Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Louisville Kentucky
1202 am EST Mon Dec 29 2014
..updated aviation discussion...
issued at 920 PM EST sun Dec 29 2014
Current forecast remains on track this evening. Extensive cloud
cover remains over the region in the Post frontal airmass. Light
rain shower activity is now exiting the region and the remainder of
the night looks to be rather dry. Some lingering drizzle and fog
will be possible across our eastern sections this evening and into
the overnight period. Some partial clearing may take place towards
morning...especially in our northwest sections. This will allow for a
range of lows from the upper 20s in the west to the lower-mid 30s in
Short term (now through Monday night)...
issued at 230 PM EST sun Dec 28 2014
Some light rain continues across east central Kentucky this
afternoon in the wake of the cold front that went through this
morning. This light rain will continue to slowly shift eastward this
evening. The rain should be east of the forecast area by daybreak
tomorrow with dry conditions then expected through Monday night.
Cold air filtering in behind the front has left the region with
temperatures in the 30s this afternoon. Temperatures will remain
fairly steady for the remainder of the afternoon, then fall into the
upper 20s to mid 30s overnight.
Skies will remain cloudy overnight. Some clearing could start from
the north tomorrow afternoon into the overnight hours. Highs
tomorrow will be around normal for this time of year in the lower to
mid 40s. Lows tomorrow night will drop into the upper 20s to lower
Long term (tuesday through sunday)...
issued at 251 PM EST sun Dec 28 2014
An impressive dome of Canadian high pressure will be barging through
the Great Plains at the start of the long term period. Though it
will modify as it sinks southward, it will serve to keep US dry and
chilly through at least Thursday. The coldest night will be new
year's eve as the Mercury slips into the upper teens/lower 20s by
the time the sun rises on 2015. We won't be under the center of the
high so we will maintain a light breeze, resulting in wind chills
possibly as low as 10 degrees during the pre-dawn hours on the 1st.
GFS/ECMWF/Gem have come into remarkably decent agreement for the
system coming in from the southwest at the end of the week. A
surface low path to our west and north still looks likely. Not
surprisingly, the onset of precipitation has been delayed a bit, and
it may be further delayed in future runs. In the meantime, though,
we'll still have to stick with a chance of precip late Thursday
night into early Friday morning, especially west of I-65 and south
of the Ohio River. The cold air from the mid-week Canadian high
will be slow to scour out, so we could end up with a light wintry
By Friday afternoon all precipitation will be in the form of rain,
and should continue that way through Saturday (though Friday night
will have to be watched with regard to thermal profiles associated
with the placement of a possible warm front setting up in the
area). This will be a very wet system, with the Gulf wide open and
high pressure over the western Atlantic pumping moisture northward.
Precipitable water numbers may reach 1.3 inches, which would be in
the 99th percentile climatologically. The bulk of the wettest
weather is currently scheduled for Friday afternoon through Saturday
morning, with a few elevated rumbles of thunder even possible
Saturday morning. Precipitation totals for the entire system could
be in the one to two inch range.
Though the models dry US out Saturday night as the system pulls
away, for now will hold on to a small pop since the system will be
nearby and in case the timing of the system continues to slow.
Sunday another Canadian high will be nosing in from the northwest.
Aviation (06z taf update)...
issued at 1201 am EST Mon Dec 29 2014
Surface high pressure will slowly become more established over the
region through this forecast cycle, however will have to deal with
low clouds and mist through the overnight and into the day on
Monday. Conditions are expected to return to VFR as early as
tomorrow afternoon at sdf, but more likely in the evening hours at
In the meantime, expecting MVFR above fuel-alternate at sdf, with
bwg and Lex below fuel alternate. Bwg is currently IFR and don't see
much of a reason that ceilings will improve the remainder of the
overnight. Lowest confidence at Lex where obs are currently
reporting clear, however expect the lower ceilings to return
Winds are currently light out of the north and will only gradually
veer to a more north-northeast or NE direction tomorrow between 5 and 10 mph.