Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 291835 AAC

Area Forecast Discussion...UPDATED
National Weather Service Jackson KY
235 PM EDT SUN MAY 29 2016

Issued at 225 PM EDT SUN MAY 29 2016

Hourly weather grids were updated based on recent radar and
observation trends. However, no substantial changes were needed at
this time. The best chance convection over the next couple of
hours will be from the Big Sandy Region down to the VA border
counties. The convection will be slow moving so some locally heavy
rain will fall from these.

UPDATE Issued at 1058 AM EDT SUN MAY 29 2016

Minor adjustments have been made to the hourly grids based on
observations and radar trends. This led to a bit higher pops
across the western part of the CWA just west of JKL over the next
couple of hours where a narrow broken line of showers is moving
slowly east and lowered pops over the next couple of hours along
the VA border as moisture and showers on the outer edges of the
circulation of TD Bonnie is struggling to make it much further
west than I 77 corridor in WV and VA or into portions of NE TN.
Additional isolated to scattered convection should develop during
peak heating as a shortwave trough slowly approaches from the
west. Coverage should be a bit greater than yesterday more in the
scattered range due to some mid level forcing.

UPDATE Issued at 720 AM EDT SUN MAY 29 2016

Did a quick update to add in a potential for isolated
thunderstorms in the morning portion of the forecast. Also removed
fog from the grids and adjusted T/Td/Sky/PoPs per the latest
observations and trends. These have been sent to the NDFD and web
servers, along with a freshened set of zones.


.SHORT TERM...(Today through Monday)
Issued at 400 AM EDT SUN MAY 29 2016

07z SFC analysis shows relative high pressure over East Kentucky
early this morning as low pressure is found off to the northwest
as well as to the southeast associated with landfalling Tropical
Storm Bonnie. Mainly just some mid and high level clouds are
around the CWA - some loosely connected to the tropical system.
This is likely helping to keep the fog at bay for most places this
morning, though not enough to limit the development of a ridge to
valley temperature split. As such, readings vary from the low 60s
in the more sheltered valleys of the east to the upper 60s on the
ridges. Dewpoints, meanwhile, are in the muggy category for
another night, running from the low to mid 60s. Winds are light
and variable with a clean radar scope at this hour.

The models are in good agreement aloft through the short term
portion of the forecast. They all depict general ridge conditions
through the southeast, but one that has been hollowed out by the
arrival of the tropical storm into the Carolinas. At the same
time as the mid level energy arrives from the tropics, a trough
will brush by Kentucky to the northwest resulting in a gradual
decrease in heights for the area into Monday. Again the mesoscale
will be the more dominant driver of the weather details with the
higher resolution HRRR and NAM12 favored for forecast specifics.

Sensible weather will feature a bit of valley fog around this
morning followed by another warm day. The models suggest that the
best chances for convection will be over the eastern portion of
the CWA and that makes sense with the higher terrain helping to
initiate convection in an environment with little lower level
shear, but ample instability. The downstream influence of T.S.
Bonnie, resulting from from its broad region of uplift around its
core and areas of subsidence/enhancement spreading out from the
center, though weakening with distance, may be enough to give
the east an extra shot at convection later today. Accordingly,
have given the highest PoPs to those parts and lesser amounts to
the west. The NAM12 depicts this well and the gridded forecast -
pretty much followed suit. Another concern, affecting the area
later in the day and into the night, is a weak front sliding
southeast into the Ohio Valley possibly initiating more storms
thanks mainly to the inherent instability. This boundary could
bring isolated to scattered storms to the area well into the
night as it settles into far southeast Kentucky late tonight.
Have kept a small chance for this in the forecast along with a
potential renewal of convection in the far southeast on Monday,
while the rest of the area enjoys a pleasant, warm, and dry
Memorial Day.

Again used the ShortBlend and CONSShort as a starting point for
most of the weather elements with small to moderate adjustments
to temperatures at night for ridge to valley splits. Also, upped
temps a notch today and Monday. As for PoPs, ended up lower to
the MAV guidance thinking that the best chances will be further
east today compared to the MET offering.

.LONG TERM...(Monday night through Saturday)
Issued at 330 AM EDT SUN MAY 29 2016

The first part of the long term period will be mostly dry as surface
high pressure builds into East Kentucky Monday evening. The only
exception will be along the southeast Kentucky border where a few
afternoon showers may pop up as a cold front exits the region. The
dry, but warm weather will persist through Wednesday. Moisture and
humidity will then begin increasing again as a low pressure system
approaches the region. This system will bring a cold front into East
Kentucky by Thursday afternoon. Shower and thunderstorm chances will
increase throughout the day, as the front approaches, with the best
chance for thunderstorms mainly in the afternoon and evening. If
this ideal timing holds true, there will be a chance for at least
some strong storms. The frontal boundary may stall somewhere in the
region Thursday night through at least Friday, keeping the weather
unsettled. There is a chance that an upper level shortwave trough
will move through Kentucky on Saturday, kicking the frontal boundary
south of the area. However, confidence is low this far out in the
forecast on where the boundary will set up and for how long.

Temperatures will remain on the warm side, in the lower 80s, through
Thursday. A cold front will move through most of the region by
Thursday evening, allowing temperatures to cool down to below normal
values. This cool airmass will allow afternoon high temperatures to
stay in the low to mid 70s. Low temperatures each night will be in
the lower 60s.


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

Convection is currently working across the eastern portion of the
area. This will affect locations near SJS and also non TAF site
PBX with some brief MVFR or IFR over the next hour or two.
Otherwise, additional isolated activity is possible through
around sunset or perhaps later if any convection can manage to
develop along a rather weak cold front approaching from the west.
Outside of this, VFR is anticipated with one exception, fog
tonight into early on Monday. Since JKL received rain earlier and
SJS did as well, fog possibly into the IFR range and possibly at
least briefly below airport mins can be expected for a time in the
6Z to 14Z period. Guidance also brings generally IFR fog to LOZ
and SME and MVFR fog to SYM. Outside of any stronger showers or
thunderstorms, winds to remain light, at around 5 kts or less,
throughout the period.


.JKL Watches/Warnings/Advisories...


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