Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 200610 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
110 AM EST Fri Jan 20 2017

.UPDATE...
Issued at 1245 AM EST FRI JAN 20 2017

The gridded forecast is on track so have just nudged it toward the
latest obs and near term trends. These have been sent to the NDFD
and web servers.

UPDATE Issued at 1125 PM EST THU JAN 19 2017

WSR-88D continues to display rains showers spreading north and
east this hour, but downsloping is playing a role in eating some
of this activity based on latest surface analysis. Do still
suspect most will see some measurable precip before all is said
and done the amounts will just be lower in the SE. Overall this
has already been forecast in the grids and only changes needed
were to deal with latest obs and radar trends.

UPDATE Issued at 1000 PM EST THU JAN 19 2017

WSR-88D continues to show rain showers spreading slowly north and
east this hour. Most of the amounts have been light across the
CWA, but areas toward the Lake Cumberland region have pick up
around a quarter of an inch. Rain showers will continue to spread
east through the night and adjusted POPs with latest trends. Also
adjusted for latest obs and trends.

UPDATE Issued at 837 PM EST THU JAN 19 2017

WSR-88D radar showing best coverage of rain showers remains
across the Lake Cumberland region this hour. It seems like some
downslope flow is keeping precip more confined to those areas
initially. Either way think the moisture will continue to spread
east through the night leading to rain for most overnight. Did
speed up the overall progression east, as some of the short term
guidance was too slow including the HRRR. The models are also
struggling with a induced 850mb jet that punches north through the
night, and right now would think the short term guidance has best
handle over the faster GFS solution. The previous assessment of
the jet was based on 00Z soundings and current VAD wind profiles.
Overall the jet alignment would bring better QPE to areas along
and west of the I-75 corridor and more also over the Bluegrass.
Also updated with latest obs and trends in terms of
temps/dews/winds.

UPDATE Issued at 540 PM EST THU JAN 19 2017

WSR-88D radar showing initial band of precip moving toward the
Bluegrass and this is lining up close where the warm front is
most likely located. The overall better upper level dynamics and
rainfall will progress north and east through the night. The
challenge this shift will be how much do we speed this up based on
the latest surface/remote sensing trends versus the latest
guidance trends. That said much of the guidance remains on the
slow side at this point including the HRRR. Did opt to speed
things up some this update based on the radar trends and will
continue to assess this for the next update. Otherwise this update
included freshening up the latest obs and overall trends for
temps/dews/winds.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 415 PM EST THU JAN 19 2017

A small area of showers has moved into the southern part of the
JKL forecast area this afternoon. This is teaser in front of a
large area of rain/showers over central and western KY at mid
afternoon. The precip was the result of an upper level wave
coupled with warm air advection. Models agree on this precip
moving through the region tonight. Downslope flow will cut into
the precip in our eastern counties, but even there it should
eventually rain. However, precip totals will be lighter in the
east. Most of the precip will be exiting to the northeast with the
warm front around dawn on Friday, with just some spotty very
light showers possibly lingering into the day due to persistent
low level moisture. A few peaks at the sun in the warm air mass
will push readings into the 60s during the day. Mild, benign
weather is in store Friday night. Cloud cover on Friday night is
somewhat uncertain. MOS data and blended model data suggest quite
a bit of cloud cover. However, forecast soundings look like the
clouds could break. Have played it toward the MOS and blended data
for the time being.

.LONG TERM...(Saturday through Thursday)
Issued at 355 PM EST THU JAN 19 2017

The extended forecast period begins on Saturday with a continued
active and somewhat progressive pattern through the weekend and
into next week. The first feature of the extended will eject northeast
from the lower MS valley and into the southern Appalachians
bringing light rainfall into eastern Kentucky. As the next feature
continues to lift north through the area, some decent instability
will advect into the area Saturday afternoon through Sunday
afternoon. In fact, models and SPC show at least a slight chance
for general thunder in the area. Will stay with collaboration with
neighboring forecasters and SPC and keep thunder in the forecast
through the weekend. In addition, the unseasonal airmass advecting
into the area will allow for temperatures soaring into the upper
60s for highs across eastern Kentucky, possibly breaking a few
records on Saturday and while not as quite as warm on Sunday,
still a good 20 to 23 degrees above normal.

Heading into Monday, another upper low dives into the lower MS valley
before ejecting east and up along the lee side of the Appalachian
Mountains bringing additional rain into eastern Kentucky.
Expecting an additional half an inch with this rainfall to impact
the far eastern Kentucky areas. As this feature exits, colder air
filtering in behind may allow for rain to change to a mix of rain
and snow on top of Black mountain on Monday night. After a break
in the weather on Tuesday, another bout of southerly flow will
allow high temps on Tuesday and Wednesday will climb near 60
degrees again before another bout of rainfall moves into the area
late Wednesday afternoon through Wednesday night.

As the front passes through late Wednesday night, this will begin an
overall cooling trend through Wednesday night and beyond Day 7.

In summary, much of the extended remains warm and wet with the
consensus being around a couple inches of rain through eastern
Kentucky but the GFS is quite a bit wetter than the Euro on the
Sunday night into Monday system. The consensus is a bit less but
something to keep in mind heading into next week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 110 AM EST FRI JAN 20 2017

The initial VFR CIGs will start to degrade through the heart of
the night as the next surge of showers moves into the area from
southwest to northeast. This will bring MVFR cigs and vis to the
TAF sites with occasional IFR conditions possible through mid
morning Friday. The showers will scatter out by midday with
improving aviation conditions to follow into Friday evening. For
the most part, we are looking at light winds for the period with
direction from SE initially and then veering around to the SW
during the day, Friday.

&&

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

$$

UPDATE...GREIF
SHORT TERM...HAL
LONG TERM...HAL/SHALLENBERGER
AVIATION...DJ/GREIF


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