Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 201747
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1247 PM EST Fri Jan 20 2017

.UPDATE...
Issued at 949 AM EST FRI JAN 20 2017

Aside from a few sprinkles in some places, it appears the precip
is finished, and the POP has been reduced to below 20% for the
remainder of today. There are also some breaks in the clouds, and
the sky cover for today into tonight has been updated based on
latest obs and model forecasts. Otherwise, have only blended
mid-morning obs into the afternoon forecast.

UPDATE Issued at 745 AM EST FRI JAN 20 2017

Freshened up the grids to reflect the back edge of the rain
showers and lower PoPs through the rest of the day. Also touched
up the T and Td grids per the latest obs and trends. These have
been sent to the NDFD and web servers. A new set of zones were
issued, as well.

&&

.SHORT TERM...(Today through Saturday)
Issued at 350 AM EST FRI JAN 20 2017

08z sfc analysis shows a healthy area of low pressure moving
through the Mid Mississippi Valley. From this, a warm front is
lifting into eastern Kentucky with a band of moderate rain showers
pushing across the CWA ATTM. Most locations will measure from
this early this morning with an average of a quarter to half an
inch of rain common through dawn. Another very mild night is
underway for this time of year with readings not far from 50
degrees and dewpoints similar. Aside from in the band of heavier
showers, winds are generally light and from the south to southeast
across the area early this morning.

The models are in good agreement aloft through the bulk of the
short term portion of the forecast. They all depict a lead trough
pivoting through the Great Plains/Midwest and sending the core of
its energy through Kentucky early this morning. Heights will then
rebound over the CWA today as the next mid level low grinds into
the Central Plains. This will resume our bout of deep level
southwesterly flow along with ample bits of energy riding through
the region. The model spread with these key features does expand
late in the period, but the general pattern is pretty well set
continuing the southwest flow to 00z Sunday and beyond.
Accordingly, have favored a general model blend with a hedge
toward the latest HRRR in the near term.

Sensible weather will feature the bulk of the pcpn with this
latest wave passing through by dawn for most places - running out
ahead of the lifting warm front. In the wake of this, some
lingering showers will remain behind this morning and fade out by
afternoon as the trend favors drying through the rest of the day
but also continued warm conditions. For tonight, do anticipate a
ridge to valley temperature split opening up along with patchy
valley fog developing. The next wave of pcpn then moves into the
area from the southwest on Saturday afternoon with another
quarter to half inch of rainfall possible through evening - while
this unusual winter warmth continues unabated.

Again used the CONSShort and ShortBlend as the starting point for
most elements through the short term portion of the forecast. Did
make some terrain based adjustments for lows tonight given the
pattern favorable for an inversion and temp splits. Also,
adjusted PoPs to better time the passage of the bulk of the
showers this morning.

.LONG TERM...(Saturday night through Thursday)
Issued at 305 AM EST FRI JAN 20 2017

The primary focus in the extended will be a strong area of low
pressure that is forecast to move out of the southern Plains along
the southern stream of the jet stream Saturday night and Sunday.
This system is still expected to deepen as it cross the Tennessee
valley and moves into the Mid Atlantic region Sunday night and
Monday and eventually into New England Monday night and Tuesday.
With so much warm air in place, this system will produce nothing but
rain for our part of the country. The rain could be locally heavy at
times Sunday through Monday. We may see a few thunderstorms Saturday
night and Sunday, as a strong area of low pressure moves by just to
the south of the area. The rain will taper off from west to east on
Tuesday, and should be out of the area by the end of the day
Tuesday. The models are having trouble dealing with the evolution
and coverage of precipitation associated with a second weather
system that is progged to move across region Tuesday night through
Wednesday night. This the GFS and ECMWF are both moving an area of
low pressure quickly across the Great Lakes during the middle of the
week, with a cold front trailing from it that would extend southward
from the lower Great Lakes southward to the Gulf Coast. The issue
here is that the models are washing out the front as it moves
eastward, with very little QPF associated with it as it does so.
That being said, decided to keep Tuesday night and Wednesday dry, at
least until the models are able to converge on a common solution
that produces precipitation across eastern Kentucky. Did decide to
include some precipitation in the forecast for the area Thursday
through Friday, per the latest model blend and ECWMF solutions.
There is some uncertainty involved in that part of the forecast,
will go with only a slight chance of precipitation to finish out
next week. There could be enough cold air in place to allow for some
snow Thursday night, but not enough to cause any issues should it
actually occur.

Temperatures are still expected to be above normal to begin the
period, with daily highs in the 50s Monday through Wednesday, and
nightly lows in the generally in the 40s. The second half of the
week will be much cooler, as cooler air filters into the area behind
the departed area of low pressure that is expected to bring precip
to the area to start the week. Highs on Thursday and Friday are
expected to only make it into the 40s, with lows expected to fall
into the 30s on Thursday morning, and around 30s on Friday morning.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1247 PM EST FRI JAN 20 2017

A mix of VFR and MVFR conditions existed at TAF issuance, but
conditions were showing an overall improvement. Restrictions were
due to ceilings. From late afternoon on, VFR is expected to last
well into the night. Some locations are expecting ceilings to
again drop to MVFR for a time Saturday morning, but confidence is
not high in this scenario.

&&

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

$$

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



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