Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 250815

National Weather Service Jackson KY
415 AM EDT Fri May 25 2018

.SHORT TERM...(Today through Saturday)
Issued at 415 AM EDT FRI MAY 25 2018

07z sfc analysis shows high pressure having shifted off to the
east while weak low pressure exists to the south and west of the
area. More clouds have moved through the sky over eastern Kentucky
this night helping to slow the fog developing in the river
valleys - thus far. They did not prevent another ridge to valley
temperature split from developing overnight with readings
currently varying from the low 60s in the sheltered spots to
around 70 on the hills. Dewpoints are up over last night with
values generally in the lower to middle 60s. Winds are light and
variable where they are not calm ATTM.

The models remain in good agreement aloft through the short term
portion of the forecast. They all depict a weakening ridge of
heights over Kentucky this night with a trough approaching from
the northwest. This trough brings with it more in the way of
energy that will strafe by the state into the weekend. At the
same time, an upper low will continue to take shape over the Gulf
of Mexico with its lower heights helping to draw the effects of
the mid level trough more into our area by Saturday. Given the
good agreement among the guidance, will favor a general blend
with a lean on the higher resolution HRRR and NAM12 for finer
scale convective details through the period.

Sensible weather will feature a return of humid and likely stormy
conditions through the start of the weekend. Moisture increasing
from the south and plenty of instability developing will probably
lead to scattered convection developing over the higher terrain
late this morning and into this afternoon. With this, some
expansion back northwest to the rest of the CWA is anticipated.
The convective activity today will be diurnally driven and tail
off with sunset. Higher moisture content and more clouds around
will lead to more uniform temperatures tonight, except maybe in
the sheltered valleys in the northeast where decoupling could
occur, though shower and storm activity may move back in from the
west toward dawn, per the NAM12. Accordingly, expect less in the
way of fog around tomorrow morning for most spots. On Saturday,
the approach of the upper trough and more mid level energy passing
to the north expect to see better coverage of still primarily
diurnally driven showers and thunderstorms. Through this time, PWS
in the range of 1.5 to 1.8 inches suggest a potential for heavy
rains should the showers and storms sit in one place or train very
much. Forecast soundings do indicate that the convection should
be progressive enough to limit this concern, for now.

Again used the CONSShort and ShortBlend as the starting point for
all the short term grids. Did not adjust temperatures much
through the period aside from point specific values and in those
northeast valleys tonight. For PoPs, though, did significantly
raise up the values from the CONSShort through the period owing to
the better chances depicted in both the HRRR and NAM12.

.LONG TERM...(Saturday night through Thursday)
Issued at 300 AM EDT FRI MAY 25 2018

The extended will feature periods of showers and thunderstorms, with
the best chances for storms during the afternoon and evening hours
each day. The wild card during the period will be a possible
tropical system that the models are trying to form at some point.
There is a lot of uncertainty as to when this system may form and
what track it will follow. If this tropical system does indeed form,
which the National Hurricane Center web page is predicting it will,
the track and strength of the remnants of this system may or may not
have some influence on the weather of eastern Kentucky at some point
next week. That being said, generally went with a slightly modified
version of the model blend for precipitation chances and the timing
of precipitation across the area for the middle of next week. In
general, showers and storms will be occurring each day in the
extended, as a series of non tropical weather systems move across
the Ohio and Tennessee valley`s. Temperatures will continue to run
above normal, with daily highs topping out in the low to mid 80s,
and nightly lows in the mid 60s.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)

Light winds and VFR conditions will be seen for most of the area
through the aviation period. However, some patchy valley fog will
develop in the valleys through early this morning. However, this
should not impact the TAF sites. Scattered thunderstorms will then
develop later in the afternoon and could approach some of the
airports so VCTS has been included in the TAFs for this cycle.




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