Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 130724

Area Forecast Discussion
National Weather Service Louisville KY
324 AM EDT TUE OCT 13 2015

.SHORT TERM (Now through Wednesday)...
Issued at 300 AM EDT Tue Oct 13 2015

The synoptic pattern early this morning features an amplifying
trough across much of the east coast, with an upstream ridge over
the western CONUS.  This regime will persist through the short term
period, bringing temperatures just below seasonal normals and dry

The main forecast challenge will be fog/low stratus this morning.
The surface cold front has pushed well east of the region, but the
drier air has lagged the fropa by a few hours which has allowed
fog/low stratus to form.  Winds have stayed up across the
northeastern CWA manifesting much of the low-level moisture as
stratus, but winds have died down just enough over southern KY for
some dense fog formation there.  For now, have handled this with an
SPS as the expectation is that it will improve before sunrise.
However, we reserve the right to issue a Dense Fog Advisory for
portions of mainly southern KY if the fog continues to persist and
if it looks it may have more impact (affecting more of the morning

Otherwise, today will be a cooler but still pleasant fall day.
Sunshine will break out this morning, but another disturbance riding
through the northwest flow aloft may have enough moisture around
850mb to bring some stratus into the northeastern CWA (northern
Bluegrass) late this afternoon into the early evening.  Highs will
top out in the mid/upper 60s to lower 70s.

For tonight, mainly clear skies will prevail.  High pressure will
build into the central CONUS, but just enough of a gradient should
remain over the Ohio Valley to keep most locations` temps from
completely tanking. Lows in the upper 30s in the typically cooler
spots look likely, with low/mid 40s elsewhere.

Wednesday will be mostly sunny.  850mb temperatures will warm
slightly, thus think highs will top out a couple of degrees warmer
than today, with readings in the upper 60s/lower 70s expected.

.LONG TERM (Wednesday Night through Monday)...
Issued at 320 AM EDT Tue Oct 13 2015

...Frost Possible this Weekend...

A broad upper level trough will persist over the Midwest through the
long term period providing a period of mostly below normal temps for
the end of this week into the weekend.  A few cold fronts will drop
into the Ohio Valley ushering in colder air.

The first front will arrive Friday morning.  While confidence is
still low on if there will actually be enough moisture with this
front to produce precipitation, decided to go with a 20% POP based
on a blend of mid range models and coordination with neighbors. The
last two runs of the ECMWF and GFS ensembles are most optimistic
with moisture profiles and light rain shower chances.  Ahead of this
front, expect highs on Thurs to reach the mid 60s to lower 70s with
lows in the 40s and lower 50s Thurs/Fri mornings.  Fri morning will
be the warmer morning with clouds and potentially some showers in
the area. Highs on Friday in the post-frontal airmass will range
through the 60s.

The weekend looks dry although a secondary dry cold front will push
south through the region on Fri night/Sat.  This colder airmass will
put low temps in the 36-40 degree range Sat morning and 31-37 degree
range Sun morning.  We could see frost develop either morning
although Sun morning looks to have the most widespread frost with
high pressure overhead providing light winds and ideal rad cooling.
Some locations may even go below the freezing mark.  Stay tuned for
possible future frost/freeze headlines this weekend.  High temps
will be limited to the 50s both Sat/Sun.

We will enter a return flow for the beginning of next week helping
temps to moderate back closer to seasonal normals.


.AVIATION (06Z TAF Update)...
Issued at 104 AM EDT Tue Oct 13 2015

Main forecast concern will be fog/stratus beginning to plague sites
currently.  KLEX has already gone IFR in stratus and expect KBWG to
go IFR mainly in fog soon.  Will keep KSDF free of any restrictions,
but a brief IFR cig is not out of the question over the next couple
of hours.  Otherwise, drier air will advect into the region through
the night, so expect KBWG and KLEX to improve to VFR over the next
few hours, possibly more towards sunrise at KLEX.  Once conditions
return to VFR, the remainder of the day will feature westerly winds
possibly gusting to 20 knots at times, with sct/bkn VFR stratocu
developing mainly at KSDF and KLEX in the afternoon hours.


.LMK Watches/Warnings/Advisories...


Short Term........KJD
Long Term.........AMS
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