Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 240227
AFDJKL

Area Forecast Discussion
National Weather Service Jackson KY
1027 PM EDT TUE AUG 23 2016

.UPDATE...
Issued at 1027 PM EDT TUE AUG 23 2016

Only a few tweaks needed for this update. The temps have been
tricky in some of the eastern valleys as expected, and therefore
updated temps and min temp grids to reflect the latest trends.
Also tried to update the sky grids with the latest SAT data.
otherwise overall forecast grids are on track.

UPDATE Issued at 555 PM EDT TUE AUG 23 2016

Surface high has moved east and we are starting to see a bit more
moisture stream northeast. Therefore we are seeing a increase in
mid to high level clouds this afternoon. The temps could be a bit
tricky in some of the more prone valley sites (depending on
clouds) but will have minimal impact. Little if any changes needed
with this update but did a quick freshening up of temps/dews/winds
with latest obs.

&&

.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...(Thursday through Tuesday)
Issued at 349 PM EDT TUE AUG 23 2016

High pressure which has encompassed the Ohio River Valley during the
short term will have pushed east and along the Atlantic coast by 12Z
Thursday. Return flow will continue to pull warm southerly air into
the region during the day Thursday, boosting daytime temps to near
90 degrees once more, with decent humidity values. Meanwhile, broad
upper level ridging will remain in control across much of the
southeast conus. A closed low which will traverse the central
Canada/US border through the short term will begin to lose strength
as it nears the Great Lakes region Thursday, foregoing forward
propagation with the stationary high ridge in place. A surface low
pressure system will follow along, with a cold front expanding
southeast across the the central plains. However, with the weakening
low and loss of forward motion, the cold front will start to sheer
out and lose strength before ever reaching the Ohio River Valley.

So what does this mean for eastern KY? With our location between the
slowly approaching cold front, and the return flow of the exiting
high pressure system, the stage will be set for possible convection.
However, with upper level ridging still in predominate control, all
forcing will be limited to the low levels with little upper level
dynamics. Both the GFS and ECMWF bring some isolated pops into the
region Thursday. However, the location and timing of this is still
somewhat very uncertain, and will likely be limited to peak diurnal
heating to produce enough lift. The frontal zone finally progresses
southeast through the state late Thursday night and into the day
Friday. But even then it will be very weak, and the lack of forcing,
in addition to two strong high pressure centers on either side of
the frontal boundary, will keep pops isolated, with only light QPF
expected. In fact, we may not even see much in the way of cloud
cover as it passes over, and any convection that does develop
will be dependent on afternoon diurnal development.

High pressure should take hold post frontal Saturday and Sunday.
However, another shortwave will move across the north central conus
through the weekend, which may pull enough moisture from the south
to impact portions of KY for the latter half of the weekend and into
the first part of the week. Unfortunately the models are not in good
agreement on this feature, or the depth of moisture. So once again,
will stick with the blend of models for pops during this point to
account for all the model differences. This kept isolated pops
across portions of the CWA Saturday afternoon, and isolated to
scattered chances again Sunday afternoon and Monday afternoon.

Temperatures will modify little during the extended period,
despite the frontal passage, with no strong wind shifts in place.
Expect upper 80s to around 90 degrees and decent humidity each day
through the weekend.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 725 PM EDT TUE AUG 23 2016

Surface high pressure has moved east into the Mid Atlantic region,
and Consequently we will begin to get back into the return
moisture side of the high. Right now this will only lead to a
increase in mid to high clouds in terms of aviation. Also light
winds will remain the story for the TAF period.

&&

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

$$

UPDATE...DJ
SHORT TERM...KAS
LONG TERM...JMW
AVIATION...DJ



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