Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 230220
AFDJKL

Area Forecast Discussion
National Weather Service Jackson KY
1020 PM EDT SUN MAY 22 2016

.UPDATE...
Issued at 1020 PM EDT SUN MAY 22 2016

Radar trends indicate that the boundary layer has finally begun
to stabilize. Updated the forecast package to remove thunder. Also
took the opportunity to freshen up the zones and to lower
overnight lows slightly...mainly for a few spots in our east.
Hourly obs are already showing temps approaching advertised lows
in a few locations. Very dry air has managed to settle into the
area with afternoon dew points dropping into the lower to mid 40s
and this will help mitigate overnight fog potential. Dew points
are higher in areas that saw rainfall this evening and as such
expect any overnight fog to develop in these areas first. Would
also expect those areas that received rainfall may even see some
locally dense fog. However, attm felt threat wasn`t widespread
enough to highlight but will monitor and pass on any concerns to
incoming shift.

UPDATE Issued at 822 PM EDT SUN MAY 22 2016

Convection continues to fire this evening across mainly our
eastern most counties. High res, short term models do not show
any definitive decrease in activity until after sunset. Based on
current radar trends this seems reasonable. Current forecast has
everything handled well. Updated grids to bring them in line with
hourly trends. No updates to the zones attm.

&&

.SHORT TERM...(This evening through Monday night)
Issued at 330 PM EDT SUN MAY 22 2016

19z SFC analysis shows low pressure just off to the east of
Kentucky with high pressure building in from the west. This high
is bringing some drier air to eastern Kentucky, but not quick
enough to prevent the formation of instability CU and some light
showers in the far east. Thunder has developed further east in
West Virginia with some healthier showers. The latest near term
models still predict some convective development in the far east
through the first part of the evening. Plenty of sunshine at the
start of the day, until the CU developed, helped send
temperatures into the low and mid 70s across the area this
afternoon. Dewpoints mixed down into the low to mid 40s most
places, as well. This deep mixing is allowing some gustiness to
develop with the northwest to north winds over the western parts
of the CWA where gusts are reaching to between 15 and 20 mph.
Elsewhere, northwest winds of around 10 mph are common.

The models are in good agreement aloft through the short term
portion of the forecast as they all pivot the eastern trough
southeast and off the coast of North Carolina by midday Monday.
This now closed low then lifts north along the coast into Tuesday
morning while heights rebound for Kentucky and even some ridging
works into the western parts of the Ohio Valley. Given the model
agreement have favored a general blend for weather details with a
lean toward the HRRR and NAM12 this evening and on through the
night.

Sensible weather will feature a small chance for scattered showers
and stray thunderstorms over the far eastern tip of Kentucky
through sunset. Otherwise, skies will be mostly clear overnight
facilitating the development of a small to moderate ridge to
valley temperature split along with valley fog - locally dense.
The fog may become more extensive in the far east for places that
manage to see any rain in the late afternoon/early evening. For
Monday, another great day of weather will be on tap with
temperatures hitting the low to mid 70s again along with
comfortable humidity levels and plenty of sunshine for most of the
area. Look for some extra clouds around in the far east as the
high will only make limited progress east into Monday and more CU
is expected to develop there by mid to late afternoon. Expect a
similar night Monday night to tonight with another moderate ridge
to valley temp split on tap along with patchy valley fog, probably
less extensive than Monday morning thanks to another full day of
drying.

Again started with the ShortBlend for most elements of the
forecast with some terrain adjustments to temperatures both
tonight and Monday night for ridge to valley splits. During the
latter part of the forecast the SuperBlend was used as the init
with only minor adjustments to sky cover and temps/dewpoints.

.LONG TERM...(Tuesday through Sunday)
Issued at 400 PM EDT SUN MAY 22 2016

Broadening and deamplifying upper ridging will move overhead Tuesday
as a surface ridge slides across the southern Appalachians toward
the Atlantic coast. A continued warming trend will ensue as highs
soar into the upper 70s to lower 80s as a dry airmass remains in
place.

An upper low across lower Alberta and Saskatchewan into the
northern U.S, with an associated trough extending through the
intermountain west into the Great Basin, will then begin to nudge
eastward by midweek. Backing flow aloft along with leeside
cyclogenesis across the Great Plains will bring a steady dose of
return flow into eastern Kentucky. Showers and thunderstorms will be
possible as early as Wednesday morning across the Bluegrass region
into the Lake Cumberland region, but will likely hold off until
later in the afternoon or evening when a shortwave impulse
approaches the region. May very well see additional waves or changes
in the timing to this one which could spark scattered storms
Wednesday given warm sector positioning.

Storm chances will continue through the remainder of the week into
the weekend with a stagnant airmass in place, but any source of low
level forcing in terms of a front will likely hang up well northwest
of the Ohio Valley as parent upper forcing turns north near or west
of the Great Lakes. A fairly sharp west to east gradient in
precipitation coverage could occur as an upper ridge now looks to
build across the eastern U.S. by late week into the weekend. Areas
along the higher terrain of far eastern Kentucky would still likely
see isolated storms due to orographic lift, but larger scale
synoptic forcing could be minimal to nil. Will have to wait and see
if the upper low lifting near the Great Lakes can turn east and
bring any more widespread showers and storms into next weekend.
Temperatures will continue to ride above normal with highs
generally in the low 80s and lows in the low 60s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
ISSUED AT 822 PM EDT SUN MAY 22 2016

Convection continues to fire this evening across mainly our
eastern most counties. High res, short term models do not show
any definitive decrease in activity until after sunset. A few
thunderstorms have fired north of SJS within the last several
minutes and these cells are moving towards SJS. Consequently
updated the forecast to reflect VCTS for an hour or two.
Otherwise, convection is expected to die down after sunset. With
much drier air within the boundary layer, fog is not expected to
be as prevalent tonight as it was this morning. Thus fog should
develop late tonight mainly in the river valleys where there is a
better source of moisture. But fog is not expected to bring
reductions below VFR for any extended periods of time at our
forecast terminals. SME`s relative river valley locations makes it
most prone to any fog that does develop. Winds will be light but
generally out of the north-northeast through the period.

&&

.JKL Watches/Warnings/Advisories...None.

&&

$$

UPDATE...RAY
SHORT TERM...GREIF
LONG TERM...GUSEMAN
AVIATION...RAY


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