Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 131650 AAA

National Weather Service Jackson KY
1150 AM EST Tue Nov 13 2018

Issued at 1149 AM EST TUE NOV 13 2018

The precipitation shield is moving out at a good pace this
morning. The rain/snow line made it approximately as far southeast
as a line from Paintsville to Jackson to Mount Vernon. Most
locations saw mainly reductions in visibilities, with perhaps a
touch of accumulation on grassy and elevated surfaces temporarily
in a few spots. Precipitation should be ending across the entire
area in the next few hours, with dry weather likely into this
evening and the overnight, as short wave ridging works into the
area aloft. Temperatures will be nearly steady the rest of today,
as northwest winds and persistent cloud cover combat the normal
diurnal rise through the rest of the day. Updates have been sent.

UPDATE Issued at 713 AM EST TUE NOV 13 2018

Did a quick update to ingest current observations and blend them
into the forecast. The forecast is on track thus far as the cold
front moves over eastern Kentucky. Light rain and drizzle have
been observed across the area through early this morning. Current
temperatures in southwestern Kentucky are around 40 degrees. A
rain/snow mix is possible in the northern Bluegrass region as
temperatures have dropped to just above freezing this morning
with frontal passage.


.SHORT TERM...(Today through Wednesday)
Issued at 403 AM EST TUE NOV 13 2018

Current surface analysis shows a cold front making its way across
eastern Kentucky. Light rain and drizzle have been observed across
the area with the progression of this front. Temperatures have been
slow to drop off tonight due to cloud cover, with temperatures
ranging from the upper 30s in the Bluegrass to low 40s in
southeastern Kentucky. Even with cloud cover and low ceilings so far
tonight, fog has developed in areas which has lead to lowered
visibilities. More rain is also incoming for the Bluegrass and
Cumberland Basin as shown by current radar. Therefore, have added
patchy fog in the grids through sunrise, mainly for the southeast.
As the cold front progresses to the east today, rain will taper off
from west to east. Most precipitation will exit eastern Kentucky by
late afternoon. Some residual precipitation is possible into the
evening in the high terrain of the far southeast. As temperatures
drop into the evening, a changeover to snow is possible as well.
However, no accumulation or impacts are expected. A brief respite
from the rain will take hold until Wednesday evening as an upper
level cutoff low, coupled with a surface low pressure system, moves
into Kentucky from the ARKLATEX region. This will bring increased
rain chances, and a changeover to snow as temperatures decrease,
moving from south to north into Wednesday evening.

Temperatures for the short term will continue to be below seasonal
normals. With cloud cover and frontal passage, high temperatures
today will only top out to near 40 degrees. Temperatures will drop
tonight, particularly in the northern Bluegrass where some clearing
in the clouds is expected. Lows will be in the low 20s in the north
and around 30 degrees in the south. High temperatures tomorrow will
be similar to today, only warming to be around 40 degrees.

.LONG TERM...(Wednesday night through Monday)
Issued at 403 AM EST TUE NOV 13 2018

The long term period will begin with a convoluted winter weather
setup across portions of eastern Kentucky. A closed upper low will
depart to northeast out of the Arklatex into the Lower Mississippi
River Valley by Wednesday night. This feature will aid in
developing a surface low across the Tennessee Valley and this will
track north and east with the deep upper level low. The counter
clockwise rotation of the surface low will lead to east and
northeast flow at the surface Wednesday night and this will advect
some colder air into the region. However, a strong warm nose will
exist not too far off the surface and this melting layer will lead
to a mostly liquid precipitation, but the cold air at the surface
will allow some of this to fall in the form of freezing rain.
There remains plenty of caveats with this storm system, How cold
will we actually get and right now that looks marginally cold,
This also brings up the important question of the resonance time
of the cold air, which looks like it will be short and Finally
there remains some timing differences among the guidance which
will impact the amounts of the types of wintry precipitation that
fall. The timing was mostly derived from the blended POPs with
some slight modifications, but felt this provided a reasonable
compromise at this point. The caveats were addressed by lowering
the overall ice accumulation amounts from the previous forecast,
and think that most places will see accumulations more limited to
elevated surfaces at this time. While there will be some cooling
from wet bulbing, the rate of precipitation could also limit the
amounts in the end. The overall highest threat at this time will
probably remain along and north of the Mountain Parkway.

We will see mostly rain on Thursday, as this cold core low
progresses into the lower Ohio Valley and warm air pushes into the
region. This upper level features will traverse across eastern
Kentucky and we will probably see some flakes mix with the rain
Thursday night before the upper level feature departs to the north
and east. We will see high pressure nose into the region by Friday
and keep the weather dry through early Sunday. The guidance does
diverge in solutions by the end of the weekend, but there will
probably be a clipper or upper level short wave that leads to a
low chance of POPs, as we move into early next week.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)

LIFR to IFR conditions were observed across much of eastern
Kentucky at TAF issuance. Light rain and drizzle have accompanied
a cold front that is progressing eastward across the area this
morning. A rain/snow mix is also possible this morning in the
northern Bluegrass as temperatures have dropped just above
freezing. This precipitation will taper off through the afternoon,
with most exiting the region by 21Z. Low CIGs have persisted
through the overnight but will slowly improve through the day
today as the cold front exits Kentucky. Some patchy fog and
lowered VIS were observed during the overnight as well, but VIS
has improved early this morning and is expected to improve through
the day. VFR conditions will return to all TAF sites later this
evening. Winds will generally be out of the north and range
between 5 and 8 knots for the TAF period.




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