869 
FXUS63 KLMK 091746
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1246 PM EST Wed Jan 9 2019

...Updated Aviation Discussion...

.Short Term...(Today and tonight)
Issued at 245 AM EST Wed Jan 9 2019

A mixy cold advection regime will dominate today, with fast NW flow 
through a deep layer. While it will be much less windy than Tuesday, 
we still expect sustained 15-20 mph winds with gusts in the 25-30 
mph range. Temps will not recover much given the already unstable 
boundary layer, so expect to stay in the 30s all day with wind chill 
values in the 20s. Most of the area should see plenty of sunshine, 
but as the mid-level flow takes on a more northerly component, 
expect some strato-cu to pinwheel south into the Bluegrass region. 
Could even see a few stray flurries out of these clouds but nothing 
measurable.  

Look for diminishing winds tonight, which will allow temps to drop 
to the coldest readings in about a month. Most locations should be a 
couple degrees either side of 20.

.Long Term...(Thursday through Tuesday)
Issued at 245 AM EST Wed Jan 9 2019

Cool, dry weather continues into Thursday as a strong Canadian high 
to our north influences the region. Highs may only briefly reach 
above freezing during the late afternoon, but should quickly drop 
after the sun sets. Overnight lows look chilly, dropping into the 
low 20s. 

By Friday, a shortwave ejects off the southern Rockies/Plains and 
moves toward our region. Plentiful moisture and strong isentropic 
lift will aid in the development of precipitation ahead of this 
system starting as soon as Friday night. Precipitation coverage 
should be widespread by sunrise Saturday morning, and likely 
continue into Sunday morning or afternoon. 

Things get interesting in regards to the temperature profiles with 
this system. Cold air will be in place to start things off as snow 
for most folks, but the placement of the trough/low promotes warm 
air advection (WAA) in the surface-700mb layer for the majority of 
the event. This will result in a transition to a cold rain (with 
perhaps a brief wintry mix early in the transition) Saturday morning 
starting in southern KY. As the warmer air advects northward, 
additional areas across central KY should switch over to rain during 
the day Saturday. At this point in time, areas along and north of 
the I-64 corridor may have enough cold air locked in place that 
despite ongoing WAA, the ptype remains mostly snow for the event, 
with only a brief transition to rain possible. It is also here that 
the best potential for accumulating snowfall remains. As the system 
departs Sunday, we could see rain switch to snow across portions of 
central KY as colder air wraps around the low. We're still several 
days out from seeing any potential impacts from this system, and 
there are still a lot of variables that will be fine-tuned in the 
coming days that impact wintry accumulations (track of system, 
strength of WAA, surface temps, etc). Stay tuned!

Canadian high pressure builds in behind the system early next week, 
resulting in cool and dry weather through at least midweek.

&&

.Aviation...(18Z TAF Issuance)
Updated at 1245 PM EST Wed Jan 9 2019

VFR conditions are expected to prevail at all TAF sites during this 
forecast period as high pressure builds in from the northwest. 
Currently a stratocumulus deck is streaming into the region from the 
north. With the tight pressure gradient over the region, wind gusts 
around 20-25 kts will continue into the early evening. Lighter winds 
around 5-10 kts are then expected into tomorrow with a high cloud 
deck moving in by morning.

&&

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

$$

Short Term...RAS
Long Term...DM
Aviation...JMB