Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 182100
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
400 PM EST Sat Nov 18 2017

.SHORT TERM...(This evening through Sunday night)
Issued at 400 PM EST SAT NOV 18 2017

Gusty southerly flow continues this afternoon ahead of an
approaching cold front. This cold front is poised to traverse the
CWA between 22Z and 3Z, bringing with it a line of showers and
thunderstorms. This line is fairly thin over western KY at the
moment, though all the latest CAM models continue to be in good
agreement that the line with lose strength and spread out as it
moves towards eastern Kentucky. A few lingering storms are
possible, but should be dissipating. That being said, any storms
or heavy showers will have the potential to mix down gusts near 60
mph (severe potential) through the evening. Removed mention of
thunder in the grids after 3Z. Otherwise, still expecting gusts
between 35 and 50mph through the remainder of the afternoon and
into the evening in the prefrontal environment. Once the front
passes over, winds will become more westerly and lose magnitude,
though will likely remain breezy throughout the remainder of the
overnight and during the day Sunday.

Westerly flow will also pull in much drier air. Precip is
expected to taper off behind the front, especially after 6Z,
however some showers and sprinkles could linger in the far east
under this flow regime through Sunday morning. The influx of cold
air could still cause some snow to mix in with the rain as it
tapers off. The only place that this should have any impact will
be the highest peaks, generally above 2,500 feet, where a few
tenths of an inch of accumulation are expected. Actually lowered
snow and QPF amounts from previous forecast since the trend has
been to move precip/QPF out of the CWA faster.

As we head into the day Sunday, a steep llvl inversion could keep
some moisture trapped and lead to continued cloud cover throughout
the day. This will interact with the cooler flow into the region,
keeping temperatures from reaching 40 degrees in many locations
Sunday afternoon. Breezy and cool will be the story for the day.
Models show the clouds clearing out into the overnight Sunday
night, however based on recent events, wouldn`t be surprised if
they stuck around a bit longer. This could tamper with overnight
lows. As it is now, if the clouds do clear in the first part of
the overnight, as the models predict, temperatures could easily
drop off into the mid 20s. Winds will lighten substantially and
back to a more SW direction late in the night. This could lead to
significant decoupling, with sheltered valleys dropping into the
low 20s. Wouldn`t be surprised if this is even lower in some
locations, but given the uncertainty about the clouds, did not go
to aggressively. Definitely something to keep an eye on in the
upcoming forecasts.

.LONG TERM...(Monday through Saturday)
Issued at 250 PM EST SAT NOV 18 2017

There is good model agreement with the evolution of the overall
mean upper air pattern, but there are considerable differences in
the details. This is not surprising considering we will be in a
fairly progressive pattern through the coming week. The progressive
pattern will result in a roller coaster pattern for temperatures
from Monday through Saturday. Moisture will remain limited, with
the next chance for rain not coming until next Saturday.

The week will begin on a cold note, with an upper level trough axis
to our east, weak upper ridging over the MS valley, and surface high
pressure over the central and southern Appalachians. As the surface
high shifts east from Monday into Tuesday and weak upper ridging
builds over the area in advance of the next upper trough, we`ll see
a quick warm up into Tuesday. That will be short lived as the next
trough moves east and drives another cold front across the area
Tuesday night. There will be very limited moisture with this front,
and no precipitation is expected, but it will bring colder
temperatures back to the area for Wednesday and Thanksgiving Day.
Another warm up begins late in the week that will last into next
weekend. Rain chances will return next Saturday as yet another cold
front approaches the area. Looking just beyond the forecast period,
indications are for another shot of cold air late next weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 100 PM EST SAT NOV 18 2017

A cold front continues to approach the region, resulting in strong
and gusty southerly flow. sustained winds between 10 and 20 knots
with gusts between 35 and 50 mph will be possible at all TAF
sites this afternoon and evening. Isolated showers are also
starting to pop up across eastern Kentucky, but should pose little
concern with continued VFR VIS and CIGS. CIGS are expected to
continue lowering to MVFR as the cold front nears the region late
this afternoon/evening. Along the actual front, more widespread
showers (and possibly an isolated thunderstorm) will occur which
may lower VIS to MVFR (or possibly lower at times), passing from
west to east generally between 21Z and 3Z. However light rain
could linger through 6Z. Rain will continue to taper off through
the rest of the overnight as winds become more westerly and
entrain in drier air. Wind speeds will also quickly decrease
behind the frontal passage. Dry but MVFR CIGS are expected to
continue into the day Sunday.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 1 AM EST Sunday for KYZ044-050>052-058>060-
068-069-079-080-083-084-104-106-108-111-114.

Wind Advisory until 4 AM EST Sunday for KYZ085>088-107-109-110-
112-113-115>120.

&&

$$

SHORT TERM...JMW
LONG TERM...SBH
AVIATION...JMW



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