Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 271756

Area Forecast Discussion
National Weather Service Louisville KY
156 PM EDT Thu Apr 27 2017

...Updated Aviation Discussion...

.Short Term...(This evening through Friday night)
Issued at 230 AM EDT Thu Apr 27 2017

...Breezy this Morning...


Early this morning, a sfc low over central IL was slowly moving NNE
as it gradually becomes more wrapped up within the upper low over
the north central U.S. and southern Canada. This low pressure system
will push a cold front eastward through our region this morning and
with it will come gusty winds and showers w/embedded t-storms.  A
low level jet of 50-60 kts @ 850mb will be present during the early
morning hours.  The environment will become mixy during the pre-dawn
hours resulting in wind gusts of 30-40 mph inside and outside of
convection.  Although convection will generally be on the decline
with mainly rain showers and a few rumbles of thunder early this
morning, stronger wind gusts may mix down in even showery activity.

The cold front is progged to move through the area by mid to late
morning with precipitation coming to an end shortly after the
frontal passage by late morning or early afternoon in most areas.
Expect mostly cloudy conditions for the remainder of the day with
highs dropping back into the mid 60s to low 70s.


Brief sfc high pressure will pass through the region tonight
resulting in partly cloudy and dry conditions. Low temps should
range from the upper 40s to lower 50s.


Friday a warm front extending northeast from a developing low
pressure system over the south central U.S. will sharpen somewhere
over the Ohio Valley.  Exact placement of this front will be
critical in resulting convection which may start late in the day Fri
but mainly occur Fri night. Isld to sct showers/storms could
materialize as early as Fri late afternoon/evening bringing a threat
for severe weather.  However, a strong cap over the region Fri
should limit convective activity until a strong LLJ gets going Fri
night enhancing convergence and isentropic lift for more numerous
organized storms.  See more about severe wx potential for Fri night
in the long term discussion.


.Long Term...(Saturday through Thursday)
Issued at 355 AM EDT Thu Apr 27 2017

...Severe Weather Potential Increasing for the Weekend...

Friday Night - Early Saturday Morning...

A sharpening warm front looks to settle somewhere over the Ohio
Valley Fri.  Exact placement of this front will be critical for
precip chances and potential severe wx Fri night.  While a strong
cap will remain place for much of the day time hours Fri, a strong
LLJ will cause convergence and isentropic lift Fri night which will
likely break the cap and cause showers/storms.  Some of these storms
could become strong to severe Fri night.  Wind shear profiles will
be supportive of organized discrete cells.  An abundance of CAPE is
expected to build along and south of the warm front Fri in the warm
sector.  These factors will combine to pose a damaging wind and
large hail threat Fri night into early Sat morning.  An isolated
tornado is possible as well especially in any sfc based convection
near the warm front.  Also with precipitable water values of 1.5-1.7
inches running well above average this weekend, flash flooding may
become a concern in areas that receive repeated storms.  Low temps
will remain in the 60s.

Saturday - Sunday...

The warm front is expected to lift north of the area during the day
on Sat leaving us in a strongly capped warm sector.  At this point,
the cap should be strong enough to prevent much more than isld-sct
convection Sat - Sun morning.  However, if the cap is able to be
broken by a subtle wave, a convective boundary or the warm front
sagging south, then we would again stand a chance at strong to
severe storms in a moderately unstable environment.

Sat high temps look to top out in the low to mid 80s with lows in
the upper 60s to around 70 Sat night.

Sunday the low pressure system will lift NE over the central U.S.
pushing a cold front east toward the Ohio Valley.  Some convection
may initiate Sun afternoon just ahead of a solid line of
showers/storms associated with the front.  The main line of storms
looks to pass through our area Sun night.  Storms on Sun/Sun night
will once again have severe potential with plenty of CAPE and strong
wind profiles. Storms will mainly pose a damaging wind and large
hail threat.  Again flash flooding may become a concern in areas
that receive repeated storms.

Highs Sun look to reach the low to mid 80s.

Monday - Wednesday...

Cooler and dry weather looks to arrive by Mon.  Temps look to remain
near normal for the first half of next week.  An active weather
pattern will continue, however, as rain chances arrive again by Tues
night and continue on and off through at least Thu.


.Aviation...(18Z TAF Issuance)
Issued at 155 PM EDT Thu Apr 27 2017

A cold front will continue to move its way through eastern Kentucky
taking the rain chances for central Kentucky with it. As a high
pressure system moves in, winds will remain gusty through the
afternoon hours before calming during the evening. Currently, BWG,
LEX, and SDF are in MVFR conditions due to low ceilings that are
expected to move away from the sites around 00Z. Tonight winds will
become light and variable. If cloud cover lifts tonight fog could
form around the forecast sites. Confidence is low that fog will be
an form. Otherwise, VFR conditions are expected during the overnight
hours through the rest of the forecast period.




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