Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 232324
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
724 PM EDT Wed Aug 23 2017

.SHORT TERM...(This evening through Thursday night)
Issued at 256 PM EDT WED AUG 23 2017

High pressure will build east over the region and continue to
influence our weather through Thursday night. This will keep skies
generally clear with light winds. The drier air has been a bit
slower than anticipated to work into eastern Kentucky today and
given the higher than expected moisture going into tonight, we can
expect to see some pretty robust fog development in the valleys
tonight. Fog will likely become dense at times in the valleys and
will toss in a mention into the HWO. While drier air should mix
down tomorrow afternoon, should still see some pretty decent fog
again for Thursday night, which is not all that uncommon for this
time of year. Overnight lows each night will dip into the 50s, but
the cooler night will likely be Thursday night with the drier air
in place going into the overnight period. This could allow us to
threaten a few record lows Thursday night.

.LONG TERM...(Friday through Wednesday)
Issued at 325 PM EDT WED AUG 23 2017

The models, with the exception of the CMC, are in pretty good
agreement with the longwave pattern aloft through the extended
portion of the forecast. They all depict the broad northeast trough
slowly easing away from the area while troughing associated with
`Harvey` moves onshore over the western Gulf of Mexico through the
start of the weekend. This will place eastern Kentucky under the
influence of northwest flow with only weak bits of energy passing
through in the mid levels. Additional troughing will take shape to
the northwest of the area at the start of the new work week while
most models keep the upper low associated with Harvey`s remnants
stuck to the Texas coast. This becomes the main concern and
confidence crusher in the forecast going forward. Should `Harvey`
remain in place - woe to the western Gulf Coast - Kentucky will be
shielded from its influence by building heights locally. That is,
at least until the developing upper low from the west moves
closer as we head deeper into the week - perhaps luring more of
Harvey`s upper support northeast into the Lower Mississippi Valley
and Deep South. However, with the agreement of the GFS and ECMWF
will lean toward the idea that through the extended the core of
the tropical storm remains to our southwest and hold off its major
impacts on our weather.

Sensible weather will feature beautiful weather through at least
Sunday with cool temperatures for this time of year and limited
showers or thunderstorm chances as sfc high pressure holds on over
the area. The forecast gets more murky for Monday through Wednesday
with shower and thunderstorm chances still mainly driven by the
diurnal cycle. However, this could change dramatically if the upper
low to the southwest actually gets picked up and starts to move east
sooner than the blends suggest. Heavy rains from this are still a
concern for the area in the latter part of the forecast, though the
models are favoring a less impactful scenario.

Made mainly mostly terrain based adjustments to the lows each night,
though the higher PoPs later in the forecast should limit the ridge
to valley differences. Also, adjusted the PoPs to gear them more
toward a diurnal cycle than initially represented by the
SuperBlend.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
ISSUED AT 724 PM EDT WED AUG 23 2017

An area of surface high pressure will continue to build across
eastern KY tonight. This is leading to general NW flow and some
drier air continues to spill southeast. The mostly clear skies
will combine with above elements for fog development especially
in the valleys and some of this could be dense at times. That
said, did opt to keep IFR to MVFR fog at most sites toward dawn,
with SJS the lowest given the tendency for lower VIS in northerly
flow patterns. This will lift around 13Z to 14Z for most and VFR
conditions return for all sites through the rest of the period.
The winds will remain light and generally northerly flow.

&&

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

$$

SHORT TERM...KAS
LONG TERM...GREIF
AVIATION...DJ


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