Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 060530

Area Forecast Discussion
National Weather Service Louisville KY
1230 AM EST SAT FEB 6 2016

...Updated Aviation Discussion...

.SHORT TERM (Now through Saturday Night)...
Issued at 240 PM EST Fri Feb 5 2016

No major weather concerns tonight or Saturday as the region lies
under the influence of weak ridging at the surface and aloft and
with a very dry air mass in place, just expecting increasing high
clouds at times through the period. Plan on lows tonight to fall
into the mid 20s to around 30, coldest in the valleys and across the
Bluegrass region.

Expect a seasonable and dry Saturday with a mix of clouds throughout
the day. Temperatures will rise into the upper 40s to low 50s with
south winds. Saturday night lows will be right around freezing.

.LONG TERM (Sunday through Friday)...
Issued at 305 PM EST Fri Feb 5 2016

The main forecast concern in the long term is precipitation chances,
accumulating snow potential and temperatures next week.

Southwest flow aloft and at the surface on Sunday will allow
temperatures to rise well into the 50s region wide. This is in
advance of the upper trough and surface front that is expected to be
on our northwest fringes by Sunday night.

Weak warm advection and isentropic lift ahead of the surface low
will bring a band of precipitation across the area Sunday night into
Monday morning. Soundings show that temperatures will be warm enough
initially to support rain to maybe a rain/snow mix in the north as
evaporative cooling effects take place. The main slug of cold air
associated with the upper trough doesn`t arrive until Monday late
morning or afternoon, which is when temperatures begin to crash and
soundings support all snow. Depending on the frontal passage timing
Monday, a non-diurnal temperature curve may be needed (maybe more
so in southwest or south central Indiana).

The closed upper low sets up directly overhead Monday night through
Wednesday with various shortwave troughs pivoting through. Model QPF
looks to be light overall /0.2 to 0.3 over 48 hours/ but with snow
ratios likely in the 15-20:1 range at times, a few inches of
accumulation will be possible over the course of 2 to 3 days. The
highest amounts will likely be from southeast Indiana to the
Bluegrass region in the favored cyclonic flow area. Some travel
impacts are possible at times next week. Beyond Wednesday,
deterministic models vary considerably but hint at another fast
moving shortwave trough coming through northwest flow in the
Thursday/Friday time frame.

As far as POPs, a model consensus continues to come in too low /20
to 30 percent/ so bumped this back up to 40 to 60 percent range.
This probably will need to be increased further Monday night into
Tuesday night.

Temperatures Tuesday through Thursday will be tricky depending on 1)
cloud cover (especially at night) and 2) potential snow cover. A
model consensus trended somewhat cooler, so have largely stayed with
this idea, especially for the Wednesday-Friday time period. Overall,
the coldest days of the week look to be Tuesday and Wednesday
/highs in the 20s to near freezing/ with the coldest mornings
Wednesday and Thursday /lows in the teens/.


.AVIATION (06Z TAF Update)...
Updated at 1225 AM EST Sat Feb 6 2016

Sct-bkn high level cirrus clouds and few-sct mid-level clouds will
prevail through the forecast period, but these will have little/no
impact as conditions remain VFR through the period at SDF, LEX, and
BWG. Light/calm surface winds overnight will be southwest at 4-8 kts
on Saturday then south-southwest at 5 kts or less Saturday night.


.LMK Watches/Warnings/Advisories...


Short Term........ZT
Long Term.........ZT
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