Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 300610

Area Forecast Discussion
National Weather Service Jackson KY
210 AM EDT MON MAY 30 2016

Issued at 1255 AM EDT MON MAY 30 2016

Did a quick update to the grids mainly to up the PoPs and QPF over
our northern sections through the rest of the night allowing the
weak front to sustain the current convection for the next couple
of hours before diminishing. Also, tweaked the T and Td grids
for the latest obs and trends. These have been sent to the NDFD
and web servers along with a freshened first period of the zones.

UPDATE Issued at 1047 PM EDT SUN MAY 29 2016

Isolated to scattered convection has fired up out ahead the
approaching weak cold front. A more organized complex of
thunderstorms located across southern Ohio has sent an outflow
boundary to the southeast. This will likely weaken as it pushes
towards Kentucky; however, did increase pops a bit along and north
of I-64 to account for the better areal coverage for the next few
hours. Also freshened up the hourly temperatures, dew points, and
sky cover according to the latest trends in observations.

UPDATE Issued at 807 PM EDT SUN MAY 29 2016

Convection has diminished across the area with the loss of heating
and weakening outflow boundary migration. A weak cold front
remains off to our west and this will move in later this evening
and into the overnight. Scattered convection has fired up along
and ahead of the boundary; however, by the time the forcing moves
in, instability will be on the demise. As such, have maintained
only isolated pops. Mainly adjusted the pop timing based on the
latest short term model and radar trends. Otherwise the forecast
remains on track.


.SHORT TERM...(This evening through Monday night)
Issued at 355 PM EDT SUN MAY 29 2016

As of mid afternoon, a mid level ridge extended from the Atlantic
northwest toward the Northeastern Conus with the upper level
system associated with TD Bonnie now over SC. A shortwave trough
was approaching the area from the west with another weak shortwave
nearing the Lower Oh valley from the west. At the sfc, an area of
low pressure associated with the trough was centered over NW
Ontario with a cold front trailing south into the Lower OH Valley.
Convection near the VA border has diminished over the past hour,
though locally heavy rain has occurred with some of this activity.
Meanwhile, a broken line of convection has developed along the
boundary from Ohio Southwest into parts of Western KY.

The first shortwave trough will move across the region this
evening, while the second shortwave approaches the area late this
evening and moves across the area tonight. The cold front will
also approach the area, but become more diffuse as it moves into
Eastern KY by late tonight. The upper level system and area of
low pressure associated with TD Bonnie will meander over the
Carolinas tonight.

There is low confidence in the convection near the cold front that
is expected to move into Central KY over the next couple of hours.
Much of the guidance shows the convection diminishing as it moves
into the area late this evening. Isolated to scattered convection
over the southeast part of the area should continue to diminish
over the next couple of hours although the airmass remains rather
warm and moist and marginally to moderately unstable as SBCAPE is
generally in the 750 J/KG range to about 2000 J/KG range with
slightly lower MLCAPE. Shear remains weak however and more typical
of mid summer and makes the diminishing convection possibility
seem more likely. An outflow boundary from the earlier convection
over the southeast is working west and north and could lead to
additional convection developing. Isolated to scattered pops were
used through the evening to account for the convective possibilities.
Several locations received at least light rain today and with
light winds and partial clearing or periods of clearing anticipated
fog will become a concern in locations that received rain earlier
today and the typically favored valley locations.

The rather diffuse cold front will continue to work across the
area and become ill defined by tomorrow afternoon. Additional weak
impulses in the flow could lead to isolated convection near the VA
border on Monday afternoon, but most locations should remain dry.
Sfc high pressure will build into the area late Monday into Monday
night valley fog may again become a concern.

.LONG TERM...(Tuesday through Sunday)
Issued at 253 PM EDT SUN MAY 29 2016

Forecast confidence is high on dry weather persisting through
Wednesday morning. High pressure will provide this period with
tranquil weather and low humidity.  Should be a fairly decent
stretch of weather.  High will shift east on Wednesday with return
flow strengthening. This will bring slightly better moisture into
eastern Kentucky. Models are persistent on a small chance of a
shower popping up on the high terrain in far southeast Kentucky.
Will go with a shower, but lack of forcing or trigger, will keep
activity very isolated and instability may not be enough quite yet
to warrant any thunder. Thus, will just go with a slight chance of a
shower in southeast Kentucky.  Otherwise, most areas should stay dry
through Wednesday night.

Models remain persistent on a mid level trough working east across
the great lakes and Ohio river valley on Thursday bringing a surface
cold front into the region. While the greatest forcing will remain
north...there will be a glancing shot of PVA into eastern
Kentucky...setting up the best rain chance for the upcoming week by
Thursday afternoon. While instability likely won`t be in question,
shear may be lacking to provide much of a severe threat. What shear
there is is all unidirectional, and at best might lead to a small
threat for a damaging wind gust. Overall, not looking great, but
models might be undercutting the shear given the presence of an
approaching cold front. Regardless, still something to watch for as
Thursday approaches.

Models are much more progressive with the front today, dragging it
south of the area by late Friday.  Will maintain a chance for
showers into Friday as the boundary slips south and perhaps a stray
thunderstorm in the south with some lingering instability. By the
weekend, weather looks to turn much drier and pleasant with highs
back into the 70s behind the exiting cold front. Overall, models in
decent agreement through the weekend, so confidence is slightly
higher than normal in the extended part of this forecast.


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

Scattered to numerous showers and thunderstorms will continue to
threaten the northern portion of the area through 09z as a weak
cold front passes through. Following the front, and in some cases
in the valleys ahead of it, fog will form, likely becoming dense
in the deeper valleys as well as across locations that saw more
significant rainfall. Have included a period of MVFR conditions
for most TAF locations, generally between 09 and 13z. Once the
fog dissipates, VFR conditions will return. Light and variable
winds will become northerly at 5 to 10 kts on Memorial Day.


.JKL Watches/Warnings/Advisories...


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