Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 302332
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
732 PM EDT Tue Sep 30 2014
...Updated Aviation Discussion...
.SHORT TERM (Now through Wednesday Night)...
Issued at 310 PM EDT Tue Sep 30 2014
A cool frontal boundary is sliding south into our CWA at this hour,
and will settle over the south central part of KY tonight. Solid
deck of stratocu that had been sinking south out of central IN this
morning has since dissipated, however has left a sizable temperature
gradient along the Ohio River Valley. Currently looking at upper 60s
across central IN to the low and mid 80s along the Ohio River and
southward. Southern KY has mixed out this afternoon with dew points
in the upper 40s in many spots, however higher dew points along the
frontal boundary will settle over the area tonight and could lead to
some fog concerns once again toward dawn. Have fog mentioned in the
forecast across south central KY, and will have to monitor through
the evening for more widespread coverage and magnitude.
Other than some stratocu development over the Bluegrass and a few
fog concerns across our south, a quiet evening is in store. Lows are
expected to dip mainly into the 50-55 range across central KY,
however upper 40s and low 50s are possible in southern IN.
Wednesday is going to be another nice day due to brief upper level
ridging and surface high pressure in control. Will get rid of some
morning low clouds and fog to yield mostly sunny skies and highs in
the low (NE) to mid 80s.
Upper level clouds ahead of the next system will stream into our
west late Wednesday night, otherwise another clear and quiet night
is in store with lows mainly in the 55 to 60 range. Low 50s in our
far NE Bluegrass counties.
.LONG TERM (Thursday through Tuesday)...
Issued at 305 PM EDT Tue Sep 30 2014
The long term period will feature a cool down to more seasonal temps
as well as a good chance for rain Thurs night/Friday morning.
A potent cold front will approach the area Thurs. We could see some
isld-sct showers/storms Thurs afternoon ahead of the main line of
convection associated with this front. Then a complex of numerous
showers and storms is expected to move through the region Thurs
night into Friday morning with perhaps the heaviest rains moving
through during the pre-dawn hours Friday morning through around
sunrise. Although no severe weather is expected with this system at
this time, PWATs will rise to 1.7 to 1.8 inches which is high for
this time of year resulting in periods of moderate to heavy rainfall
Thurs night/Friday morning. This may lead to some ponding of water
on roadways, but overall no major flood threat is anticipated since
this system looks to be a fairly quick mover and antecedent ground
conditions are dry. Temperatures ahead of this system will climb
solidly into the mid 80s for highs on Thurs. Friday will be cooler
with rains and lingering clouds in the lower 70s for highs.
The main cold air punch behind this cold front will arrive for Sat.
Models have trended colder in recent runs. Sat morning lows will
start out in the low to mid 40s with some upper 30s possible as
skies clear Fri night and the core of cold air sinks into the Ohio
Valley. Despite mostly sunny skies for Sat, high temps will likely
only reach the upper 50s and lower 60s with some of the raw model
guidance coming in colder than that. Lows Sat night into Sun
morning will again be quite chilly in the lower 40s with upper 30s
possible. Temps will moderate some for Sunday with highs reaching
the mid to upper 60s.
Another upper trough looks to dive into the Ohio Valley on Sun
night/Mon bringing shot of cold air as well as rainy conditions and
low clouds Sun night-Mon night. This second shot of cold air could
result in low temps falling into the mid to upper 30s Tues night
into Wed morning, however, confidence is quite low in the
temperature forecast that far out.
.AVIATION (00Z TAF Update)...
Issued at 730 PM EDT Tue Sep 30 2014
Fairly complicated aviation forecast for otherwise quiet weather.
Surface analysis has a narrow east/west plume of higher dewpoint air
just getting into the SDF/LEX corridor this hour and forecast to
sink slowly into south KY overnight. South KY mixed out well this
afternoon, with dewpoints dropping into the upper 40s. Normally the
latter would mean no chance for fog overnight, but with the
low-level moisture rolling in, it cannot be ruled out, possibly with
low stratus forming at all of the sites as well. Have trended the
forecast towards the possibility at all sites, but still only have
restrictions possible at KBWG and KLEX. Will have to update through
the night as we see what occurs.