Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 161128
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
628 AM EST Tue Dec 16 2014

...Updated Forecast and Aviation Discussions...

...Forecast Update...
Issued at 625 AM EST Tue Dec 16 2014

The cold front was approaching east central KY as of 615 am this
morning and will work east through the area over the next few hours
switching winds to the west and ending the area of steady rain
showers.  Expect gusty westerly winds for the rest of the day with
on and off rain showers or drizzle through this evening.  Removed
t-storms, updated POP timing, and tweaked temps/dewpts with this
update.  Temps still look to fall through the 40s throughout the day.

.SHORT TERM (Now through Wednesday)...
Issued at 310 AM EST Tue Dec 16 2014

An occluding low pressure system will move from Iowa/Illinois this
morning eastward through the Great Lakes today.  This weather
system`s cold front was near southwest Indiana and west central
Kentucky early this morning and will continue eastward progress
through the forecast area through mid morning.  Ahead of the front,
expect rain showers with isolated t-storms.  Although these t-storms
look to remain shallow and elevated, it isn`t out of the question
for one of them to mix down wind gusts as high as 30-35 mph.  Some
storms have exhibited a decent shear zone early this morning which
may promote gustier winds.  The t-storm activity has largely been
aided by mid and upper level jet support which will decline around
sunrise.  Thus, will remove the t-storm mention after 12Z this
morning.

For the rest of the day, expect isld-sct rain showers with some
drizzle possible on the back side as well.  Weak lift will continue
ahead of a secondary sfc trough expected to cross the area this
evening.  After the secondary trough passes through along with the
main upper trough axis this evening, precip chances will cease.
Soundings indicate that precip will stay in liquid form post-frontal
throughout the day today.  Also temps will be on the decline
throughout the day with the early cold front passage.  Temps will
start the day in the upper 40s and lower 50s falling into the mid
40s for this afternoon.

S-SW-W winds will be gusty today with gusts in the 20-30 mph range
outside of any convection as we sit in a tight sfc pressure
gradient.  Wind gusts will decline this evening.

Tonight CAA will continue with another slug of colder air behind the
secondary sfc trough.  Expect lows to fall into the low to mid 30s
with continued cloudy skies.

Wednesday sfc high pressure will work into the region.  We should
see cloud cover thin or maybe even get some breaks in the clouds Wed
afternoon.  Still with at least good morning cloud cover, high temps
should hold in the mid 30s to around 40 Wed afternoon.

.LONG TERM (Wednesday Night through Monday)...
Issued at 300 AM EST Tue Dec 16 2014

The upper air pattern late Wednesday will feature a broad 500mb
trough centered over Arizona with a strong southwesterly jet
extending northeast across the southern plains and the Ohio Valley.
A weak upper wave with no associated surface reflection will move
across Arkansas and southern Missouri Wednesday night spreading
light, possibly wintry precipitation across the lower Mississippi
Valley. This wave will weaken as it approaches confluent 500mb flow
and dry air across the Lower Ohio Valley. Guidance is quite
consistent in the erosion of any precipitation as it tries to move
northeast towards northern Kentucky. However if any light
precipitation makes it into the southern and central Commonwealth
early Thursday, forecast soundings hint at snow, or a rain snow mix.
With forecast lows early Thursday falling to near 30 across our
south early Thursday, some light wintry accumulations are possible.
Highs later Thursday will reach the mid to upper 30s.

Weak high pressure will move over Lake Michigan late Thursday. Light
winds will continue Thursday into early Friday across the Lower Ohio
Valley with seasonable temperatures. The prospects for any sun are
not too good for late Wednesday through early Saturday, except for
possibly Friday afternoon, when partly cloudy skies are possible.
Expect highs Friday in the lower 40s.

The 500mb trough over Arizona mentioned earlier will translate east
across Arkansas late Saturday. Weak low pressure will form early
Saturday across Louisiana, with a surface trough extending
northeastwards into western Tennessee. Widespread precipitation will
move across the northern Gulf States and the Tennessee Valley
beginning early Saturday. The latest ECMWF has become more
progressive and farther south with the track of the surface low.
Kentucky will lie in the northern edge of a broad precipitation
shield resulting from isentropic lift ahead of the approaching upper
trough. Soundings and temperatures support snow along and north of
the Ohio River, with a possible rain/snow mix across the central
portions of the Commonwealth. True arctic air is missing with this
system, however, the placement of Kentucky within the northern edge
of the precipitation shield does allow the possibility of some
wintry accumulations Saturday. Highs Saturday will potentially reach
the mid to upper 30s, with lows falling into the upper 20s early
Sunday.

High pressure will nose into the Lower Ohio Valley as precipitation
moves east of the area early Sunday. Some partial clearing is
possible for late Sunday into Monday. Temperatures will stay
seasonably cool with highs Sunday and Monday hovering not too far
from 40.

&&

.AVIATION (12Z TAF Update)...
Issued at 605 AM EST Tue Dec 16 2014

A low pressure system will continue to occlude as it moves east
through the Great Lakes today.  The back edge of the rain associated
with this system will push through LEX between now and 13Z producing
some -SHRA.  A rumble of thunder isn`t out of the question but the
trend for t-storms has been farther north over the last few
hours. The cold front has made it through SDF/BWG and will push
through LEX by 13Z. VCSH or -DZ will continue to be possible at all
TAF sites throughout much of the day in the wake of the cold front.
Wind gusts will continue between 18-22 kts throughout the day and
should subside this evening.  Flight conditions are expected to
remain MVFR over 2 kft for the most part.  However, some model
guidance hints cigs will go below 2 kft especially at SDF/LEX at
some point today or tonight.

&&

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

$$

Update.........AMS
Short Term.....AMS
Long Term......JSD
Aviation.......AMS




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