Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 190709
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
309 AM EDT Sun Oct 19 2014
.SHORT TERM (Now through Monday)...
Issued at 309 AM EDT Sun Oct 19 2014
Low clouds continue to linger over the region with moisture mostly
trapped below 925 mb. The NAM has handled these low clouds the best
for the past 24 hours, and would suggest they will linger along and
east of I-65 into the mid and late morning hours at least. They
could hold on in our NE (including Lexington) until mid to late
afternoon. This matches up with 0-3 km temperature forecasts showing
thermal ridging only slowly pushing east during this time, and no
other mechanism to eradicate them other than daytime mixing.
Therefore, will be pretty pessimistic with the cloud forecast and
today`s temperature forecast across our north and east. Also, have
removed any chances for patchy frost early this morning as
temperatures are currently running in the 46-51 range.
Surface high pressure settles over the area today with benign
northwest flow aloft. Expect highs to reach up around 60 in our SW,
and only reaching the mid 50s in our NE due to the cloud cover.
Focus will shift to another PV anomaly dropping SE in the northwest
flow late tonight. Expect an increase in upper level clouds this
evening ahead of the feature, however as we near sunrise on Monday
some slight chances for a measurable rain shower will be possible
across southern Indiana. Not totally sold on the prospects of
measurable precipitation as organization of "deeper" moisture
appears in question. The NAM (which has performed well over the past
24 hours) keeps us dry, so will hesitate on any higher pops for now.
Either way, the best chance for a light rain shower will be across
our northeast CWA from early Monday morning through the day. Do
expect a warm-up for Monday with highs reaching the low and mid 60s
on steady SW flow at the surface.
.LONG TERM (Monday Night through Saturday)...
Issued at 245 AM EDT Sun Oct 19 2014
Amplified upper pattern will have the Ohio Valley in deep northerly
flow Monday night and Tuesday, keeping us cloudy and a bit
unsettled, especially across the Bluegrass region. Even with the
cold front already through, and most of the mid/upper forcing
remaining to our north and east, models show a decent moisture plume
off Lake Michigan. Will keep small POPs and low QPF in through
Tuesday, with the best chance over the Bluegrass and into the higher
terrain near Lake Cumberland.
Closed upper low is slow to exit the mid-Atlantic but a shortwave
ridge aloft tries to build in by Thursday. Canadian surface high
will nose south into the Ohio Valley, providing dry weather and cool
temps. Eventually a chunk of this high will break off the parent
high and modify over the Ohio Valley. By the weekend temps should
recover to climo or just a couple degrees warmer. No precip in the
forecast as a late-week upper system is shunted well into the Deep
South without the Gulf ever opening up.
Only real chance for frost will be on Thursday morning, when the
surface ridge is closest to central Kentucky. Current forecast is
for upper 30s in much of the area, so it wouldn`t take much of an
adjustment for frost to be in play, especially for rural locations.
.AVIATION (06Z TAF Update)...
Updated at 101 AM EDT Sun Oct 19 2014
The main question for the early morning hours continues to be a
stubborn stratocu deck plaguing the TAF sites. Will continue with
the pessimistic forecast as higher resolution models indicate that
low clouds will survive at SDF/LEX past sunrise. Also, forecast
models usually show a bias toward clearing low clouds out too
quickly. Ceilings are currently just above the MVFR/VFR threshold,
however do expect them to drop around or after 4 AM EDT, likely
lasting through mid to late morning. The deck is then expect to rise
and scatter as we head into the afternoon hours. Surface winds will
be light and variable during this time as surface high pressure
settles over the area.
Will keep a more optimistic forecast for the BWG area, where only
some light fog/mist and a few/sct low clouds should impact the
terminal until just after sunrise. Thereafter, expect few/sct clouds
with light and variable winds.