Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 260840

National Weather Service Jackson KY
440 AM EDT Sun Mar 26 2017

.SHORT TERM...(Today through Monday)
Issued at 439 AM EDT SUN MAR 26 2017

A weakening stacked low pressure system is centered in the
vicinity of Quincy, IL and Burlington, IA early this morning. The
mid/upper level portion of the system has a trough axis extending
southeast to the Gulf of Mexico. As the trough moves northeast,
it is interacting with a moist flow of air off the Gulf, resulting
in a large area of showers. The leading edge of showers is over
the southwest part of the JKL forecast area early this morning,
heading east northeast. The area of showers will make its way
across the rest of the forecast area this morning, and the back
edge will exit into WV around mid day.

There is no change in surface air mass taking place with this
round of precip. However, there are colder temperatures aloft
behind the leading band of precip. This has resulted in scattered
showers and a few thunderstorms during the night over western KY
and West TN. As the regime shifts eastward today, forecast
soundings show instability developing to support showers and
thunderstorms here. Uncertainty exists in the extent of coverage.
While everyone should see rain out of the leading band of precip
coming through early, that may not be the case in the afternoon.
Whatever showers/storms do occur will be on the decline and
moving out to the northeast with the upper level system tonight.

Another surface low pressure system and an associated wave aloft
will move northeast toward the Ohio valley on Monday. This will
bring with it another increase in showers and thunderstorms, aided
by diurnal destabilization. The peak in activity will likely come
on Monday evening, beyond the short term period.

.LONG TERM...(Monday night through Saturday)
Issued at 439 AM EDT SUN MAR 26 2017

One of a string of upper Level waves that is moving into the Four
Corners region this morning based on the 00Z 500mb analysis will
bring a decent shot of showers and thunderstorms for the beginning
of the period Monday night. This wave will induce a surface low
across the Central Plains by tonight and eject into the Ohio Valley
Monday night. Models seem to be handling this well and feel more
confident in this versus much of the rest of the long term portion
of the forecast. Tuesday the system will continue to progress east
and trim POPs through the day from west to east. Models are in
decent agreement with the drying period from Tuesday night into
Wednesday night. While there is some amplitude differences with the
upper level ridge and height rises think there is enough to keep the
region dry. This also coincides with the NAEFS relative min in PWATs.

Beyond this models become quite convoluted and begin to diverge in
their respective solutions. The 00Z GFS wants to bring a more
positively to neutral tilted closed low east out of the Plains by
Thursday night and the 00Z ECMWF bring a more neutrally to slightly
negatively tilted trough with more of a northern stream influence by
the same time frame. This seems to be a phasing issue and these two
solutions will have implications on the surface features as well.
There also remains a reasonable amount of spread in the GFS ensemble
mean in regards to the upper level feature and spread in the
individual members with regards to low placement hints previous
statement. Even given some uncertainty the fact that both solutions
would bring a decent shot of showers and perhaps some thunderstorms
went with likely POPs from west to east from Late Thursday into
Friday evening. The blend wanted to go CAT POPs but felt like
uncertainty would be too much for that bullish of POPs. This system
pegged to move into the Mid Atlantic and therefore a period of
drying will resume Saturday. Overall the period will be met with
well above to above average temperatures.


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

VFR conditions prevailed across the JKL forecast area at the
start of the period. An area of rain extended from southern IN and
central KY south toward the Gulf coast. While individual
cells/elements were moving northward, the entire area was slowly
shifting eastward. This leading edge of precip was currently
arriving around KEKQ, and will cross the JKL forecast area from
west to east this morning. A period of MVFR can be expected with
the precip in most areas. It will taper off to scattered showers
from west to east between about 12Z and 17Z. A resurgence of
precip may occur with heating/destabilization this afternoon, with
some thunderstorms also possible. Poor conditions can briefly be
expected in any showers and thunderstorms this afternoon and
evening, but outside of the precip VFR should prevail. The showers
and thunderstorms will diminish tonight.

Winds will pick up from the south to southwest during the day,
with gusts around 20 kt.




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