National Weather Service Raw Text Product

258 
FXUS63 KLMK 240457
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
1156 PM EST WED JAN 23 2013

...Updated Aviation Discussion...

.Short Term (Tonight through Thursday night)...
Issued at 250 PM EST Wed Jan 23 2013

Sheared out disturbance aloft in the northern stream has generated a
ribbon of light snow/virga from northern Illinois to extreme
southern Ohio. Southern edge of the cloud cover currently extends
ESE from near Madison, IN into the northern Bluegrass region.
Shortwave trof axis will scoot east of the area later this evening,
pushing a weak reinforcing cold front south across Kentucky. Until
this happens we can't rule out a stray snow flurry, mainly across
the Bluegrass. Have also included a few flurries from the Bluegrass
to around Lake Cumberland due to the upslope influence behind the
front.

Cold air will be reinforced by a strong Arctic high that will
migrate quickly ESE across the Great Lakes Thursday. We will remain
far enough on the periphery of this high to keep winds up overnight,
so temps should not bottom out. Expect mins in the upper teens north
of the Parkways, and lower 20s farther south. Quiet weather on
Thursday under the influence of the high, but not much warming as we
will start out already mixed. Highs will struggle to crack 30.

Thursday night is trending slower, and therefore drier as the next
system tries to get organized. A Clipper will dive into the upper
Midwest and try to phase with a southern stream disturbance. Our
precip chances will depend on how quickly that phasing happens, and
at this point it appears that POPs will hold off almost until
daybreak on Friday. Surface temps will hold in the lower to mid 20s,
so precip type will be tricky. Warm nose looks to punch far enough
north to yield freezing rain along the southern tier of counties,
while it stays all snow north of the Western Kentucky and Bluegrass
Parkways. In between look for a transition zone with a mix of sleet
and freezing rain. However, POPs are just in the high-end chance
category, and QPF is quite light through 12Z Fri so we would not
expect to approach warning criteria by that time.

.Long Term (Friday through Wednesday)...
Issued at 303 PM EST Wed Jan 23 2013

The system for the end of this work week is continuing to trend
colder and drier. The bulk of the precipitation with this system now
looks to be Friday morning. Soundings do continue to show a dry
layer around 700 mb that never completely saturates. However, it
does still look like most of the area will have light snow during
the morning hours. Approximately along and south of the Cumberland
Parkway there will be a chance for more of a mix of precipitation as
a +2-3C warm layer aloft noses in. Right now it looks like sleet
will be likely with a chance for snow or freezing rain. This system
will move off to the east quickly through the afternoon and be
followed by a cold front. Precipitation chances will quickly end
from west to east.

Given the latest QPF amounts from the models, have trended snow
amounts down across the region. The highest snow totals look to be
east of Interstate 65 and north of the Cumberland Parkway. There one
to two inches will be possible. Elsewhere up to an inch of
accumulation will be possible. Though QPF amounts may be higher
across south central Kentucky, accumulations will be much less as
there will be a mix of precip types.

High pressure will build in Saturday with skies becoming partly
cloudy. Highs will be in the low 30s across the area. Saturday night
will see lows in the lower 20s to possibly upper teens.

The high pressure will slowly shift off to the east through mid week
next week. Winds will shift to southerly and warmer air will advect
into the Lower Ohio Valley. A couple of  systems will move north of
the forecast area Sunday through Wednesday. This will bring off and
on rain through this time period. Precipitation will initially move
in Sunday afternoon through Sunday night. This will likely start out
as a wintry mix. For now have gone with rain/snow in the grids, but
soundings do show a warm layer moving in aloft, so sleet or freezing
rain may be possible as well. However, by Monday temperatures should
warm enough that it will change over to all rain. A strong cold
front will eventually move through around the Wednesday time frame
finally bringing an end to the rain.

As mentioned above, warmer air will build in to the area early next
week. Temperatures on Monday look to rise into the upper 40s to
around 50 while Tuesday and Wednesday could be in the mid to upper
50s. Lows will be in the 40s.

&&

.Aviation (06Z TAF Issuance)...
Issued at 1156 PM EST Wed Jan 23 2013

A large dome of high pressure moving from Minnesota to North
Carolina will keep our weather quiet for this TAF period.  The
models are suggesting that a broken MVFR ceiling may move through
during the 08Z-13Z time frame this morning, but right now there's
enough doubt in that solution to keep the TAFs VFR.  Will keep an
eye on cloud conditions over Illinois and Indiana and amend if
necessary.

Pre-dawn breezes will be from the northwest, then switch to the
northeast for the daylight hours, and then become more ESE by
Thursday evening as that high moves by.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$


Short Term.......RAS
Long Term........EER
Aviation.........13