Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 131112
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
712 AM EDT Sun Aug 13 2017

.UPDATE...
Issued at 711 AM EDT SUN AUG 13 2017

Latest sky cover from satellite imagery has been blended into the
forecast grids this morning. Temps in the north also got a bit
cooler than expected, and this was accounted for in the morning
temperature curve. |

&&

.SHORT TERM...(Today through Monday)
Issued at 417 AM EDT SUN AUG 13 2017

A cold front has moved/transitioned to our southeast. Drier air
has started its way in from the north, but is having trouble
displacing surface moisture, especially in our southern valleys.
As a result, fog has again developed. The fog will disperse in the
morning. Otherwise, high pressure passing to our north behind the
front will be our dominant influence today and tonight, bringing
fair weather.

The high will move to our east on Monday and winds around it will
start to carry moisture back northward. At the same time, a weak
shortwave trough aloft is expected to track over the area. The
combination may bring a return of showers and thunderstorms,
especially near the TN and VA borders.

.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 12Z TAFS through 12Z Monday morning)
ISSUED AT 711 AM EDT SUN AUG 13 2017

Low ceilings in the 1-2K ft range were still present in the far
southeast part of the forecast area early this morning. Fog has
also developed adjacent to many of the deeper valleys across the
area, bringing localized VLIFR conditions. As of 11Z, KSJS was the
only TAF site being impacted. The low clouds and fog will
dissipate this morning, leaving VFR conditions to last until late
tonight. Fog should once again develop in valleys and then spread
in breadth and depth. More TAF sites could be impacted toward dawn
on Monday, but there is uncertainty as to the extent.

&&

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

$$

UPDATE...HAL
SHORT TERM...HAL
LONG TERM...JMW
AVIATION...HAL



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