Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 051658
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1258 PM EDT THU MAY 5 2016

...Updated Aviation Discussion...

...Forecast Update...
Issued at 830 AM EDT Thu May 5 2016

Updated the forecast to adjust POPs so that the timing of POPs
leaving central KY to the ESE is a little slower.  Did this based on
morning radar trends and newest high-res model guidance.  Still
nothing more than isld-sct showery activity with another wave
arriving from the north this afternoon providing more isld showers.
High temps still look to top out in the mid 50s to low 60s today.

.SHORT TERM (Now through Friday)...
Issued at 300 AM EDT Thu May 5 2016

Anomalous closed upper low very close to Cincinnati continues to
dive SSE into eastern Kentucky, with a smattering of showers across
southern Indiana. Main challenge through tonight is the evolution of
POPs with the continued battle between cold pool aloft and mid-level
drying.

Either way, expect unseasonably cool temps and plenty of cloud cover
today into this evening. High chance POPs will be focused mainly on
the morning as the current batch of showers moves through. Have
followed cooler NAM MOS for max temps, as abundant cloud cover will
really inhibit any recovery this afternoon. Another weaker vort
pinwheeling around the low could spark a few more showers late this
afternoon into this evening, but will limit that to a slight chance
in our eastern counties.

Skies will clear late this evening and Friday looks like the pick of
the week with upper ridging trying to build in from the west. After
a cool start, expect plenty of sunshine and temps recovering to near
normal.

.LONG TERM (Friday Night through Wednesday)...
Issued at 255 AM EDT Thu May 5 2016

Fairly active and progressive pattern shaping up for the long term,
as we will transition from a NW flow pattern over the weekend to a
mean trof over the Plains and weak ridging over the Southeast CONUS
for much of next week. Forecast confidence, especially in the
specifics and timing, is low to moderate even on Saturday.

A weak impulse late Friday night and Saturday will bring at least
clouds, and perhaps a few showers. Forcing aloft appears weak, as
does the surface reflection, but too much model agreement to
discount. Thus will carry slight chance POPs, mainly across the
Bluegrass region.

Later Saturday a stronger wave dives into the Great Lakes, pushing a
surface cold front southward across Indiana. Exactly when and how
far south this boundary fires on Saturday afternoon will be crucial,
and the GFS/ECMWF both agree on getting precip as far south as the I-
64 corridor by 00Z Sunday, but it`s worth noting that the NAM12 is
noticeably slower, and holds off until later in the evening. Will
favor the warmer NAM MOS for Sat highs as temps tend to overachieve
in this pre-frontal regime. This will support marginal instability
in the presence of enough deep-layer shear to fuel a few strong
storms. This system certainly bears watch for timing, especially
relative to any outdoor plans late Sat afternoon into the evening.

Carried likely POPs Saturday night as showers and storms should
spread south across most of the area. Sunday is a transitional day
as the flow aloft becomes more southwesterly, heralding a more humid
and unsettled pattern. Expect rounds of showers and storms, but any
individual impulses are too difficult to time this far out.
Therefore POPs for any given period are limited to chance, and no
day can yet be pegged as a washout. Temps will run on the high side
of climo, especially by night with a humid air mass and ample cloud
cover.

&&

.AVIATION (18Z TAF Update)...
Updated at 1257 PM EDT Thu May 5 2016

VFR conditions are expected through much of the TAF period.  Only
exception will be for a couple hours at the start of the TAF period,
which may feature some high-end MVFR cigs.  These will quickly mix
out early this afternoon as drier air works in. A stray shower will
be possible at KLEX later this afternoon, but coverage is not
expected to be very high.  Winds this afternoon will continue out of
the north, with gusts to around 20 knots possible through the
afternoon hours.

Overnight, clouds should decrease in coverage as an upper-level low
pulls off to the east.  NNW winds will also slacken, but should stay
up around 6-8 knots overnight.  They will increase to around 10
knots again on Friday with partly cloudy VFR skies.

&&

.LMK Watches/Warnings/Advisories...
KY...NONE.
IN...NONE.
&&

$$

Update.........AMS
Short Term.....RAS
Long Term......RAS
Aviation.......KJD



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