Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 241859

National Weather Service Jackson KY
159 PM EST Sat Feb 24 2018

Issued at 159 PM EST SAT FEB 24 2018

Showers have persisted in the southeast, but should finally be
moving out this afternoon, leaving a general lull in activity.
POPs have been adjusted to reflect this.

UPDATE Issued at 1036 AM EST SAT FEB 24 2018

This update is mainly for POP trends. Another area of showers has
moved into our southwest counties this morning and is moving
rapidly northeast. Have used likely+ POPs to track this across.
Otherwise, a general thinning of showers is still expected today,
especially over the southern and eastern portions of the area.

There have also been a few lightning strikes with activity near
the western edge of the forecast area this morning. Forecast
soundings show weak instability today over much of the area, and a
slight chance of thunder is included.

UPDATE Issued at 757 AM EST SAT FEB 24 2018

Showers have made it in and are progressing to the northeast.
Lowered the POPs a bit in the southwest, as the more widespread
activity has already moved out of the area. Otherwise, the
forecast remains on track.


.SHORT TERM...(Today through Sunday)
Issued at 400 AM EST SAT FEB 24 2018

The latest surface map features a stationary boundary aligned
southwest from eastern Kentucky down into the Arklatex region.
Aloft, troughing remains poised across the Rockies, with deep
southwest flow streaming in across the Mississippi Valley, and
ridging still hanging in across the western Atlantic. Showers have
been increasing in coverage overnight, thanks to a low level jet
moving into the Tennessee valley.

Widespread showers can be expected through Saturday morning, as
the jet continues to advect northeast into our area. Some of the
showers will be moderate to heavy, with generally around a half
inch of rainfall for most locations between what falls through
dawn and the rest of the morning. There may be even a few embedded
thunderstorms, with some locally higher amounts of rainfall.

The stationary boundary will lift back to our north as a warm
front by late this afternoon, allowing for a lull in convection,
especially across our southeast. Some thinning of the clouds is
also expected, so have gone a little warmer on the highs, with mid
70s likely. Temperatures elsewhere will range from the mid 60s
north of I-64, to the lower 70s south.

The relative lull in the convection will last into this evening,
before a stronger cold front moves in well after midnight. Some
stronger wind gusts will be possible with any storms that hang on,
but instability continues to look weak, and the best forcing looks
to remain just off to our west and northwest. Locally heavy
rainfall will be possible, but given the progressive nature of the
front, any hydro problems should be more isolated for most

Showers will exiting on Sunday in the morning as the front exits
off to the east, with a noticeably drier air mass working in
during the afternoon, as dew points fall into the 30s and 40s.
Highs will still be well above normal, with readings ranging from
the low to mid 60s.

.LONG TERM...(Sunday night through Friday)
Issued at 350 AM EST SAT FEB 24 2018

The period will begin with a surface high pressure building east
into the Ohio Valley. However, a 500mb shortwave and departing
300mb jet streak will help to develop a surface low to our south.
Some of the moisture and showers could move into the far southeast
and kept this idea stays close to the ECMWF. Overall this should
be light and we will see drying conditions in the afternoon hours,
as the surface high firmly sets up across the Ohio Valley. This
surface high pressure and some subtle 500mb riding will dominate
through Tuesday evening. Tuesday will be quite dry in the
afternoon, so did lower the dewpoints some especially in the east.

By midweek the models really struggle with the upper level
patterns which complicate the synoptic surface features. The
initial shower activity will be the result of warm sector 850mb
jet energy on Wednesday. After this a split flow pattern develops
in the 00Z ECMWF and the 00z GFS depicts coupling of the two
streams. This leads to varying solutions regarding the evolution
of surface lows, with much different timing from these two models.
The ECMWF has shown the most change this cycle given the two
different pieces of energy versus the more coupled system seen in
the previous run. Therefore could not see putting all the stock
into the latest ECMWF. However,I did lean on the model blended
POPs, but capped these at high likely given the varying solutions.
Also opted to lean toward the lower QPF presented by WPC as a
result of the varying solutions. The differing solutions will also
have implications on temperatures, with the GFS showing sounding
profiles that would support at least a mix of snow Thursday night.
That said, thought the model blend solution capping temperatures
in the 40s for lows at most locations on Friday morning was the
best approach. This will keep snow out of the forecast besides
Black Mountain until better agreement can be had by the various
model suites.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)

Conditions varied widely at the start of the period, with VFR at
many places near the VA border, but VLIFR north of I-64, and
variety in between. Showers were occurring in many locations. The
differences were due to a frontal boundary bisecting the area
from SW to NE. The front is expected to lift north this afternoon
and evening, and conditions should improve to VFR everywhere, and
a lull in the precipitation is expected. Late tonight a cold front
will push through from northwest to southeast and will bring a
round of gusty showers with sub-VFR conditions. This will exit to
the southeast on Sunday morning, and VFR conditions with lighter
winds will return before the end of the period.


Flood Watch through Sunday morning for KYZ044-050>052.



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