Area Forecast Discussion
Issued by NWS Jackson, KY

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344
FXUS63 KJKL 141252
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
752 AM EST Sat Jan 14 2017

.UPDATE...
Issued at 752 AM EST SAT JAN 14 2017

This update realigns POP & weather grids this morning to account
for radar trends in the northern part of the area. Overall, the
forecast is on track and very few changes were made.

&&

.SHORT TERM...(Today through Sunday)
Issued at 430 AM EST SAT JAN 14 2017

A frontal boundary was stalled in the southeast CONUS early this
morning. A north/south temperature gradient was present over the
JKL forecast area. Overrunning moisture was leading to extensive
clouds, fog, and areas of precip north of the frontal boundary.
The general scenario is expected to hold through the period. Weak
impulses will determine when/where precip is more concentrated.
The GFS and NAM, and ECMWF all show general agreement on precip,
and see no reason to stray from a model blend to handle it. That
being said, aside from the showers skimming our northern counties
this morning, there will be two upticks in precip. The most
significant one will be this afternoon and early evening, and the
second and more minor one will be Sunday afternoon.

A dense fog advisory was discussed with neighboring offices. While
the fog has been dense in a few place, it`s mainly been on the
taller ridges. Elsewhere, reported visibility has mostly been
greater than 1/2 mile. That being the case, have held off on an
advisory. However, the situation will continue to be monitored,
and an advisory may be necessary if dense fog becomes more
widespread.

.LONG TERM...(Sunday night through Friday)
Issued at 430 AM EST SAT JAN 14 2017

The period will begin with baroclinic zone remaining somewhere
near the region, and this will lift north as more of a warm front
by Monday. Overall keep better POPs across the north Sunday night
and slowly wane POPs through Monday. There will be a general lull
in the precip on Monday before low pressure system across the
Southern Plains ejects into the Western Great Lakes by the time we
get to Monday night. There will probably be some showers develop
ahead of the attendant cold front late Monday night into Tuesday.
This is where the guidance begins to diverge in the upper level
synoptic pattern leading to surface feature inconsistencies. That
said, the 00Z GFS operational run phases the southern stream
trough and consequently deepening the northern stream trough
Monday night into Tuesday night. This northern stream trough then
negatively tilts leading to faster more progressive frontal
passage. Meanwhile the ECMWF/Canadian are slower as they dig a
northern stream spoke of energy across the Midwest and develop
another low along the said frontal boundary. This slower solution
would lead to longer resonance period of moisture streaming across
the region.

Thus the slower solution would lead to additional precip in the east
going into early Wednesday. WPC would suggest this will be a open
wave and not sure this will pan out given the more amplified
solutions offered by most of the model suites including their
ensembles. Overall too soon to call either solution, but we could
see some localized flooding issues especially considering the
antecedent wet conditions. Also there is some indication of seeing
convection which would further support localized flooding issues.
This system will pull east by Wednesday afternoon and evening time
frame with either solution offered. Therefore Thursday looks to be
dry at this stage of the forecast process. There is then another
Baja upper level low that ejects into the Southern Plains by
Thursday night and not surprising the models also diverge here too.
Right now will keep close to the blend given the varying synoptic
solutions, and this would support better POPs in the Lake Cumberland
region.

Temperatures through the period will remain above normal and at
times well above normal. Overall period offers one cooler day by
Wednesday in the wake of the front, however temperature remain 10 to
15 degrees above normal for afternoon highs. Some of these days will
also flirt with record high temperatures for this time of year.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
ISSUED AT 714 AM EST SAT JAN 14 2017

Initial conditions were IFR or worse area wide, with both
ceiling and visibility being problems. While some improvement in
visibility is expected for the afternoon, ceilings should remain
low, and conditions are not forecast to improve beyond IFR
any time in the period. In addition, light rain is expected for
much of the area this afternoon.

&&

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

$$

UPDATE...HAL
SHORT TERM...HAL
LONG TERM...DJ
AVIATION...HAL



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