Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 060615
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
115 AM EST Tue Dec 6 2016

.UPDATE...
Issued at 950 PM EST MON DEC 5 2016

With the upper low still across east Texas, bulk of the lift
remains across the lower Mississippi Valley. Given the lack of
lift until late tonight or even after daybreak Tuesday, combined
with downslope winds, have decreased rain chances considerably for
tonight. Still looking at rainfall amounts of 0.75 to 1 inch out
of this system, but this will mainly all fall tomorrow morning and
afternoon.

UPDATE Issued at 731 PM EST MON DEC 5 2016

Broken band of rain extending from the lower Mississippi Valley
into the Tennessee Valley continues to look rather disorganized as
it journeys northeastward. With the upper low just now pushing
into east Texas, lift ahead of the warm/moist conveyor belt will
steadily make headway toward the Tennessee and eventually
Cumberland Valleys. Increasing lift associated with this feature,
along with isentropic upglide, will not take place until after
midnight. Thus, have slowed timing of the best rain chances down
to account for this, along with backed easterly/downslope winds
remaining in place on the eastern side of the approaching surface
low. These will not veer south/southwesterly until Tuesday
morning, keeping the best rain chances and highest rainfall
amounts in check until then. Have also updated temperatures as
slower progression of low clouds from the southwest will likely
allow valleys in the Big Sandy region to cool off early this
evening prior to the onset of warm air advection.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 300 PM EST MON DEC 5 2016

An area of low pressure aloft is forecast to move out of the
southern Plains/western Gulf coast region this evening, and will
be our primary weather maker through tomorrow night. Most of the
latest model data is suggesting that precipitation onset will
still be a couple of hours later than the night shift forecast was
indicating. The new forecast will reflect a blend of the latest
model data with precipitation onset anticipated around 1Z this
evening in our far southern counties, or roughly two hours later
than previously forecast. Based on the expected temperature
profiles, precipitation will be in the form of all rain across
eastern Kentucky. The best chance for rain will occur from late
tonight through Tuesday afternoon. The rain should begin to taper
off Tuesday afternoon and evening, with the last rain showers
exiting the area between 9 and 10Z Wednesday. Area wide we can
expect around an inch of rain from this event.

Temperatures are expected to run at or slightly below normal
through tonight, with a non diurnal temperature progression
tonight. There will likely be a period of time tonight during
which temperatures actually begin to increase, as winds also
increase and shift more to the south and widespread precipitation
sets in. Highs on Tuesday are expected to top out in the 50s,
with lows in the 40s tonight and the 30s Tuesday night.

.LONG TERM...(Wednesday through Monday)
Issued at 328 PM EST MON DEC 5 2016

We transition to a much colder weather pattern to end the work
week as a deep, but transient, trough digs into the Ohio Valley.
Models usher in this colder airmass without much precipitation.
However, we come under the influence of the right entrance region
of a stout 150kt upper level jet as the cold front works through
Thursday morning and models hint that this could force some light
snow and/or rain Wednesday night into Thursday morning. Will keep
PoPs rather low as moisture is limited. Isolated snow showers and
flurries will remain possible Thursday night into Friday with
strong cold advection wringing out any lingering moisture.
Temperatures will likely not rise out of the 20s on Friday.

Cold high pressure settles into the region Friday night and this
will likely be our coldest night. However, models show the
potential for some high clouds to interfere with our radiational
cooling. Nonetheless, temps in the teens are a good bet for just
about everyone.

Models show a fast transition to southwest flow aloft by Saturday
night in advance of a shortwave digging into the northern Plains.
This will result in increasing clouds and precipitation chances
late in the weekend. Timing remains questionable with this system
with large differences in the modeling so stayed close to the
blended model guidance. However, 60-70 PoPs on Sunday seemed a bit
high with the uncertainty involved, so dropped them down into the
chance range. Current forecast timing would introduce the threat
for a mix of rain and snow at onset late Saturday night/early
Sunday morning, but the bulk of the precipitation Sunday into
Monday should be rain.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 114 AM EST TUE DEC 6 2016

Conditions are beginning to deteriorate at TAF issuance,
especially across the southern portion of the state. KSME has now
fallen to MVFR, and KLOZ will be soon to follow over the next
hour or so. High clouds still persist at the remaining TAF sites,
but should begin falling quickly to MVFR generally after 8Z at
KJKL and closer to 9Z at KSYM. Rainfall will be on the heals of
the CIG drop, expected to start to KSME and KLOZ over the next
couple of hours as well. Ceilings will likely lower further to IFR
and possibly LIFR by Tuesday morning as rainfall becomes more
widespread. Visibilities will also decrease to MVFR and
potentially IFR as rain falls. Should see the bulk of the rain
taper off by late afternoon, allowing visibilities to increase to
VFR criteria. However, IFR ceilings look to be a good bet through
the end of the TAF period (6Z). Winds will increase to 5-10 knots
through the rest of tonight, while veering southeasterly. Will see
these veer further to the west/southwest this afternoon, with
speeds increasing to near 10 knots with higher gusts during the
latter portion of the afternoon. All this as a cold front gets set
to move through the Ohio Valley and Commonwealth. Additionally,
southeasterly low level wind shear near 35-40 knots may become an
issue tonight across far southeast Kentucky.

&&

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

$$

UPDATE...GUSEMAN
SHORT TERM...AR
LONG TERM...ABE
AVIATION...JMW



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