Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 231848

Area Forecast Discussion
National Weather Service Jackson KY
248 PM EDT TUE AUG 23 2016

.SHORT TERM...(This evening through Wednesday night)
Issued at 248 PM EDT TUE AUG 23 2016

Strong surface ridge remains to our east this afternoon with
moisture surging back northward across the lower and mid
Mississippi river valley on the western flank of this high. As the
high continues to slowly shift eastward tonight and especially
Wednesday, this moisture will eventually pivot back into eastern
Kentucky with the humidity on the increase. A band of mid level
clouds will work east early Wednesday morning. While activity
should be sparse with this moisture, there could be just enough
lift to spark off a few sprinkles. As the day wears on...low level
moisture should start to increase and this could aid in a shower
or two along the high terrain of Tennessee and Virginia and could
sneak just far enough north for a shower to develop in southern
Kentucky. This shouldn`t be a big deal as widespread forcing is
absent during the day.

Tomorrow night is a bit more uncertain as it looks like we may
have to watch how things unfold upstream as we could see
convection morph into a MCS and drop east and south into the area
overnight. Right now, opted to keep pops low with such uncertainty
on where convection will develop and ultimately track...but it
does appear the best chances to see some rain would be along or
north of I-64.

Temperatures will turn a bit milder tonight through Wednesday
night as dewpoints creep upward, and a more humid airmass takes
over. Lows tonight will remain in the 60s, with readings around 70
by tomorrow night. Highs on Wednesday will climb into the mid 80s,
despite the increase in cloud cover.

.LONG TERM...(Wednesday night through Monday)
Issued at 349 AM EDT TUE AUG 23 2016

The long term period is expected to begin with an upper level ridge
of high pressure centered over the Southeastern States while a
somewhat broad trough is expected to extend south through portions
of the Rockies and Plains States from an upper low moving east near
the US/Canadian border centered over southern Manitoba. Surface high
pressure that has brought a reprieve from the humidity is expected be
departing the Northeast at that point. Return flow between this high
and a cold front advancing toward the Great Lakes and MS Valley
ushering deeper moisture back into the Commonwealth. PW is projected
to have increased into at least the 1.5 to 1.75 inch range by the
start of the period. In addition, a few disturbances should
also be moving around the ridge at that point.

From Wednesday night into Friday, the upper low is expected to move
into and across Ontario and Quebec and 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 ridging across the
Southeast is expected to build north and east and be centered over
the Central or Southern Appalachians by Friday evening. This will
lead to the cold front becoming increasingly sheared with time and
probably more diffuse as well as it drops south of the Ohio
River. It should usher in a minimally drier airmass for the start
of the weekend. During the period of increasing moisture from
Wednesday night into Friday followed by the approach of the cold
front convection will be possible. However, mid and upper level
forcing should be minimal if not lacking much of the time. Thus
only isolated to scattered pops continue to be forecast during the
Wednesday night to Thursday period. Although nocturnal convection
will be possible on Wednesday night as a weak disturbance passes,
loss of daytime heating should lead to a dry or mostly dry period
on Thursday night. Even with the front progged to move across the
area on Friday the proximity of the center of the upper level
ridge and or height rises should keep coverage mainly isolated.
Upper 80s should be common for highs during this period with some
of the warmer spots or more southern valley locations reaching or
exceeding 90. Overnight lows will return to the upper 60s to lower

Surface and upper level ridging should remain dominant over the
weekend and into the start of next week. There remains uncertainty
as to how close the center of the ridge will be to Eastern KY during
this period. The past couple of ECMWF runs have higher heights from
Friday evening into Saturday night, while the GFS and the previous
ECMWF run have higher heights at the end of the period compared to
the 0Z ECMWF run. 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 each day. This would appear
most likely over or near the higher terrain near the VA border to
start the period. Then as the ridge possibly weakens or becomes
centered further from the area, the cap possibly could be broken
across more of the area on Monday. A warm and moist airmass will
be across the region in any case with dewpoints expected to be in
the upper 60s to lower 70s and 850 mb temps around 19C to 20C
should keep temperatures in the upper 80s to around 90 for highs
with overnight lows in the upper 60s to around 70 degree range.
Heat indices should reach the 90s each day in many locations.


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

VFR conditions will continue through the TAF forecast period. Some
mid level cloud cover will be seen late tonight into early
Wednesday, but only a few sprinkles are possible during this time.
Winds will remain fairly light.


.JKL Watches/Warnings/Advisories...


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