Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 260654
Area Forecast Discussion
National Weather Service Louisville KY
254 AM EDT MON SEP 26 2016
.SHORT TERM (Now through Tuesday)...
Issued at 253 AM EDT Mon Sep 26 2016
With the new week comes a new weather regime...one more suitable for
this time of year.
A cold front will cross the region from west to east this morning,
exiting our Blue Grass counties around lunchtime. Trailing the
surface front will be the corresponding 5H trof axis and vorticity
ribbon which will sweep out the last of the showers this afternoon.
A band of showers is expected, especially along and north of the I-
64 corridor. A few elevated rumbles of thunder can`t be ruled out
but MUCAPE looks weak and soundings show very little instability.
Rainfall amounts will be in the neighborhood of a quarter inch or
High pressure nosing in behind the departing front will bring dry
and pleasant weather tonight and Tuesday.
Highs will be in the 70s today and tomorrow with lows tonight mostly
in the 45 to 50 degree range...a little warmer in urban cores.
.LONG TERM (Tuesday Night through Sunday)...
Issued at 244 AM EDT Mon Sep 26 2016
The long term will be dominated by a closed upper low, beginning
over the Great Lakes at the start of the period. By Wednesday
evening it will sink into the upper Ohio Valley and then proceed
into the central Appalachians Thursday. At this point the future of
the low becomes more murky. After wandering around the region for
the end of the work week, the GFS and GEM kick it out this weekend
while the ECMWF keeps it generally over the OV. The EC seems to have
been performing slightly better with this feature recently, with
other models eventually catching up to the EC`s solutions. When a
cut-off ejects is particularly difficult to predict, so confidence
in the outer periods of the forecast is especially low.
Nevertheless, the preferred solution right now is that some degree
of upper troffing will remain overhead through this weekend.
Cold temperatures aloft associated with the low/trof will lead to
steep low/mid level lapse rates. Atmospheric cross sections indicate
sufficient moisture to support widely scattered largely diurnal
(afternoon/evening) light rain showers. The forecast will have
several mentions of rain as a result, but it`s not going to be a
wash-out. Actually, given the pleasant temperatures, the weather
this week should be pretty nice outside of the splash-and-dash
High temperatures each day should generally be in the 70s, though
some folks may not get out of the 60s Thursday. Lows will mostly be
a few degrees either side of 50.
.AVIATION (06Z TAF Update)...
Issued at 1245 AM EDT Mon Sep 26 2016
The main focus in this TAF period is the frontal passage slated for
this morning between 12-18z across central Kentucky. As of 5z, the
front is analyzed from northwest Indiana to southern Illinois.
Regional radar shows scattered showers developing across central IN
southwest into southern IL.
Expect the front to sweep through SDF between 12-15z, BWG between 14-
17z and LEX between 15-18z. Low-top showers with some thunder will
accompany the front. Ceilings are expected to be mainly VFR, at
least initially though some MVFR ceilings are possible in any
stronger shower for brief periods. Northwest winds will bring drier
air during the afternoon and help scour out cloud cover by late
afternoon. By 00z, central Kentucky should be clear with westerly
winds 5-7 kts. Drier air and a well mixed boundary layer should be
enough to prevent fog formation tonight.