Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 150519
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1219 AM EST Mon Jan 15 2018

...Updated Aviation Discussion...

.Forecast Update...
Updated 822 PM EST Sun Jan 14 2018

Light snow was common throughout Illinois this evening in a warm
advection wing of a clipper. Light snow was also starting to reach
the ground in the western half of Indiana. Arctic front was evident
in surface obs, with much colder air pushing south toward Iowa and
Nebraska.

By 06z, the DGZ saturates across all of central KY/southern IN, and
flurries should be more common. However, low levels still look to
stay fairly dry across the south. But occasional light snow showers
are still a good bet across southern IN and northern KY late tonight
and early Mon. Some spots could see a quick dusting. No notable
forecast changes this evening. Surface temps should slowly rise
after midnight.

&&

.Short Term...(This evening through Tuesday)
Issued at 320 PM EST Sun Jan 14 2018

...Another round of light accumulating snow is expected through
Tuesday...

We have quiet weather across the region this afternoon with high
pressure stretching across the lower Ohio Valley. Some high clouds
are streaming in and temps this afternoon remain chilly in the teens
to low 20s. This weather will not last long, however, as another
round of snow is expected for the region beginning tonight, but
mainly Monday though Monday night.

For tonight, clouds will be on the increase as the next system
approaches from the west. A weak warm front and upper level
disturbance will move through the region tonight. This will lead to
a round of flurries and snow showers overnight. Looking at
reflectivities from high resolution models, it does look like there
is the potential for snow flurries down to the KY/TN border. Further
to the north isolated to scattered snow showers are expected along
with some flurries. Snow accumulations, if they occur will likely be
confined to along and north of the I-64 corridor with a couple of
tenths of an inch possible. The highest accumulations look to be
across our northern tier of counties in southern IN from Dubois to
Jefferson along with Trimble county in KY. Some in these areas could
see up to half an inch of snow overnight. This snow should taper off
before daybreak.

The next round of snow will move in tomorrow morning as a cold front
approaches and moves through the region. This snow should move into
southern IN by mid morning and approach the Ohio River by mid day.
It will then spread into southern and eastern KY by mid to late
afternoon. This snow may weaken a bit as it heads east through the
day. Snow looks to come to an end across southern IN and portions of
central KY by late afternoon to early evening. However, as we go
into the overnight hours, the area of snow showers looks to stall
out across east and south central KY. It will be enhanced overnight
as the entrance region of an upper level jet rotating in provides
divergence aloft. Thus, snow looks to reintensify and then linger
into Tuesday morning across this region.

All in all, we have 1-2 inches of snow accumulation forecast for
this event across the region. Thus, a Winter Weather Advisory is
being issued this afternoon. This Advisory will be split into three
segments. The first one will cover the area across southern IN
described above which could see up to half an inch of snow tonight.
This Advisory will cover both the event tonight and the one
tomorrow. The second segment for portions of southern IN and central
KY will begin at 15Z tomorrow as the main snow is not expected to
begin until after the morning commute. This segment will go until
03Z, but may be able to be ended earlier. The third segment will be
for east and south central KY and will begin at 18Z Monday and run
until 15Z Tuesday. This is due to the fact that the snow looks to
reintensify overnight Monday night into Tuesday.

Snow should end by Tuesday afternoon, but the cold will remain. Lows
Tuesday morning will range from near zero in southern IN to the
teens in the Lake Cumberland region. Wind chills will be in the
negatives across portions of the region. Highs on Tuesday will top
out in the teens to around 20.

.Long Term...(Tuesday Night through Sunday)
Issued at 300 PM EST Sun Jan 14 2018

Tuesday Night - Wednesday...

With a strong upper trough and vort max slowly pushing through the
region, and plentiful low level moisture, feel that at least
flurries will continue Tue night through Wed morning. With snowpack
and a very cold airmass in place, Wed morning will be quite cold
with dangerously cold wind chills.  Expect lows in the 0 to 5 degree
range and just enough wind to drop the lowest wind chill values into
the -10 to 0 range.  Skies will begin to clear Wed afternoon with
highs reaching the lower 20s.

Thursday - Sunday...

Thursday and Friday will feature dry weather and a "warm-up".  While
temps Thu morning will still be very cold in the single digits,
highs Thu afternoon will reach the lower 30s under mostly sunny
skies.  The warming trend will continue Fri as southerly flow
strengthens.  Highs look to reach the 40s Fri.

The next weather system will impact the region this weekend. We`ll
see low chances for rain showers starting Sat in a moist southerly
flow with weak isentropic lift.  A strong cold front will approach
the area Sun/Mon bringing steady light to moderate rains with a
rumble of thunder not out of the question.  Temps will warm into the
50s Sat/Sun ahead of the front!

&&

.Aviation...(06Z TAF Issuance)
Issued at 1219 AM EST Mon Jan 15 2018

A weak disturbance will move northeastward across the region over
the next few hours.  This will bring some light snow showers to
mainly HNB/SDF/LEX.  Some temporary reductions down to MVFR are
expected as the snow showers move through.  We should see a bit of a
lull in the activity toward dawn.  However, a strong cold front will
drop into the region from the northwest and additional snow showers,
some heavy at times will pass through the region.  MVFR cigs are
likely to prevail during the afternoon, but the heavier snow showers
may result in temporary reductions down to IFR.  The snow showers
will bring some light accumulations to the terminals.

The best time frame for accumulating snow/MVFR at each TAF site
tomorrow are:

HNB 15Z-22Z
SDF 16Z-2Z
BWG 19Z-6Z
LEX 22Z-8Z

In addition, SW-W winds will be gusty (18-22kts) tomorrow afternoon.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...Winter Weather Advisory until 4 PM EST this afternoon for
     INZ076>079-083.

     Winter Weather Advisory from 10 AM EST /9 AM CST/ this morning
     to 10 PM EST /9 PM CST/ this evening for INZ084-089>092.

KY...Winter Weather Advisory until 4 PM EST this afternoon for KYZ032.

     Winter Weather Advisory from 1 PM EST /noon CST/ this afternoon
     to 10 AM EST /9 AM CST/ Tuesday for KYZ036-037-040>043-
     046>049-054>057-064>067-070>078-081-082.

     Winter Weather Advisory from 10 AM EST /9 AM CST/ this morning
     to 10 PM EST /9 PM CST/ this evening for KYZ023>031-033>035-
     038-039-045-053-061>063.

&&

$$

Update.......AMS
Short Term...EER
Long Term....AMS
Aviation.....MJ



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