Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 200819
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
419 AM EDT Thu Jul 20 2017

.SHORT TERM...(Today through Friday)
Issued at 417 AM EDT THU JUL 20 2017

Upper level ridging will continue to build into the region today.
It will dampen somewhat tomorrow in the northern portion of the
state as a strong upper level low over Hudson bay allows for more
WNW to ESE flow across the northern half of the U.S. to shift a
bit southward into the northern Ohio Valley. That being said, even
with this small shift, the upper level ridge will still have
dominant control.

At the surface, high pressure will also be large and in charge
across the state today. The continued building heights will
attribute to yet another day of well above normal temperatures,
reaching 90 or maybe even topping it in most locations. A few fair
weather cu will be possible during the afternoon, but otherwise
conditions should remain dry under this regime. By Friday,
however, a cold front will push towards the region from the north.
Flow will become more S to SW, allowing more moisture to advect in
from the south and boosting humidity levels a bit (though not a
strong surge). This will cause two concerns. First, the presence
of the frontal boundary just to our our north and a warm/more
humid airmass in place, could spark isolated to scattered showers
and thunderstorms during the day, especially in the afternoon.
Best chances will be in the northern CWA and along the high
terrain in the SE. Second, the S/SW flow will boost temps another
degree or two, into the low 90s for highs. This will combine with
the additional humidity in the atmosphere to produce heat indices
just over 100 degrees in most locations. While we are still below
heat advisory criteria based on the forecast, will go ahead and
issue an SPS for heat concerns this day.

.LONG TERM...(Friday through Wednesday)
Issued at 255 PM EDT WED JUL 19 2017

We will remain under the influence of mid/upper level ridge
through Saturday which means more of the same with heat and
humidity staying around. A stray afternoon shower or storm is
possible, but coverage will likely remain at or under 5 percent
areawide.

Better rain chances look to return on Sunday as a weak cold front
inches southward across the area during the day. Still some
question as to the aerial extent of the showers and storms as
forcing will remain weak. Shortwave trough will then swing east
across the great lakes early next week, but the better forcing
with that trough will remain to our north. However, it could help
to refocus convection along the slowly moving front as it slow
pushes southward. Thus, it looks like rain chances will continue
through Monday.

Tuesday and Wednesday will see a return to slightly cooler
weather behind the exiting front. However, depending on where the
front dissolves, some moisture could linger to provide a
lingering shower into the midweek period, especially in the south
or southeast. Still lots of uncertainty on this potential.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
ISSUED AT 151 AM EDT THU JUL 20 2017

Surface high pressure and an upper level ridge building into the
area will continue the rather stagnant weather pattern, with VFR
conditions and light winds prevailing through the period. Fog will
develop in the river valleys once again late tonight, dropping to
MVFR or IFR restrictions by near daybreak. As fog lifts near
daybreak, there is still a chance that SME could once again be
affected, as has been the case for previous mornings. However,
impacts have also shown a decreasing trend thanks to continued
drying, so actually not confident enough of the fog being
impactful enough to even include in the SME TAF. Once fog
dissipates across east KY Thursday morning, expect mostly clear
skies with mainly just diurnally driven CU developing in the
afternoon, generally around 4k ft.

&&

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

$$

SHORT TERM...JMW
LONG TERM...KAS
AVIATION...JMW



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