Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 190605 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
105 AM EST Sun Nov 19 2017

.UPDATE...
Issued at 1245 AM EST SUN NOV 19 2017

Will update the grids and forecast text products to drop the wind
advisory for the western tier of counties at 1 am as the winds
start to subside from west to east. The rest of the counties will
see their advisory run until 4 am and the main zone package
update. Did also fine tune the PoPs in the near term and add in
the latest obs/trends for the T and Td grids. These have been sent
to the NDFD and web servers. The updated ZFP, HWO, and NPW will
follow shortly.

UPDATE Issued at 1026 PM EST SAT NOV 18 2017

Issued an update to the forecast to input the latest observations
and trend them into the night time hours. The line ahead of the
front has weakened and evidence of lightning has disappeared and
so have remove thunder from the forecast. Also adjusted pops
according to the line progressing faster through the area
tonight. Will keep a small chance pops through the night behind
the front as some low level moisture will be slow to exit. With
the colder air rushing in later tonight, some of the higher
terrain to change over to snow. A new zfp has been issued with
this update.

UPDATE Issued at 615 PM EST SAT NOV 18 2017

Issued an update to the forecast to input the latest observations
and trend them into the evening. Also fine tuned the timing of
showers and thunderstorms into the area, The rest of the forecast
remains on track.

&&

.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 06Z TAFS through 06Z Sunday night)
ISSUED AT 105 AM EST SUN NOV 19 2017

The main concern for aviation will be gusty winds and some MVFR
to IFR cigs which will continue over the area through the rest of
the night. These cigs will last through tomorrow morning before
lifting around or just after 18Z as the last of the low level
moisture moves out of the area. Winds will remain gusty through
the night from the west at up to 35 knots, initially and then
diminishing with time. By morning the west to northwest winds will
be down to around 10 to 15 kts continuing fairly steady through
the day.

&&

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

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

&&

$$

UPDATE...GREIF
SHORT TERM...JMW
LONG TERM...SBH
AVIATION...GREIF



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