Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 261654
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
1154 AM EST Fri Dec 26 2014
...Updated Aviation Discussion...
.SHORT TERM (Now through Saturday)...
Issued at 300 AM EST Fri Dec 26 2014
Still have a few sites showing some fog around Lake Cumberland, but
no automated weather stations are showing anything less than 7 miles
for visibilities. Satellite fog product only hints at the Lake
Cumberland fog, with more sites in Eastern KY. Will continue to
Will see a nice warmup today, after some morning lows right around
freezing, highs should get into the 50s for most locations under
mostly sunny skies. Will see high clouds filter in from the
southwest as the next system approaches. Continued southerly winds
today will bring in more moisture. Rain chances will return during
the day Saturday, as a cold front approaches. By afternoon, rain is
likely west of the I-65 corridor.
.LONG TERM (Saturday Night through Thursday)...
Issued at 322 AM EST Fri Dec 26 2014
Saturday Night - Sunday Night...
The Ohio Valley will be situated in SW flow through a deep layer
Saturday night, between western CONUS trough and upper ridge off the
Atlantic coast. Meanwhile, a surface low will move east out of the
Great Lakes, with its trailing cold front sliding through our region
Saturday night. Light rain is expected to be ongoing Saturday
evening, with the best coverage transitioning east of the I-65
corridor is coincidence with the best moisture transport and
isentropic lift. Deep moisture will be harder to come by after
midnight west of I-65 so will taper precipitation chances
dramatically to the NW toward dawn on Sunday.
Was prepared to continue trending the forecast drier east of I-65
for Sunday and Sunday evening, however have seen a trend with the
ECMWF back toward what the GEM has been consistently forecasting now
for a few days. This scenario would feature southern energy ejecting
out of the western CONUS trough and a stronger surface reflection
riding along the nearly stalled boundary to our east. This stronger
setup brings the precipitation shield further back to the NW
underneath the right entrance region of an upper level jet where mid
level deformation/frontogenesis would be present. If the trend
continues back NW much more, we could find deep enough moisture into
the cold air for a wintry mix to be possible Sunday evening. Not
ready to mention this (again) until split model camps come into
better agreement so will continue to mention chances of rain along
and east of I-65, with rain likely along the I-75 corridor Sunday
into Sunday evening.
Temperatures will be mild along and ahead of the front Saturday
night and Sunday, with a very small diurnal range. Look for lows
mostly in the 40s Saturday night, with upper 30s over southern
Indiana. Sunday will feature highs in the 40s. The cold air will
lag, however it will arrive by Sunday night with temperatures
falling into the 30s. Again, at this point it looks like the deeper
moisture outruns the cold air, keeping wintry precipitaton chances
very limited. Will continue to watch model trends to get a better
handle on Sunday evening.
Monday - Thursday...
Zonal flow aloft will dominate most of next week, with an arctic
high pressure building into the heart of the country. This will
result in dry conditions, although temperatures falling below normal
through the mid week time period. Highs in the upper 30s and low 40s
on Tuesday will give way to highs peaking in the low 30s on
Wednesday. Meanwhile, Monday night lows in the mid and upper 20s
will give way to Tuesday night lows in the 20 to 25 range, and lows
in the teens across much of the area on Wednesday night.
.AVIATION (18Z TAF Update)...
Issued at 1154 AM EST Fri Dec 26 2014
High pressure over the Carolinas will provide us with pleasant
weather for much of this TAF period. Flying conditions will be VFR
with southerly breezes of 5-10 knots through tonight.
On Saturday a weakening cold front will approach from the west,
spreading clouds and light rain into central Kentucky by afternoon.
Will keep conditions low-end VFR for now, though there are some
indications that ceilings may go MVFR by late afternoon.