Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 210712
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
312 AM EDT Tue Oct 21 2014
.SHORT TERM (Now through Wednesday)...
Issued at 305 AM EDT Tue Oct 21 2014
Cold front is progressing slowly through the Ohio Valley overnight,
with surface winds still out of the WSW over nearly the entire state
of Kentucky. Decent strato-cu shield is evident over the northern
half of Indiana and much of Ohio as the low levels are modified by
As the day progresses, the front will push SE across the region, and
deep NNW flow will develop. Most of the column will be quite dry,
but the fetch off of Lake Michigan will draw a shallow ribbon of
moisture into southeastern Indiana and the Bluegrass region of
Kentucky. Will include a brief window late this morning for a
shallow light shower or two to develop, but both coverage and QPF
will be minimal. Clouds and cold advection will really hold temps
back, and we can expect a decent range from NE to SW. Most of the
Bluegrass region will struggle to crack 60, while south central KY
will be up to 10 degrees warmer.
Expect clearing skies tonight and plenty of sunshine on Wednesday as
the surface ridge builds from the NW while the upper ridge builds
from the SW. Light north winds overnight will keep temps from
bottoming out, so will favor the slightly milder NAM MOS for lows
tonight. Wednesday will run even cooler with the shallow cold air
mass tightening its hold, with upper 50s across the board.
.LONG TERM (Wednesday Night through Monday)...
Issued at 255 AM EDT Tue Oct 21 2014
In contrast to the last few days of multiple frontal passages, the
long term pattern will settle down, with little if any rain chances
and temperatures starting off near normal then steadily rising. The
GFS does have a weak front passing us Thursday night and Friday. As
with the last few systems, models fade precip chances away before
getting here, but wonder if we will be able to squeeze out a
hundredth of an inch in a few spots. The latest SREF hints at this
chances, and will trend up just a little in pops, but stay under 20
percent. That front will slow the rise in temps for one day, but
Saturday and Sunday ridging will build into the region. On Monday
southerly winds will pick up ahead of a cold front across the
Central Plains. This front will hold off getting in here until just
beyond this forecast period.
The only other thing to mention in this forecast is the chance for
frost Thursday morning. Most of the model guidance places the center
of a surface high near our region by daybreak. Forecast lows should
be in the 30s areawide, with our Bluegrass counties at least
dropping into the mid 30s. Thus expect at least areas of frost there
with patchy frost farther west. Would not be surprised to see the
next couple of forecasts come in a little cooler, with a frost
advisory possible for portions of our forecast area.
.AVIATION (06Z TAF Update)...
Updated at 115 AM EDT Tue Oct 21 2014
Weak cold front is slow to progress past the Ohio River, but will
gradually push south across Kentucky overnight. Light SW winds will
veer to NW or even N by daybreak. Main source of uncertainty is how
far south the strato-cu deck over Indiana and Ohio can build. At
this point expect it to build into SDF and LEX, but BWG will remain
mostly clear. Kept the ceilings VFR, but just barely so at LEX. Even
if LEX does go MVFR expect it to stay above fuel-alternate
High pressure builds from the north during the daytime on Tuesday,
but without a strong push will keep wind speeds just under 10 kt.
VFR strato-cu ceiling will persist at SDF and LEX, but could scatter
out later in the afternoon. Light north winds and clearing skies
expected in the evening.