Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 091047

Area Forecast Discussion
National Weather Service Louisville KY
647 AM EDT FRI OCT 9 2015

...Updated Aviation Discussion...

.SHORT TERM (Now through Saturday)...
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 (Saturday Night through Thursday)...
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 (12Z TAF Update)...
Issued at 647 AM EDT Fri Oct 9 2015

A cold front will cross the region today, bringing a gradual wind
shift from southwest this morning to west midday and northwest by
late afternoon. Showers will develop and spread in from the west
late morning/mid day and proceed to the southeast across central
Kentucky this afternoon. Will account for this with VCSH in the SDF
TAF, and will go ahead and include VCTS/CB in the BWG and LEX TAFs.
The best chance for thunder at BWG/LEX will be during the early to
mid afternoon hours.

It looks as though ceilings will hang around through the night and
into Saturday morning behind the front. Will remain optimistic for
now and keep them just barely VFR, but they may indeed fall to high-
end MVFR levels.


.LMK Watches/Warnings/Advisories...


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