Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 111652
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
1152 AM EST Wed Dec 11 2013
...Updated Aviation Discussion...
Issued at 1100 AM EST Wed Dec 11 2013
Mostly clear skies were noted across the forecast area this morning
on the most recent visibility. Nice snow pack clearly seen on the
high-res visible this morning...generally north of the WK and BG
Parkways. Temperatures across the snow pack continue to run
slightly below our current forecast...so have adjusted those temps
down slightly. Still think we`ll see temperatures north of the
river top out in the middle to upper 20s. Middle 30s are likely
across northern Kentucky with upper 30s to the lower 40s down across
southern KY in the snowless areas.
Another cold front will push through the region this afternoon
resulting in colder air pushing back into the region this afternoon
and tonight. There is a good possibility that some of our northern
counties in our forecast area could see sub zero readings tonight
(like around the Paoli to Salem Indiana area).
.SHORT TERM (Now through Thursday)...
Issued at 325 AM EST Wed Dec 11 2013
To start the morning, freezing fog (dense in some spots) was
observed over areas with snowpack over southern Illinois/southeast
Missouri early this morning. Good low level moisture exists due to
slight melting of the snowpack yesterday which is becoming trapped
under an inversion as sfc high pressure is building into the Ohio
Valley. Thus, think that areas over south central Indiana that have
the best snowpack and experienced some melting today may have a
chance at developing patchy freezing fog this morning as well. The
one negating factor to fog this morning is winds which are running
10-15 kts just above the sfc helping to keep the atmosphere a bit
mixy. Still some of the short range high-res models develop fog
over south central Indiana and do think it`s possible so will
include with this forecast package. Will need to watch the areal
extend and density of any freezing fog that does develop this
morning, and update as necessary. Fog is not expected to become
dense at this time, however, any moisture in the air will readily
freeze on surfaces which are running well below the freezing mark
this morning. Thus, motorists should use caution and watch for
slick spots/black ice on roadways.
Any fog should dissipate quickly after sunrise this morning with
mostly sunny skies expected for the rest of the day. The main
forecast challenge will then be temperatures over the next few days
and whether or not we see a few flurries from a passing front this
Temperatures will be tricky due to snowpack over southern Indiana
and northern Kentucky. Have included a pretty good gradient in
temps today and tonight due to the snowpack. Highs look to reach
the upper 20s and lower 30s this afternoon in areas with snowpack
and warm into the mid 30s to lower 40s in areas without snowpack
over central KY.
An Arctic front will cross the area this evening ushering in very
cold temps. The front itself looks largely dry although a few of
the short range models are generating some flurries which could be
possible since the very cold, dense airmass will tend to squeeze out
any moisture in the atmosphere. However, will leave the forecast
dry for now and monitor light snow/flurries along the front today.
Tonight, temps turn very cold with single digits expected over areas
with snowpack over southern Indiana and lower 10s expected elsewhere
over central KY. With just a light NW wind, wind chills will easily
plummet into the 0 to -5 degree range over southern Indiana with
single digits expected over central KY Thurs morning. Any travelers
should bundle up Thurs morning!
Thursday looks to be mostly sunny as another sfc high pressure
controls the area with highs in the lower 20s to lower 30s across
.LONG TERM (Thursday night through Tuesday)...
Issued at 320 AM EST Wed Dec 11 2013
The long term will start off quite cold Friday morning with mostly
clear skies and high pressure just to the east of the region.
Temperatures will range from the teens in the northern half of the
forecast area to lower 20s across south central Kentucky. With
southerly winds, however, temperatures Friday will rebound back into
the upper 30s to lower 40s. Clouds will be on the increase through
the day as the next system begins to approach from the southwest.
The next chance for wintry precipitation will be Friday evening
through Sunday. A southern stream shortwave and associated surface
low near the Texas panhandle on Friday afternoon will track
northeast and cross the lower Ohio Valley through Saturday.
Precipitation ahead of this system will begin to move in Friday
afternoon to Friday evening. Friday night this looks to start off as
all rain or a mix of rain and snow across south central Kentucky.
Across north central KY and southern IN it may start out as all snow
or a mix of snow and ice pellets.
As warm air moves in aloft and at the surface Saturday, there will
be a transition to all rain by the afternoon. Temperatures on
Saturday will warm into the upper 30s to lower 40s once again. As
the system begins to move out Saturday night the rain will
transition back to snow. Some flurries or freezing drizzle may
continue in the Bluegrass region through Sunday morning before
moving out. Temperatures on Saturday night will fall back into the
20s, with temperatures holding steady or rising only a few degrees
A couple of clipper systems will then dive through the northwesterly
flow early next week. These are notoriously hard to time. At this
time it looks like far northern portions of the forecast area may
see a little snow Tuesday night. However, the timing/chance for any
precip from these systems will change as we get closer in time to
.AVIATION (18Z TAF Update)...
Updated at 1151 AM EST Wed Dec 11 2013
VFR conditions are expected through the upcoming TAF period.
Surface winds this afternoon will be out of the southwest this
afternoon in advance of an approaching cold front. Surface winds
are expected to be in the 8-11 knot range. Winds should veer to the
west late this afternoon and then shift to the northwest as the dry
front presses southward through the region. Frontal passage and
wind shift looks to occur between 11/23Z to 12/01Z at the
terminals. Northwest winds will continue overnight with speeds of