Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 181704
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
104 PM EDT Thu Sep 18 2014
...Updated Aviation Discussion...
.SHORT TERM (Now through Friday)...
Issued at 300 AM EDT Thu Sep 18 2014
In the near term, a scattered to broken deck of mid-level cloudiness
will continue to stream eastward across the forecast area. These
clouds will keep the threat of widespread fog development down but
also result in slightly warmer overnight minimum temperatures. A
gradient of temperature was noted across the area with the coolest
readings up in the Bluegrass region with the warmer readings down
across the southern part of the state. Temperatures ranged from the
lower 50s in the Bluegrass to around 60 in areas S/SW of Bowling
Green. We expect temperatures to fall a few more degrees and bottom
out in the lower-middle 50s. A few upper 40s can not be ruled out
in our typical cooler spots in the Bluegrass region.
For today and tonight, high pressure cell to the northwest will
gradually build into the region. This will result in partly to
mostly cloudy conditions early this morning to go more partly cloudy
by the afternoon hours. A light northeasterly wind will keep
temperatures cool once again. Verification statistics show that the
models have exhibited a warm bias over the last 5 days with max/min
temperatures. Therefore, have gone below guidance again and stuck
closer to the cooler weighted model mean. This results in highs in
the lower 70s across our northern sections with lower-middle 70s
across our central and southern sections. Mostly clear skies are
expected for the overnight period with lows in the upper 40s to the
lower 50s in the north and mainly lower 50s across the southern
For Friday, the northwesterly flow aloft will gradually become more
zonal and we expect to see more southerly surface level flow come
back into the region. Thus, slightly warmer temperatures are
expected. Have again gone on the lower edge of the guidance
envelope to account for the warm model biases of late. Highs Friday
will range from the mid-upper 70s in the north to around 80 along
the KY/TN border region.
.LONG TERM (Friday Night through Wednesday)...
Issued at 255 AM EDT Thu Sep 18 2014
The long term will begin with southerly flow and warmer temperatures
as high pressure over New England slowly shifts to the east.
Temperatures on Saturday morning will start out in the upper 50s to
lower 60s and rise into the lower to mid 80s by the afternoon. This
will be the warmest day of the long term.
An upper level trough and surface low will move across the
northeastern CONUS through the second half of the weekend and into
the early work week. This will drag a cold front through on Sunday
into Sunday night. Scattered showers and thunderstorms will
accompany the front as it moves through. There may be a few storms
pre-dawn Sunday in southern Indiana. Rain chances will increase
through the morning as the front moves through. The best chance
looks to be in the afternoon as temps warm and the region becomes
somewhat unstable. Rain should end by Monday morning with clouds
clearing out by mid day. Temperatures will fall through this period.
Highs on Sunday will be in the upper 70s to lower 80s while Monday`s
highs are expected to reach only in the lower to mid 70s. Lows will
fall from the 60s to the 50s.
High pressure will build in at the surface behind the front. Aloft
an upper level trough will be replaced by ridging by midweek.
Tuesday will remain cool with highs in the lower 70s (possibly 60s)
and lows in the upper 40s to lower 50s. We will then see a gradual
warming trend the next couple of days.
.AVIATION (18Z TAF Update)...
Issued at 1240 PM EDT Thu Sep 18 2014
Mid-level deck from earlier this morning continues to thin, but will
leave behind a scattered cu field for the remainder of the
afternoon. ENE winds will generally run around 6 kt, but better
mixing associated with the SDF heat island will keep speeds up
around 10 kt.
Winds will lay down this evening with the loss of heating, and cu
deck will dissipate as well. Low levels will remain just mixy enough
overnight to preclude significant fog formation, but will follow
guidance with a TEMPO for MVFR visibilities around daybreak in BWG.
Light east winds and scattered cu take over late Friday morning.