Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 281718

Area Forecast Discussion
National Weather Service Louisville KY
118 PM EDT WED SEP 28 2016

...Updated Aviation Discussion...

...Forecast Update...
Issued at 845 AM EDT Wed Sep 28 2016

Near-term guidance continue to show strong support for a band of
showers and embedded storms developing on the south side of the large
upper low just to our north. This band should swing steadily
southeastward as the afternoon goes on. Freezing levels are low and
winds aloft would argue for some gusts mixing down in the stronger
cells. Updated the grids to trend toward those model solutions and
blended current obs.

.SHORT TERM (Now through Thursday)...
Issued at 250 AM EDT Wed Sep 28 2016

A strong vort max will enter the region today as a deep upper low
and cold front dive south into the Ohio Valley.  This weather system
will kick off low topped convection this morning after sunrise in
southern IN with convection expanding and pushing ESE through
central KY during the afternoon/early evening hours.  Model
soundings are supportive of small hail and gusty winds in the
stronger cells this afternoon/early evening.  Of particular interest
is an area from Louisville/Lexington and points northward where a
good pocket of instability is progged to develop providing an area
of enhanced energy for hail/wind production.  Will need to watch
this region for strong storms possibly approaching severe limits.
Quite the gradient of temps are expected today as convection and the
cooler airmass limits highs over southern IN/north central KY to the
upper 60s while south central KY warms into the mid 70s.

Tonight expect convection to diminish in coverage with the loss of
day time heating.  However, will still keep 20-30% POPs overnight as
lobes of vorticity continue to rotate around the upper low sparking
some convection.  Lows will dip into the upper 40s and lower 50s.

For Thurs, expect convection to increase in coverage and strength
with isld storms possible during the afternoon/early evening hours.
Small hail and gusty winds will again be possible with any
convection.  However, with a thick cloud cover anticipated for much
of the day, CAPE values may remain lower than today limiting hail
sizes/gusty wind potential. With the cold core directly over central
KY, temperatures will be limited to the low to mid 60s.

.LONG TERM (Thursday night through Tuesday)...
Issued at 310 AM EDT Wed Sep 28 2016

Thursday Night - Saturday...

The upper low will maintain its influence over the Ohio Valley
through the end of the week.  As it wobbles over our region, expect
continued rounds of showers with isld t-storms possible mainly
during the afternoon/early evening hours.  Convection will increase
in coverage with any one particular vort lobe rounding the upper low
and during peak heating each day.  Did omit t-storm chances Sat
afternoon as the upper low will begin to weaken and pull away to our
north leaving only limited forcing.

Temps will hold in the mid 60s to around 70 for highs both Fri/Sat.
Overnight lows will range from the upper 40s to mid 50s.

Sunday - Tuesday...

Dry weather will return with a moderation in temps for the beginning
of next week as the upper low finally weakens and moves north into
the Great Lakes and southern Canada.  Temps look to rebound into the
70s for Sun/Mon and then low 80s by Tues.  Low temps should range
though the 50s.


.AVIATION (18Z TAF Update)...
Issued at 118 PM EDT Wed Sep 28 2016

Strong/closed upper level low is dropping southward into the Ohio
Valley today. Widespread showers, and a few rumbles of thunder, have
developed ahead of this feature roughly along the Ohio River and I-
64 corridor. Will start SDF out with prevailing showers, with tempo
-TSRA and brief low MVFR or IFR visibilities. Have similar
conditions happening at LEX, but a bit later between 4 and 8 PM EDT.

After the initial rounds of showers and storms, expect a brief lull
through the late afternoon and early evening at SDF, before another
brief round of isolated showers is possible. We`ll then stay VFR
through much of the evening into the overnight, before MVFR ceilings
drop over the region as the upper low settles over the area. At this
point, won`t mention any showers, but expect that scattered coverage
will again be possible as we move into the day on Thursday.

Overall, winds will veer around from a gusty SW direction to a NW
direction through the afternoon and early evening. Expect a
generally steady NW wind or variable wind to then persist through
the end of the cycle.

Other than an hour or two of VCSH possible at BWG later this
evening, will go dry, with only the MVFR ceilings dropping into the
region around dawn.


.LMK Watches/Warnings/Advisories...


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