Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 131022
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
622 AM EDT Fri Oct 13 2017

...Updated Aviation Discussion...

.Short Term...(Today through Saturday)
Issued at 330 AM EDT Thu Oct 13 2017

Overnight satellite imagery shows low stratus continuing to mix out
from east to west.  In the wake of clearing, GOES-16 fog product
shows areas of fog developing across the region.  The fog, so far
has been limited to the deeper river valley regions of central and
eastern KY.  For the remainder of the overnight period, nocturnal
cooling will continue and areas of fog, some locally dense will
continue to develop.  Further west, low stratus deck may hold on
across our far northwestern areas.  Overnight lows look to cool into
the upper 40s in the east with readings bottoming out around 50 in
the western sections.

For today and tonight, we should mix out any lingering cloud cover
this morning with mostly sunny conditions expected for the late
morning and into the afternoon hours.  Highs this afternoon should
warm into the 70-75 degree range.  Clear skies are expected tonight
with lows cooling into the lower-mid 50s.

High pressure will continue to strongly influence our weather for
Saturday with mostly sunny conditions and slightly milder
temperatures.  Highs look to top out in the upper 70s east of I-65
with lower 80s mainly west of the I-65 corridor.

.Long Term...(Saturday night through Thursday)
Issued at 330 AM EDT Fri Oct 13 2017

Latest guidance continues to be in agreement with a strong upper
level trough axis swinging through the region on Sunday.  Associated
surface cold front will approach the region Saturday night with some
showers and thunderstorms ahead of it.  These storms look to
diminish overnight and then redevelop later Sunday afternoon as the
front pushes through the region.  With this forecast, will keep high
PoP chances going for Sunday and into Sunday night.  Speed of the
system is similar to the last runs, and faster than 24 hours ago. So
we should see more cold air advection Sunday night into Monday
morning.  It will be quite windy on Sunday with a rather large
pressure gradient over the region.  Southwest winds of 15-20 MPH
with gusts up to 30 MPH will be possible.  Winds will quickly shift
to the west and northwest and remain elevated into the afternoon and
evening before diminishing overnight.  Highs Sunday will likely
exhibit a gradient with upper 60s over our northwest sections to the
mid-upper 70s over the east and southeast sections.  Lows Sunday
night will likely cool into the 40-45 degree range.

A cold northwest flow will remain in place across the region for
Monday.  Probably will see a diurnal cu field develop.  Highs will
likely top out in the upper 50s to the lower 60s across the region.
Center of large Canadian high will be over us Monday night into
Tuesday morning which should provide our first decent cold night of
the fall season.  Widespread lows in the lower 40s are expected with
the typical colder spots dipping into the mid-upper 30s.  Patchy
frost will be possible in those colder locations and we`ll continue
to watch this over the next few days.

For Tuesday through Friday, the upper level flow will flatten out
and become zonal by mid week and then start to amplify a bit as we
close out the week.  With above normal heights in the eastern US and
a lower heights in the west, a dry and warming pattern is likely for
the Ohio Valley for much of next week.  We did lower our dewpoints
quite a bit through the period as we should see plenty of good
diurnal mixing each afternoon.  Wouldn`t be surprised to see
dewpoints mix out into the upper 30s to the lower 40s each
afternoon.  Daytime highs will start off in the upper 60s to around
70 on Tuesday and then warm into the 70-75 degree range for Wednesday
through Friday.  The model guidance may be a bit underdone toward
the later part of the week, especially if the upper flow amplifies a
little quicker and we get into more of a south/southwest flow faster.

Looking beyond into next weekend and into week 2-3, latest guidance
signaling another weather system coming through around the 21st to
22nd bringing another round of showers and storms to the region.
We`ll likely see a brief cool down behind that system, but the upper
pattern looks to re-amplify after that with another mild pattern
shaping up.

For the last two week or so, combination of organic techniques and
signal analysis methods have been strongly suggesting a pattern flip
as we close out the month of October. We`re now starting to see this
in the dynamical guidance as the persistent trough west/ridge east
pattern looks to break down and a major downturn in temps is a
growing concern as we head toward Halloween. While details are still
to be worked out, large scale pattern changes often result in highly
impactful weather, and there are strong signals suggesting that a
period of high impact weather will likely be seen across the Ohio
Valley later in the month.

&&

.Aviation...(12Z TAF Issuance)
Issued at 1022 AM EDT Fri Oct 13 2017

Dense fog has developed at BWG/LEX, meanwhile low stratus seems to
be wining the battle at HNB where near-surface winds are slightly
stronger. Early morning TAFs will reflect the latest observed
trends, with improvement expected a couple hours after sunrise. At
SDF, expect vis to drop right around the VFR/MVFR threshold, but
largely stay less restricted than the other sites.

After improvement a couple hours post-sunrise, expect light and
variable winds with a few-sct cumulus around 1500-2500 k feet.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&

$$

Short Term...MJ
Long Term....MJ
Aviation...BJS



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