Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 101715
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1215 PM EST WED FEB 10 2016

...Updated Aviation Discussion...

...Forecast Update...
Updated at 1050 AM EST Wed Feb 10 2016

12Z models coming with a little more light snow totals in our
southwest forecast area, so bumped up percentages down there late in
the afternoon and into the evening hours. Even with light QPF, high
snow ratios would mean a few tenths of an inch of dry snow could
fall, should the edge of the snow shield make it into our area.

Updated at 915 AM EST Wed Feb 10 2016

First light visible shows the edge of deeper moisture now over the
Louisville metro and heading east. After collaboration with JKL/ILN
decided to go ahead and extend the winter weather advisory across
our east until 18Z, to allow for that moisture to get out of here,
but the rest of the area should see it drop off at 15Z.  Next up we
will be watching the snows over IA/MO to see how much it gets into
our southwest forecast area by late this afternoon. Current thinking
is this could drop a few tenths of an inch of snow in our southwest
this evening. Updated products out shortly.

.SHORT TERM (Now through Thursday)...
Issued at 310 AM EST Wed Feb 10 2016

...Snow Showers Ending Late This Morning...

The main forecast concern in the short term is on the lingering snow
showers this morning.

As of 3 am, latest water vapor imagery with 500 mb heights showed
the anomalous trough across the eastern CONUS. One embedded
shortwave was rounding the edge from central Illinois into west
central Kentucky. At the surface, plenty of clouds, moisture and
cyclonic flow have kept scattered to numerous snow showers spinning
through, evident by the regional radar mosaic. Temperatures were
mainly in the teens with west to northwest winds. This has created
wind chills in the single digits. A cold, snowy mid February morning.

Within these snow showers, there have been embedded heavier bursts,
which have locally produced a quick 0.5 to 1.0 inch since late last
evening and early this morning, along with visibility down to around
1 mile. The light, fluffy snow will continue to accumulate on
surfaces, and any untreated and/or less traveled roads will likely
be slick for the morning commute. As a result, will continue the
Winter Weather Advisory through 10 am EST / 9 am CST. Additional
accumulations will be under an inch generally in most spots.

The main upper level forcing for these snow showers will finally
track east of the area by mid day. Soundings show the mid levels
drying out considerably and this will work down, effectively
shutting off the moisture, giving way to just flurries for the
afternoon. Highs today will be in the low to mid 20s.

As soon as this weather system clears out, another fast moving upper
level shortwave will dive toward western Kentucky late this
afternoon through early Thursday morning. This feature is currently
in North Dakota producing light snow. As it tracks toward our area,
however, it will weaken and lose some of its moisture. Forecast
guidance continues to suggest very light QPF is possible across our
far southern and southwest counties from this evening into tonight.
A quick coating of snow, up to 0.5 inch locally, is possible. Across
southern Indiana and north central Kentucky and the Bluegrass
region, plan on just clouds or perhaps an isolated flurry. Lows will
be in the teens to around 20.

.LONG TERM (Thursday night through Tuesday)...
Issued at 310 AM EST Wed Feb 10 2016

The main forecast concern in the long term is on snow chances
Friday/Friday evening and the potential for another winter system
late this weekend into early next week.

For Thursday and Thursday night, persistent northwest flow aloft and
surface high pressure will make for a seasonably cool but dry day
across the lower Ohio Valley. Plan on highs in the upper 20s across
southern Indiana to mid 30s near the Tennessee border. Winds will be
light and there should be a mix of sun and clouds, especially by
afternoon. Plan on a cool night with lows in the teens.

10.00z guidance continues to show a fast moving upper level system
diving southeast toward the area on Friday. Overall, this system has
slightly better forcing and more moisture compared to the system
coming through this evening/tonight. Model QPF remains under 0.05
inch but this has the looks of another high SLR, low QPF snow event.
Placement and timing details are still not quite ironed out, but
much of southern Indiana and central Kentucky could see light snow
during the day into the evening hours. Accumulations at this point
look to be under 1/2 inch.

Strong Canadian surface high pressure then drops south Friday night
through Sunday morning, bringing unseasonably cold air to the area.
A dry forecast is in store, but plan on highs Saturday only in the
low/mid 20s with morning temperatures Sunday in the low teens. Some
of the typically colder Bluegrass spots may drop into the single
digits. Wind chill values during the early morning hours will hover
around zero at times.

10.00z deterministic and ensemble data continue to show another
storm system possible for Sunday night into Monday. Compared to what
we`ve had this week, this system would have more moisture and also a
more developed surface low. Model differences in placement, phasing,
temperatures and timing are all still there but there is potential
for accumulating snow. At this point, the northern half of the
forecast area /north of KY parkways/ look to be cold enough for the
duration to support all snow. For now, used a generic rain/snow mix
based on hourly temperatures as details can be ironed out in the
next few days.

&&

.AVIATION (18Z TAF Update)...
Updated at 1215 AM EST Wed Feb 10 2016

Scattered snow showers will linger through mid afternoon. Areal
coverage has already diminished since this morning, and will
continue to do so this afternoon. Despite VFR prevailing conditions,
ceilings can still dip into MVR category at times, and VSBYs could
actually drop into IFR briefly with some of the heavier snow
showers, especailly at LEX.

The snow showers should dissipate with the setting sun.

Westerly winds of 8-12 kts will decrease this evening.

&&

.LMK Watches/Warnings/Advisories...
KY...Winter Weather Advisory until 1 PM EST /noon CST/ this afternoon
     for KYZ035>037-039>043-046>049-054>057-064>067-077-078.

IN...NONE.
&&

$$

Update.........RJS
Short Term.....ZT
Long Term......ZT
Aviation.......JBS


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