Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 140530
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1230 AM EST Tue Nov 14 2017

.UPDATE...
Issued at 1230 AM EST TUE NOV 14 2017

An area of surface high pressure is now centered across southern
Ohio tonight. The low level moisture remains trapped tonight
under strong inversion aloft and leaving the low stratus in place
tonight. Overall the forecast looks on track, but temperatures may
struggle to fall much further tonight given the clouds. Did make
some minor adjustments to temperatures and then blended in latest
obs.

UPDATE Issued at 1028 PM EST MON NOV 13 2017

Clouds continue to hold over the area with temperatures staying
around 40 thus far. Had to increase temperatures a bit more given
the slower than expected fall, but otherwise, forecast is on
track.

UPDATE Issued at 609 PM EST MON NOV 13 2017

GOES-16 Advanced Nighttime Microphysics RGB showing low clouds
entrenched over central and eastern Kentucky. With the sun now set
and low level flow veering to the northeast, pretty good bet the
clouds will persist through the night. In fact, NAM Bufr soundings
show this moisture trapped below a stout inversion into Tuesday
morning. With the increased cloud cover tonight, bumped up lows a
good 5 to 7 degrees to put them into the mid to upper 30s.
Finally, slowed down the temperature rise Tuesday morning with the
lingering cloud cover in place. It does look like we should see
more holes start to develop by midday Tuesday with the clouds
finally eroding through the afternoon.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 349 PM EST MON NOV 13 2017

A blanket of stratus remains locked in across eastern Kentucky this
afternoon as surface ridging builds into the Ohio Valley. Despite
drier northwest flow filtering in aloft, a hefty subsidence
inversion has kept abundant moisture trapped below 3000 feet. This
should further descend tonight, keeping low ceilings in the offing
for much of eastern Kentucky through the night. May see some
semblance of clearing in the Lake Cumberland region later tonight as
winds veer northeasterly, but the core of the ridge and northwest
winds extending back to near Chicago currently at mid-afternoon
hints at a prolonged period of cloudiness. Have therefore negated
much in the way of a ridge/valley temperature split in tonight`s
forecast lows given the lack of expected radiational cooling. As
opposed to fog, lowering cloud ceilings will pose more of a stratus
build down type scenario with ridges seeing a reduction in
visibilities.

Precipitation chances will remain nonexistent locally as a shortwave
trough skirts the Great Lakes late tonight into Tuesday morning.
High pressure shifting east across the Appalachians will further
veer winds and promote downsloping, aiding in finally mixing out the
thick blanket of low level cloud cover. The aforementioned
subsidence inversion will hold strong with moisture lingering in the
lowest few thousand feet off the deck, but it will be less
concentrated as mixing and more near surface sinking motion kick
in. Gradually clearing skies and warming aloft should help propel
temperatures back into the upper 40s to mid 50s through the
afternoon.

Clearing skies on the backside of the departing ridge should allow
temperatures to drop off fairly quickly Tuesday evening/early night,
before high clouds and potentially some in the mid levels approach
from the west later Tuesday night downstream of a wave diving from
lower Canada into the Midwest. This will likely equate to a
noticeable ridge/valley temperature split as ridges fall into the
mid 30s with valleys dropping off into the low-mid 30s.

.LONG TERM...(Wednesday through Monday)
Issued at 349 PM EST MON NOV 13 2017

The extended period will feature a couple of periods of rain, the
first Wednesday afternoon through late Thursday morning and the
second from late Friday afternoon through early Sunday morning. The
second episode of precipitation looks to be the more significant of
the two, with a longer period and probability of rain expected, and
higher rainfall amounts than the mid week event. In general,
temperatures during the period are expected to be below normal, with
the colder temperatures forecast to occur toward the end of the
period. Highs the first several days of the extended should be in
the 50s. At this time it appears that the exception will be Friday,
when we could see the mercury max out in the upper 50s and lower 60s
in a warm air advection pattern ahead of an approaching cold front.
A sharp cool down is then expected this weekend, as much cooler air
is forecast to spill into the area behind the departed front. In
fact, highs on Sunday may only reach the low to mid 40s. Nightly low
temperatures should be in the 30s and 40s. Sunday morning could see
the mercury fall into the mid 20s across the area.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 1221 AM EST TUE NOV 14 2017

An area of high pressure is now centered across southern Ohio
tonight and we are seeing light north and east flow across
eastern Kentucky. The consequence of low level moisture, surface
high and strong inversion aloft has been a persistent stratus
deck. The good news is some improvements have begun with a few
sites seeing low VFR tonight. However, the more eastern sites of
SJS/JKL have seen a mix of MVFR/IFR tonight. There will probably
be some fluctuations tonight between MVFR/IFR at SJS/JKL, but
think the other sites could remain mostly low VFR tonight based on
the latest trends. All sites will see improvements to VFR through
the day and probably clear to just a few high clouds late in the
day. Winds will remain light tonight out of the north and east.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...DJ
SHORT TERM...GUSEMAN
LONG TERM...AR
AVIATION...DJ



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