Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 091754

Area Forecast Discussion
National Weather Service Louisville KY
154 PM EDT FRI OCT 9 2015

...Updated Aviation Discussion...

...Forecast Update...
Issued at 1205 PM EDT Fri Oct 9 2015

Updated the forecast to adjust POPs with greater POPs near and just
south of the Ohio River for the next few hrs.  A few storms have
already popped up this morning with wind signatures of 30-35mph on
radar.  Since these storms are a little better than originally
expected, feel that central and southern portions of KY will likely
see scattered to numerous storms this afternoon and a few may be on
the strong side with strong winds being the main threat. The cold
front causing these storms has made it to southern/central portions
of Indiana and should continue to provide forcing for convection
along and south of the front through this evening.  Areas north of
the front will enter more of a showery regime.

Issued at 900 AM EDT Fri Oct 9 2015

Updated the forecast to increase POPs over central KY from mid
morning through early afternoon.  The latest HRRR has a good handle
on precip development over central KY this morning, and it really
develops better coverage of showers with embedded isld-sct t-storms
over central/southern portions of KY late this morning through the
afternoon hours.  This seems to match the projected frontal timing
well.  So overall, doesn`t look like southern Indiana will see as
much precip as central KY today.  Also, because central KY precip
has started a bit earlier than expected, did follow the latest
CONShort guidance with slightly cooler high temps for today.  Highs
should range from 72-79.

.SHORT TERM (Now through Sunday)...
Issued at 308 AM EDT Fri Oct 9 2015

A cold front stretched from the Great Lakes through the mid-
Mississippi Valley to the Ozarks early this morning will steadily
push across southern Indiana and central Kentucky over the course of
the day today. As the atmosphere slowly destabilizes and upper
energy over the mid-Missouri Valley this morning crosses central
Kentucky this afternoon, convection will break out. Showers are
first expected to develop along and either side of the Ohio River by
late morning. As we head into the afternoon the showers will push
southeast and increase in coverage, with precipitable water values
pooling well above normal around 1.3 to 1.5 inches ahead of the
front. By mid and late afternoon thunderstorms will be possible,
especially southeast of a Bowling Green-Lexington line where lifted
index values should drop to around -5C.

0-6km bulk shear values still look to be on the order of 30-35kt
this afternoon with mid-level winds of 35-40kt. Soundings look
fairly well saturated and forecast DCAPE is very low. Gusty winds
with the heavier downpours will certainly be possible, but
widespread severe weather is not expected.

Given the over achievement of temperatures yesterday, will go with
the high side of guidance today, especially in areas that spend the
most time ahead of the front and convection this afternoon. This
results in MaxT ranging from lo-mid 70s in southern Indiana to lower
80s in southern Kentucky.

Showers will move off to the southeast this evening, with clouds
lingering through the night. Low temperatures will range from upper
40s to middle 50s on 5-10mph north breezes.

Clouds will continue to linger into Saturday morning but by
afternoon most locations should be seeing fair skies as high
pressure invades the Ohio Valley. Temperatures should top out from
the middle 60s to around 70...depending a lot on just how quickly
the clouds scour out.

.LONG TERM (Sunday night through Friday)...
Issued at 255 AM EDT Fri Oct 9 2015

The upper pattern will feature ridging over the SW CONUS and a
shallow trough across the NE for much of the long term. The Ohio
River Valley will lie in the stronger NW flow between the two
features, with a shortwave passing through Monday/Monday night. This
upper feature and its associated cold front will bring the only
chances for rain in the long term.

Saturday Night - Sunday Night...

Cutoff low will anchor of the Carolina coast to end the weekend.
Meanwhile brief upper ridging and surface high pressure will hold
influence. This will lead to mostly clear and dry conditions with
cooler temps behind the front. Lows wil be in the 40s on Saturday
night under good raditional cooling conditions. A few of our cool
valleys will likely drop into the lower 40s. Highs will be back in
the 70s on Sunday as steady SW surface flow returns.
Look for milder lows Sunday night in the upper 40s and low 50s.

Monday - Monday Night...

A shortwave and associated surface cold front pass through to start
the new week, bringing chances for rain showers. Models agree pretty
well on timing with the bulk of activity expected Monday afternoon
through Monday evening. However, there continues to be some
disagreement with the amount of moisture available. 09/00z ECMWF
continues to show a more amplified upper pattern which is able to
draw deeper moisture into the area, with GFS a little less robust.
Continued to compromise between the two which will warrant iso to
widely scattered rain showers mainly across our N and NE CWA.
Went with a blend of raw temps during this advective timeframe,
which will yield most highs in the mid 70s on Monday and lows in the
low 50s Monday night.

Tuesday - Thursday...

Shortwave trough axis and cold front pass east by Tuesday, with a
return to dry NW flow aloft and surface high pressure. Expect a dry
mid week. Temps will initially cool off behind the front on Tuesday
with highs only in the 60s. Tuesday night lows will be in the 40s.
We`ll return to the 70s Wednesday/Thursday with Wednesday night lows
in the lower 50s.


.AVIATION (18Z TAF Update)...
Issued at 135 PM EDT Fri Oct 9 2015

Convection will continue over the TAF sites through this evening
courtesy of a cold front moving through the region.

SDF...looks to be done with t-storm chances as the front is very
close shifting winds to the WNW.  Expect showery activity to
continue through this evening with VFR conditions declining to MVFR
from roughly 21Z-3Z.  Cigs should lift as dry air moves in at the
sfc allowing conditions to return to VFR by 3Z.

BWG/LEX...Should still see t-storm chances through the afternoon and
early evening hrs ahead of the front.  By 21-22Z, the front should
be through these TAF sites resulting in only showery activity
through the evening hours.  BWG looks to remain a bit close to the
upper level trough associated with this system which may cause them
to hold on to MVFR cigs and showery conditions through the overnight
hrs.  LEX should hover near MVFR/VFR threshold overnight and have
kept the TAF optimistic for now.  Both sites should go VFR by 13-16Z

Winds will veer at all TAF sites from WNW this afternoon to N
tonight to NE for tomorrow.  Wind speeds of 5-9 kts will be common
with higher gusts in t-storms.


.LMK Watches/Warnings/Advisories...


Short Term.....13
Long Term......BJS
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