Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 240824
AFDJKL

Area Forecast Discussion
National Weather Service Jackson KY
424 AM EDT WED AUG 24 2016

.SHORT TERM...(Today through Thursday)
Issued at 352 AM EDT WED AUG 24 2016

Moisture continues to increase across the region this morning with
west to southwest flow in place at the surface up to mid/upper
levels. This has allowed mid and high level clouds to increase in
coverage and dew points to rise towards the mid 60s. Luckily, this
increase in cloud cover has kept most fog development at bay early
this morning. While shower activity should be sparse today, there
may be just enough moisture and lift to spark off a few showers
this afternoon. This shouldn`t be a big deal as widespread mid and
upper level forcing is absent during the day.

On Thursday, a cold front extending from a surface low along the
United States/Canadian border, will shift towards the Ohio Valley.
The front will attempt to cross into Kentucky but is expected to
weaken and fall apart as it runs into a dominate upper ridge in
place over the southeastern CONUS. In fact, the upper ridge is
expected to reinforce itself over Kentucky Thursday afternoon,
limiting any shower activity to the northern and eastern counties
during the morning hours. Skies will begin to clear Thursday
afternoon/evening as surface high pressure builds back into the
Ohio Valley.

Temperatures will warm into the upper 80s today and tomorrow,
with some locations hitting that 90 degree mark on Thursday.
Humidity will also be higher, making for more muggy and
uncomfortable conditions through the short term.

.LONG TERM...(Thursday night through Tuesday)
Issued at 420 AM EDT WED AUG 24 2016

The long term period is expected to begin with an upper level ridge
of high pressure centered over the Southeastern States while a
weakening upper level low and associated shortwave trough is
expected to be nearing the Western Great Lakes. At the surface an
area of low pressure will be moving from Ontario into Quebec, with a
cold front trailing south and southwest into the Great Lakes, Mid MS
Valley and on into the Plains. A ridge of high pressure should
extend from the Southeastern States to off the Northeast US Coast
with the boundary separating this high from another sfc high
centered over the Plaisn and Rockies.

From Thursday night into Friday, the upper low is weaken to an open
wave and approach the Canadian Maritimes by Friday evening.
Meanwhile the associated surface low will also move east from
Ontario and toward the Maritimes during the period. However, the mid
and upper level ridging across the Southeast is expected to build
north and east and be centered near the Blue Ridge Region of VA and
NC by the end of the period. The shortwave weakening and shearing to
the north and east and the ridging over the Southeast will lead to
the cold front becoming increasingly sheared likely more diffuse as
well with time as it drops south of the Ohio River on Friday. It
should usher in a very minimally drier airmass for the start of the
weekend. With the approach of the cold front and a moist airmass in
place, cumulus should develop during peak heating along with a few
showers and thunderstorms.  Even with the front progged to move
across the area on Friday, lack of mid level forcing and the
proximity of the center of the upper level ridge and some height
rises, coverage should be isolated. Upper 80s to lower 90s are
expected for highs outside of the high terrain on Friday. Dewpoints
mainly in the lower 70s should yield heat indices well into the 90s
and a couple of spots might touch a heat index of 100 briefly.

Surface and upper level ridging should remain dominant over the
weekend and into the first half of next week. During this time, an
upper level low or shortwave trough should move from the Plains to
the Great Lakes and then across Southern Canada and the Northeast US
toward the end of the period. This pattern should also send a
boundary south and east across the Great Lakes and into the
Northeast US. However, as this boundary nears the OH River the
persistent ridging should slow it down or stall it out north of the
area. There does remains some model variability as to how close the
center of the ridge will be to Eastern KY over the weekend along
with variability in the magnitude of 500 mb heights with it and
timing differences with the trough passing by to our north and west
over the weekend into early next week. Of note, but of no affect to
Eastern KY through the end of the Long Term period is a possible
tropical system moving into the Gulf of Mexico by Monday or Tuesday
as it works around the Southern Periphery of the Southeastern/
Southern US ridging.

Nevertheless, this pattern should keep the summer time heat and
humidity in place over the weekend and through the end of the
period. The airmass should be moist enough for at least diurnally
driven cumulus each day, with some of this possibly able to break
the cap in a few locations. This would appear most probable over or
near the higher terrain near the VA border over the weekend, and
then as the ridge weakens and becomes centered further from the
area, possible across more of the area from Monday into Tuesday.
Slightly better chances for convection will be across the north on
Tuesday closer to an approaching boundary. High temperatures
averaging in the upper 80s to lower 90s for highs with overnight
lows around 70 are expected over the weekend and into the start of
next week. Heat indices should reach the 90s each day and possibly
near 100 in a few locations.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 140 AM EDT WED AUG 24 2016

With surface high pressure now off to our east, moisture has begun
returning to East Kentucky. This is evident with the increase in
mid to high level clouds early this morning. However, no aviation
impacts are anticipated through the period other than some patchy
fog potential in the deepest valleys and near bodies of water.
Winds will be light and variable through the period.

&&

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

$$

SHORT TERM...JVM
LONG TERM...JP
AVIATION...JVM


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