Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 150131

Area Forecast Discussion
National Weather Service Louisville KY
931 PM EDT Sat Oct 14 2017

.Forecast Update...
Issued at 930 PM EDT Sat Oct 14 2017

Sprinkles/showers have dissipated over the area.  The current
forecast for the overnight period looks on track with temperatures
holding in the mid 60s to low 70s for lows ahead of an approaching
cold front.  Rain showers and perhaps a rumble of thunder will enter
the area from the NW close to sunrise.

Issued at 450 PM EDT Sat Oct 14 2017

Updated the forecast to include some sct sprinkles and isld showers
across south central KY through mid evening.  Strong moisture
advection combined with good instability have resulted in a few
light showers or sprinkles late this afternoon and expect those to
continue through sunset.


.Short Term...(This evening through Sunday night)
Issued at 247 PM EDT Sat Oct 14 2017

Current satellite/surface observations reveal a surge of low level
moisture across southern KY where dewpoints are currently in the
upper 60s to low 70s and a strato-cu field remains present. This is
all in response to a 1026mb high currently sitting over the
Carolinas while a 1004mb low sits over the central Plains, and flow
between the two systems is pulling in moisture from the Gulf of

A 45kt LLJ will develop overnight as a strong cold front approaches
from the west. While an inversion will develop, winds will still be
breezy at the surface, generally 10mph-15mph out of the southwest.
Overnight lows will be quite warm thanks to breezy winds and high
dewpoints, with areas west of I-65 staying near the 70 degree mark,
while east of I-65 lows will only fall into the mid and upper 60s.

A decaying line of convection will approach western portions of the
CWA by daybreak ahead of the cold front. Instability will be very
limited through the morning hours due to weak mid-level lapse rates
and cloud cover, so expect most of the precipitation to remain
lightning free. Additionally, QPF looks to be light at this time,
generally around or under a tenth of an inch. The cold front will
slice through the CWA during the day tomorrow, and temperatures will
fall considerably behind the front. For example, the 12z GFS has
temperatures at SDF tomorrow around the mid 70s at 11am, but falling
to the upper 50s by 5pm behind the cold front. Winds will be quite
gusty as well. Combination of strong CAA, pressure rises behind
front, and steep low level lapse rates will result in gusty 25mph-
30mph northwest winds tomorrow morning and afternoon.

Strong CAA will continue into tomorrow night as temperatures
continue to fall. Pressure gradient over region will begin to relax
after midnight, so should see winds lighten up a bit. Overnight lows
will generally be in the low to mid 40s.

.Long Term...(Monday through Saturday)
Issued at 258 PM EDT Sat Oct 14 2017

Surface high pressure will continue to build into the area behind
the cold front Monday with dry NW flow aloft. Monday will be the
coolest day of the week as the bulk of the cold air settles over the
region. Surface high will nearly be on top of the area Monday night,
and with light winds and clear skies, temperatures should bottom out
into the upper 30s to low 40s. A few of the sheltered, colder spots
in the CWA may even see some patchy frost by Tuesday morning.

Flow aloft will then transition into a quasi-zonal to upper ridging
pattern for the mid to late week period. This will result in a
gradual warming trend, and with no significant shortwaves embedded
within the flow, we should remain dry through this period.


.Aviation...(00Z TAF Issuance)
Issued at 740 PM EDT Sat Oct 14 2017

A cold front will move through the region tomorrow bringing rain
showers, MVFR cigs, and gusty winds.  VFR conditions will prevail
for tonight with increasing upper level clouds ahead of the front.
Rain showers and MVFR cigs will enter the region ahead of the front
between 12-16Z from west to east tomorrow morning. SW winds will
increase ahead of the front by mid morning with gusts in the 17-22
kt range. The fropa should occur between 17-21Z across the TAF sites
with rain showers continuing and gusty winds shifting to the WNW
behind the front.  There is a small chance for a rumble of thunder
from mid morning through mid afternoon tomorrow but feel chances are
too low to include in the TAFs attm.  Rains should end tomorrow
evening with conditions returning to VFR near the end of the TAF




Short Term...DM
Long Term...DM
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