Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 212030
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
330 PM EST Sat Jan 21 2017

.UPDATE...
Issued at 1255 PM EST SAT JAN 21 2017

Mid/high level clouds have been rather thick today, and have
slowed the temperature rise. This is especially the case in
valleys which chilled very effectively before dawn, before the
clouds arrived. Thick that most valleys will eventually catch up,
but the hourly trends needed to be adjusted to account for it.
Some very light rain has been reported by the KLOZ ASOS, and have
left 20% pops in the forecast in the southeast part of the area
this afternoon. Radar is also showing returns near the northwest
edge of the forecast area. Have added a 20% pop there for this
afternoon, but it`s uncertain if precip can make it through the
drier air beneath where it`s originating.

UPDATE Issued at 940 AM EST SAT JAN 21 2017

The update only blends mid morning obs into the forecast grids,
with no substantive changes.

UPDATE Issued at 643 AM EST SAT JAN 21 2017

Forecast still on track early this morning. Middle and high level
cloud cover will continue to stream over the area today as a
weather system approaches from the southwest. Ingested the latest
obs into the hourly grids to establish new trends. No major update
to the forecast is required at this time.

&&

.SHORT TERM...(Today through Sunday)
Issued at 302 AM EST SAT JAN 21 2017

The models are suggesting that most of eastern Kentucky should
experience dry weather today, due to progressively southeasterly
flow and the downslope warming and drying that will occur across
the area as a result. It appears that the best moisture associated
with an approaching weather system will remain just off to the
south of our area today. This, combined with the downslope
warming and therefore drying mentioned above, should be enough to
keep precipitation at bay for all but our southernmost and
easternmost counties today. After a brief lull, widespread
rainfall is expected to move in from the south and southwest this
evening through the end of the day on Sunday. An area of low
pressure is forecast to move out of the southern Mississippi
valley and across the Ohio and Tennessee valleys tonight and
tomorrow. As this system moves east, it is forecast to strengthen,
and therefore slow down, as it moves across our area. The slow
movement of this system, combined with a steady flow of warm moist
air off the Gulf of Mexico, will lead to widespread rain showers
across eastern Kentucky to finish out the weekend. We may even see
a few thunderstorms tonight and tomorrow due to the strength of
the passing low and the presence of weak elevated instability.
Rain could be locally heavy at times.

Temperatures will remain well above normal this weekend, with
highs expected to top out in the mid to upper 60s today, and the
lower 60s on Sunday. Overnight lows should be in the lower 50s.
Mostly cloudy to cloudy skies will be on tap as well. Winds should
generally be out of the south or southeast at around 5 mph during
the period

.LONG TERM...(Monday through Saturday)
Issued at 330 PM EST SAT JAN 21 2017

The extended forecast period begins on Monday with a deep closed
upper low tracking northeast through the spine of the Appalachians.
As this feature tracks northeast, blocking over the New England and
Canadian Maritime region will hinder the exit of the back edge
precip moving through eastern Kentucky. This slow exit followed with
the approach of the colder air in behind on Monday night into
Tuesday may lead to a brief mix of rain and snow on top of Black
Mountain. In addition to this, models have been coming into more
agreement of a prolonged heavy rainfall event coming to an end
Monday evening into Monday night across eastern Kentucky. Some
lingering minor flood problems may be possible, if not just some
rivers running full. Both the Euro and GFS seem to have come to an
agreement on this with the Euro being slightly wetter. Will keep
this mention in the HWO.

Heading into the midweek time frame, a brief period of ridging moves
into the OH valley with a period of drying as southwest flow
increases ahead of the next incoming cold front. High temps on
Wednesday will climb into the upper 50s to low 60s with SW 10 to 20
knot winds bringing in an unseasonably warm airmass. In fact,
models are suggesting an overall drying trend to the approaching
front with the bulk of the moisture to the north over the Midwest
and into Ohio. Little if any precip is expected with this feature.


Passage of the front on Wednesday night will bring in a colder
airmass to the region by Thursday with a possible prolonged upslope
event taking shape for Thursday and Friday. At this point the
pattern brings in a longwave trough across the eastern CONUS into
the weekend. The northwest flow then brings a series of disturbances
in an upslope scenario. At this point, while the models hint at
temps being warm enough for rainfall during the day and snow showers
overnight, an upslope event with the correct wind component would
mean some convection and snowfall at warmer temps. For now, went
with a general snowfall at 34 degrees and below due to the
uncertainties in the models but this may need reevaluated. The
general trend is cooler towards the end of the extended but models
have backed off from the depth of the cold air. Due to this, will
leave any mention of snow out of the HWO as none is expected to be
impactful at this point.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 1255 PM EST SAT JAN 21 2017

VFR conditions are expected to prevail until late tonight, with
mainly mid/high level ceilings. A bit of light rain will affect
far southeast KY this afternoon, and possibly near/north of I-64,
but it should not offer up much in the way of restrictions. The
next round of more significant weather will not arrive until late
tonight. Showers and lower ceilings are expected to spread into
the JKL forecast area from the southwest before dawn on Sunday.
The worst conditions should be in the far west and southwest, with
at least MVFR if not IFR occurring on Sunday morning. Further
east, drying downslope flow will work to erode the lowest clouds,
and the eastern tip of the state should remain VFR. However, there
still could be some showers even in the far east before the end
of the period. A few thunderstorms can`t be ruled out in the
southern part of the area by mid day on Sunday.

&&

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

$$

UPDATE...HAL
SHORT TERM...AR
LONG TERM...SHALLENBERGER
AVIATION...HAL



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