to move slowly off to
the east. This proximity of this low will allow isolated to
scattered showers and storms to linger along the VA and TN borders
through late Monday night into early Tuesday morning. As far as
rainfall amounts go, the latest NAM guidance is producing the
highest totals, which are likely overdone across the forecast area
as a whole. Instead adjusted the blended model precip amounts
toward the latest NAM amounts, especially along the VA and TN
borders for Monday. In general, most locations could see around
one quarter of an inch of rain Monday and Monday night, with
locally higher amounts possible with any thunderstorms.
Temperatures should continue to run slightly below normal during
the period.

.LONG TERM...(Monday night through Saturday)
Issued at 417 AM EDT SUN AUG 13 2017

The extended portion of the forecast will be plagued by frontal
boundaries and upper level disturbances that move across Kentucky.
Aloft, a strong high pressure ridge will remain nearly stationary
over the Deep South and Gulf Coast through the majority of the
extended. A deep upper level low over eastern Canada will keep a
troughing pattern in place across much of the northeast conus,
becoming less amplified across the Ohio Valley due to the ridging
just to our south. Several shortwaves are expected to pass eastward
through this troughing pattern, impacting the state through the week
and into next weekend.

At the surface, a stationary front that will be draped W to E across
the southeast during the near term will shift back northward as a
warm front, reaching TN during the day Tuesday and then western
Kentucky by Wednesday as its parent low tracks northeast from the
Central Plains to the Upper Mississippi Valley. The warm front
should then become more N to S oriented and sweep eastward through
the state Thursday into Thursday night. Once this occurs, a cold
front extending from the same surface low (now over the Great Lakes)
will begin pushing SE toward the region, reaching mid Mississippi
Valley and northern Ohio Valley Friday, then pushing closer to the
Ohio River during the day Saturday, before finally making it across
the river and into the state during the day Sunday.

As for sensible weather, the combination of upper level waves and
frontal boundaries will make for a unsettled period. Showers and
thunderstorms are forecast mainly along the TN and VA borders during
the day Tuesday, as these locations will be closer to the frontal
boundary to our south. After this point, shower and thunderstorm
chances are forecast each day across all of eastern Kentucky as the
warm/moist airmass in place interacts with these frontal boundaries
and upper level disturbances. Pops will peak during the day Thursday
as the warm front moves through the CWA. Exact timing and extent of
coverage/severity of precip is still somewhat uncertain as it will
be based largely on the frontal position and correlation with peak
afternoon heating. Otherwise, generally partly to mostly cloudy
conditions are forecast through the extended, with some breif breaks
expected here and there, mainly during the overnight. Temperatures
will find their way back to seasonable normals (mid 80s) in the
afternoon for much of the extended, with lows in the upper 60s and
low 70s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
ISSUED AT 145 PM EDT SUN AUG 13 2017

The 18Z TAFs will feature VFR conditions and partly to mostly
cloudy skies to begin the period. LOZ and SME would be first to
see mostly cloudy skies due to the approach of an area of low
pressure from the southwest this evening and tonight. Cloud cover
will gradually increase in coverage tonight, with bases steadily
lowering to around 2.5k by the end of the period. The first lower
cloud bases of around 7K are expected to overspread the area by around
12Z Monday. Isolated showers and storms are expected to begin
affecting JKL and SJS by 16 or 17Z on Monday. Showers and storms
will be around SYM, LOZ, and SME tomorrow, but at this time it
appears they remain scattered enough to not warrant mentioning in
the TAFs at this time. Any airport that does see a thunderstorm
could experience MVFR or worse conditions. Winds should be
generally light and variable through out the period.

&&

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

$$

SHORT TERM...AR
LONG TERM...JMW
AVIATION...AR



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