Area Forecast Discussion
Issued by NWS Jackson, KY-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS63 KJKL 220840
Area Forecast Discussion
National Weather Service Jackson KY
440 AM EDT SUN MAY 22 2016
-- Changed Discussion --(Today through Monday)
Issued at 425 AM EDT SUN MAY 22 2016
Early this morning, a trough extended from Eastern Canada south
into the Eastern Conus. A ridge extended from Mexico north into
the Plains and Upper MS Valley region, while a trough encompassed
much of the Western Conus. A shortwave moving through the Eastern
Conus trough is rotating away from the region at this time.
However, another couple of shortwaves are dropping south into the
Great Lakes region and Northeast Conus. Clouds have largely
cleared across the region and fog has formed in some valley
locations and some of the AWOS and ASOS sites around the region
have reported dense fog at times.
The main concern early this morning is the fog and dense fog
across the region. Since skies have cleared over the vast majority
of the area with the VA border counties being the exception and
generally light winds are being reported outside of the highest
terrain, the fog may become more widespread and dense toward dawn.
A dense fog advisory remains in effect for the southwest portion
of the CWA and trends will continue be monitored for any potential
expansion of this over the next few hours. What fog develops
should lift and dissipate through about 9 or 10 AM EDT or about 2
to 3 hours or so after sunrise. Otherwise, relatively cold air
aloft and the shortwaves rotating down through the trough and
generally passing to our east should combine with daytime heating
for steepening lapse rates and a rather extensive CU field by this
mid afternoon across the central and eastern portions of the CWA.
Some showers should also develop and a thunderstorm or two cannot
be ruled out.
Rising heights are expected overnight tonight as the southern
portion of the trough closes off to a closed low that meanders
toward Eastern VA and the axis of the mid level ridge nears. At
the same time, sfc high pressure will also build into the area.
This should set the stage from clearing skies tonight along with
slackening winds. Temperatures especially in valley locations
should reach or fall below afternoon crossover temperatures
anticipated to be in the mid to upper 40s and fog should develop
again tonight. With some solar insolation today and drier air
advecting in, confidence in the areal extent of the fog and
whether or not it might become dense is not all that high.
However, what dense fog that does develop will probably be across
the eastern or southeaster valley locations.
Daytime heating under the influence of the ridge should produce a
CU field on Monday afternoon, especially across eastern sections
of the area as the Slow moving upper low meandering toward the Mid
Atlantic coast should bring or keep the atmosphere relatively
moist near 850 mb. The airmass will moderate a bit as well with
mid 70s in most areas.
.LONG TERM...(Monday night through Saturday)
Issued at 420 AM EDT SUN MAY 22 2016
A strong upper level closed low, along with surface low pressure,
will be positioned just off the coast of the eastern Carolina`s as
of 0z Tuesday, and should continue to ride up the Atlantic seaboard
Monday night through Tuesday. As it slowly moves away, heights will
begin increasing across the Commonwealth as steep upper level
ridging moves in. At the surface, broad high pressure will take
hold, allowing for mostly clear conditions, light and variable
winds, and temperatures rising to near 80 degrees.
By Tuesday night, a shortwave will move through the upper level
ridging pattern. This, in addition to southerly winds tapping into
warm...moist...unstable Gulf Coast air, will provide the ingredients
necessary to invoke convective activity across the region beginning
Wednesday and continuing through Wednesday night. Best instability
for thunderstorm development will be during the afternoon and into
the evening, before a surface inversion and decreasing lapse rates
effectively cut off thunder potential between 3 and 6z Thursday.
Several more shortwaves are expected to traverse KY for the latter
half of the workweek. Continued southerly flow and warm/moist
advection will keep precip chances in the forecast from Thursday
through the weekend, with afternoon heating leading to thunderstorm
concerns, followed by quick decreases in instability overnight.
Unfortunately, model solutions lose considerable agreement between
Friday and Saturday, so stuck with a model blend for pops from this
point on, which generally keeps chance pops to round out the
extended portion of the forecast. Each day during the extended
should expect similar temperatures in the upper 70s and low 80s.
-- End Changed Discussion --
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
ISSUED AT 220 AM EDT SUN MAY 22 2016
The clearing form the west and northwest has led to improvement in
CIGS to VFR as far southeast as JKL and SJS. However, dense fog
has developed or been reported at least at times at SME and SYM
with some indefinite ceilings. As clearing continues to move into
to the remainder of the area, additional areas of dense fog should
develop. At this time, dense fog is expected to also affect LOZ,
JKL, and SYM at least briefly by 11Z. For now, we expect that
drier air moving into the northwest should lead to improvement or
at least limit dense fog at SYM. Improvement to VFR should occur
in all locations 12z to 14z, however, daytime heating should
steepened lapse rates and lead to redevelopment of a substantial
CU field by 17Z along with the threat of some instability
showers at SYM, SJS, and JKL. Winds will be generally be out of
the west-northwest through the forecast period, averaging 10 kt
Dense Fog Advisory until 9 AM EDT this morning for KYZ068-069-