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Area forecast discussion 
National Weather Service Jackson Kentucky
1030 PM EDT Thursday Aug 25 2016

Update...
issued at 1030 PM EDT Thursday Aug 25 2016

Infrared Sat showing a few high clouds moving across the Lake Cumberland
region, but otherwise clear skies for most. Just minor tweaks to
the grids with latest obs and trends in mind.

Update issued at 706 PM EDT Thursday Aug 25 2016

WSR-88D radar showing the afternoon convection has diminished and
this is in line with the forecast grids. Otherwise we are looking
at a warm and humid evening under the upper level ridging and
return flow at the surface. Grids are on track and only overnight
issue will be valley fog potential. Therefore only minor tweaks
needed for current conditions tonight in the grids and taking the
thunder out of the severe weather potential statement.

&&

Short term...(this evening through Friday night)
issued at 348 PM EDT Thursday Aug 25 2016

Upper ridging across the Tennessee Valley will edge northeast
into the Appalachians and mid-Atlantic Friday into the weekend,
keeping a hot and humid airmass in place across eastern Kentucky.
This airmass has led to isolated shower and embedded thunderstorm
activity this afternoon along a weak moisture gradient. Will see
these diminish into late afternoon as this gradient and subsequent
low level forcing decrease. Decay of diurnal cumulus field and
increasing subsidence will allow for patchy fog development
tonight and Friday morning, especially in sheltered valleys. An
influx of relatively drier air coupled with another generally
precipitation free day should limit more widespread development.

Deep layer subsidence, stemming from the above mentioned upper
ridge moving overhead, and a lack of forcing for ascent should
lead to a dry Friday. An upper shortwave trough and weak cool
front look to remain confined to the Ohio Valley and north as
ridging holds strong locally. Best chance of any development would
be off the Cumberland Plateau and higher terrain along the
Virginia border, but a Theta-E minimum in place along with
subsidence aloft should preclude mentionable chances. This will
allow for a hot afternoon as temperatures soar into the upper 80s
to lower 90s.

Long term...(saturday through thursday)
issued at 348 PM EDT Thursday Aug 25 2016

Not the best agreement amongst the extended this time around. The
European model (ecmwf) was consistently drier through out the period than the GFS.
The blended model data settled around a solution that features
showers and storms moving into the area Saturday afternoon, and
persisting Monday afternoon, with the most active periods being the
afternoon and evening hours. It then appears that a ridge of high
pressure will settle over the area from Monday evening through
Tuesday morning, bringing a brief respite from shower and storm
activity. A sluggish cold front will attempt to push into the area
from early Tuesday afternoon Onward. This boundary may spark a few
showers and storms in our far western counties on Tuesday. After
that, another ridge of high pressure is progged to spread over the
area Tuesday evening and early Tuesday night. More showers and
storms are then expected to plague the area from late Tuesday night
through the end of the week. With the amount of uncertainty in the
model data, decided to keep only very low rain chances in the
forecast, at least until the models have a better handle on things.

Hot and muggy conditions are expected to persist through out the
period, with highs around 90 expected from Saturday through
Wednesday. The expected clouds and precipitation should allow
temperatures on Thursday to not be quite as warm, with highs in the
mid to upper 80s on that day.

&&

Aviation...(for the 00z tafs through 00z Friday evening)
issued at 733 PM EDT Thursday Aug 25 2016

Most sites will enjoy VFR taf period. Any convection that
developed through the day has now diminished and we are left with
some cumulus at a few sites to begin the period. Think this will wane
through the evening and we will be left with high clouds at best.
That said the increase in moisture will stand to see valley fog
issues overnight into the morning. The question will be if this
can be seen at any sites and right now loz stands the best chances
given a more persistence. Therefore kept this thought of MVFR visible
for both sme and loz given the usual issues, however not buying
into the degradation seen in some of the guidance at this point.

&&

Jkl watches/warnings/advisories...
none.
&&

$$

Update...dj
short term...Guseman
long term...Arkansas
aviation...dj

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