Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 271726
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
1226 PM EST Thu Nov 27 2014
...Updated Aviation Discussion...
Issued at 935 AM EST Thu Nov 27 2014
Deep NW flow has developed behind exiting Clipper system, leaving us
with a cloudy and somewhat raw day. Near-term guidance suggests
temps won`t rise much, but given upstream breaks in the stratus we
could rise a few degrees if there is well-timed sunshine. Max temps
should lean lower than guidance but only slightly...as mid/upper 30s
look to be on the generous side but still attainable. Updates on the
way to clean up morning snow mentions, as the rest of the day will
.SHORT TERM (Now through Friday)...
Issued at 305 AM EST Thu Nov 27 2014
In the near term, compact clipper system continues to slide eastward
across Kentucky this morning. Most of the precipitation with this
system is now falling in the form of snow as the thermal profile has
cooled sufficiently. Surface temperatures have remained at or above
freezing which has limited accumulations. Area webcams have shown a
dusting to a light coating on mainly grass and elevated surfaces.
For the remainder of the overnight hours, we expect this band of
snow to continue to pivot off to the east. The heaviest snow will
generally be confined to areas along and just south of Interstate 64
with areas generally from Elizabethtown to Liberty, Kentucky having
the best chances of seeing light snowfall accumulations. In
general, it still appears that a light slushy accumulation on grassy
and elevated surfaces will be the most we`ll see with this
activity. Surface temperatures are expected to bottom out around
32-33 degrees for the remainder of the overnight period. Some
locations across southern Indiana my drop to around 31 by daybreak.
For today/tonight, the multi-model consensus continues to be in
agreement with the clipper system moving off to the east. However,
low-level moisture will remain in place across the region to keep
abundant cloudiness around for much of the day. Afternoon
temperatures look to warm into the 35-37 degree range across the
north with 36-40 degree ranges across the south. This is a little
cooler than the previous forecast. Cloudiness will likely linger a
bit into the evening and overnight hours. With the thermal profile
cooling at all levels, probably will squeeze out a few snow flurries
here and there. Best chances of this would probably be in our
eastern sections closer to the higher moisture. Lows tonight will
be chilly with lows dropping into the lower-middle 20s.
For Friday, we`ll see high pressure passing through the region. This
should result in generally partly cloudy skies. The high should
move off to the east during the afternoon hours allowing more of a
southerly flow to develop. This will allow temperatures to moderate
a bit with highs in the lower 40s in the north with lower-middle 40s
across the south.
.LONG TERM (Friday Night through Wednesday)...
Issued at 255 AM EST Thu Nov 27 2014
Milder conditions are in store for the region this weekend as
temperatures are expected to rise above normal by Sunday. Through
the weekend we will be sandwiched between high pressure to the east
and a low pressure system moving out of the upper Midwest and into
eastern Canada. This low pressure system will eventually swing a
cold front through the lower Ohio Valley Sunday night into Monday.
Ahead of this front southerly to southwesterly winds will advect in
warmer and moister air this weekend. Isolated to scattered showers
are expected Saturday through Sunday with the better chance for
showers across southern IN and central KY. High temperatures will
warm from the low to mid 50s on Saturday to the low to mid 60s on
Sunday. Lows will be in the upper 40s to low 50s Sunday.
The better chance for rain will come on Sunday night into Monday.
Models are actually in less agreement tonight than last night with
the timing of the front. The newest ECMWF came in much slower with
the front and highest precipitation chances. Will go somewhere in
the middle between it and the GFS for now with 40-50% chances for
precip both Sunday night and Monday. Rain chances will continue into
Monday night, particularly lingering across the Lake Cumberland
region. Despite temps falling into the 30s overnight, think this
precip will be all rain as a pronounced warm layer aloft can be seen
Forecast confidence is lower for Tuesday and Wednesday as model
solutions diverge. A weak disturbance looks to move up from the
southwest Tuesday bringing another round of light showers with a
weak front possibly moving through Tuesday night. Wednesday does
look to be drier, though this will be dependent on high pressure
building in. Temps will drop back down below normal Tuesday but may
rebound to near normal by Wednesday.
.AVIATION (18Z TAF Update)...
Updated at 1220 PM EST Thu Nov 27 2014
Deep and cyclonically curved NW flow has developed over the Ohio
Valley in the wake of the overnight Clipper. Low cloud deck has hung
in all morning, with persistent MVFR ceilings that have just barely
managed to lift above fuel-alternate thresholds. Expect status quo
through most of the afternoon with high-end MVFR and NW winds around
After sunset look for winds to diminish and ceilings to scatter out.
Another impulse will swing through overnight, but impact will be
minimal as it will only bring in a mid-level ceiling. Light south
winds and VFR conditions expected on Fri.