Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 050233
Area Forecast Discussion
National Weather Service Louisville KY
933 PM EST THU FEB 4 2016
Updated at 930 PM EST Thu Feb 4 2016
Clouds have pretty much exited the Bluegrass region, and the rest of
the night looks clear. Current forecast is on track, but a quick
update coming to clean up evening wording in the east.
.SHORT TERM (Now through Friday Night)...
Issued at 300 PM EST Thu Feb 4 2016
Large area of low clouds will continue to slowly move out of the
region this afternoon and this evening. The clearing line is just
west of I-65 now with mostly sunny skies noted across the western
third of KY. Temperatures remained in the lower 30s in the cloud
cover, but have rebounded slightly across far western KY in the
sunshine. Given the slower clearing trend, we`re likely to see our
highs for the day in the next hour or so. We`ll probably see a few
ice pellets or snow flurries across the north-central and east-
central sections as the clouds clear out. Temperatures this evening
will drop into the upper 20s. With expected clearing overnight and
light winds, we`ll see overnight minimum temps drop into the lower
20s out across the Bluegrass region with 24-27 degrees elsewhere
across the district.
Dry conditions are expected for Friday as a weak front pushes
through the region. However, moisture will be very lacking and only
a slight increase in cloud cover is expected. High temperatures
will range from the lower-mid 40s in the east with mid-upper 40s in
the west. High pressure will then build into the region for Friday
night with lows cooling into the upper 20s.
.LONG TERM (Saturday through Thursday)...
Issued at 322 PM EST Thu Feb 4 2016
At the beginning of the period, we`ll see an upper trough cross the
region on Saturday. This feature will cut off across the deep south
and spawn a coastal storm just off the Carolinas early Sunday
morning. Moisture will be rather scant, so we`re just expecting
some cloudy skies as this feature pushes through the region. Highs
Saturday will warm into the upper 40s to around 50 and overnight
lows will cool into the lower 30s by Sunday morning. Clouds will be
on the increase by Sunday as the next wave approaches from the
northwest. Highs Sunday look to top out in the upper 40s to the
lower 50s region wide.
By Sunday night, the global models are in general agreement with a
strong upper trough dropping out of the Midwest and then closing off
across the Ohio Valley in the Monday through Tuesday night time
frame. While the models agree with the trough closing off, there
remains considerable differences in how far south the low tracks and
cuts off before heading off to the east by early Wednesday. The
Euro and Canadian runs are more north/northeast with their tracks,
keeping the best moisture and colder air to our north and east.
Meanwhile, the GFS solutions continues to be the most wound up,
stronger, and furthest south and southwest in the guidance envelope.
Using a blend of the Euro/GEM/GFS keeps the ongoing forecast rather
consistent though it does warrant an increase in precipitation
chances and cloud cover. Precipitation is likely to break out
Sunday night across the region. Some warm air advection on the
south side of the system will likely keep precipitation in a mixed
state (Rain/Snow) through much of the night as temperatures remain
around the freezing mark. Temperatures will see a diurnal spike on
Monday with upper 30s but then temperatures should crash during the
evening hours and then remaining cold through Tuesday night. Lows
Monday night will drop into the lower-mid 20s with highs on Tuesday
only warming into the mid-upper 20s. Tuesday night lows will cool
into the teens.
With these temperatures forecasts in mind, predominant precipitation
type will be in the form of snow Monday night through Tuesday night.
QPF amounts are not overly impressive compared to a dynamic synoptic
system with a good moisture feed off the Gulf or the Atlantic.
Nonetheless, with a very cold temperature profile in place in the
troposphere, snow ratios will be in the 17-22:1 range, so with even
light QPF amounts, a couple of inches of snow will be possible by
the time the precipitation ends late Tuesday night.
The upper low/trough axis is forecast to lift out on Wednesday which
will bring an end to the precipitation along with clearing skies.
Temperatures will be dependent on snowcover. Since we believe that
we`ll have some on the ground, we have trimmed back temperatures
slightly with highs in the mid-upper 20s for Wednesday. Very cold
conditions are likely Wednesday night and Thursday morning if we
have sufficient clearing. Raw model data supports lows in the lower
teens, but single digit lows would be more likely if we have
snowpack and clear skies. Highs Thursday will modify slightly with
low-mid 30s expected, though these might still be too generous if
a light snowpack remains.
.AVIATION (00Z TAF Update)...
Updated at 550 PM EST Thu Feb 4 2016
Only outstanding question is when the VFR strato-cu ceiling will
clear out of LEX. Based on current trends expect that to be an hour
or two after the valid TAF time. BWG and SDF have already cleared,
but will initialize with a light NW breeze, then go light/variable
by late evening as high pressure settles over the Ohio Valley. Clear
skies will continue for the remainder of the period, with light SW
flow developing late Fri morning once the ridge axis pushes to our