Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 141813

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

...Updated Aviation Discussion...

.Forecast Update...
Issued at 1145 AM EDT Sat Oct 14 2017

Low stratus is still persisting across portions of the Lake
Cumberland plateau this morning and is not showing any signs of
dissipation. Surface analysis/obs reveal an impressive 10-15 degree
dewpoint moisture gradient between northern and southern Kentucky,
with the stratus riding along and behind the surge of low level
moisture. Some short-term high-res models indicate the stratus will
persist through the early afternoon across the Lake Cumberland
plateau and Bluegrass region before slowly eroding away. Forecast
sky cover has been updated to reflect this.


.Short Term...(Today through Sunday)
Issued at 300 AM EDT Fri Oct 14 2017

Things are quiet across the CWA at this hour, and the only real
concern is for some fog. Seeing some fog on satellite imagery, and
it`s mainly confined to the river valleys at this point. Do think
the main limiting factor is that near-surface winds are up a bit
more tonight around 10-15 knots, and keeping things just mixy enough
for fog to be much of a problem. Will still mention fog in the
products, mainly in the river valleys.

Otherwise, expect the warmest day of the forecast period with highs
topping out in the low 80s. We`ll see plenty of sun.

Tonight will be quiet as well, however we`ll notice an uptick in the
southerly flow along with increasing sky cover toward dawn. This
will result in much milder lows in the mid and upper 60s. The rain
should hold off until just after daybreak in our western counties.

As we move into the day on Sunday, a surface low over the Great
Lakes will drag a cold front into our area. Expect numerous showers
with the potential for a few rumbles of thunder through the day as
the system moves from west to east. Do think we could see some gusty
winds around 25 mph at times either inside or outside of showers.
Gradient winds ahead of the front, and then steepening low level
lapse rates behind the front could both contribute. Overall, not
expecting a lot of rain with most spots a tenth of an inch or less,
but coverage should be pretty high. Will note that the low level jet
does get into the 40-45 knot range over southern IN as it responds
to a 120+ knot upper jet, so can`t totally rule out a gusty shower
or brief t-storm in that area. However, the overall severe threat is
very low.

.Long Term...(Sunday night through Friday)
Issued at 300 AM EDT Sat Oct 14 2017

Sunday Night - Monday Night...

Surface high pressure will build into the area behind the cold front
Sunday night. Meanwhile, the upper trough axis will pass through
Monday. This will be a dry and much cooler stretch of weather as
Sunday night lows drop into the low and mid 40s. After Monday highs
only reach into the low 60s, Monday night will see the coldest temps
of the forecast period. Look for upper 30s and low 40s in most
spots, with a few patches of frost possible in some of the sheltered

Tuesday - Friday...

The upper pattern will flip from NW flow, to zonal, and then weak
upper ridging by the end of the week. Meanwhile, high pressure will
remain firmly in control at the surface. This will be an extended
stretch of dry weather with temperatures back to the low to mid 70s
Wednesday through Friday. These temps will be a couple degrees above
normal, especially by Thursday and Friday. After another chilly
morning with lows in the upper 30s and low 40s on Wednesday,
Thursday/Friday morning lows will be back toward the upper 40 and
low 50s.


.Aviation...(18Z TAF Issuance)
Issued at 200 PM EDT Sat Oct 14 2017

A SCT/BKN MVFR deck continues to push northeast across southern and
eastern KY. The northern extent of these clouds currently runs from
BWG to LEX. BWG had a couple hours with a BKN MVFR deck earlier this
morning, but these clouds shouldn`t result in meaningful aviation
impacts. Prevailing VFR conditions are likely this afternoon through
the overnight period.

SSW winds have increased this afternoon as low pressure deepens over
the Plains. This low pressure system will continue to strengthen as
it tracks northeast through Wisconsin tonight. By 03-06z tonight, a
low level jet of 40-45 kts is expected to develop within 1500-2000
ft above ground out of the southwest. However, LLWS is marginal
since stronger surface flow will be in place as well. Expect a
15-20 degree wind shift between the surface and 2 kft. The strong
SW LLJ will continue through mid-morning Sunday.

After 12z Sunday, expect surface winds to increase further to 10-15
kts with gusts to 20-25 kts. The surface cold front will push
through all four TAF sites during the morning and early afternoon
hours. Expect prevailing light to moderate showery weather with
perhaps a rumble of thunder with the frontal passage.




Short Term...BJS
Long Term...BJS
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