Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 041656
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
1256 PM EDT Sat Jul 4 2015

...Updated Aviation Discussion...

...Forecast Update...
Updated at 1233 PM EDT Sat Jul 4 2015

Isolated to very widely scattered showers have begun to develop
across portions of east and south central Kentucky. Currently these
showers are moving at a decent rate and should not cause any water
problems. However, they will be closely monitored through the
afternoon for training. Activity should decrease late this afternoon
before ramping up again this evening as the upper level trough
nears. Made only some minor adjustments to the grids. The forecast
is in pretty good shape.

.SHORT TERM (Now through Sunday)...
Issued at 300 AM EDT Sat Jul 4 2015

The synoptic pattern this morning features a general trough across
the eastern CONUS due to a large upstream ridge across the west
coast.  This pattern will slowly deamplify through the short term
period, but chances for showers/storms will continue, mainly across
southern and eastern KY.

The radar is finally quiet early this morning as a mid-level trough
pushing through the area has shunted the better moisture transport
off to the east/southeast.  Expect this general trend to continue
today, with PWATs of just over an inch entering the northern CWA by
this afternoon.  A frontal boundary currently draped across central
KY will only slowly sag south today, likely stalling somewhere in
the vicinity of the KY/TN border.  Therefore, while the main slug of
deep moisture transport will be shunted off the east/southeast,
still think we will see some scattered storm development along/near
the boundary this afternoon into early this evening.  Given
generally unfavorable upper-level support and the aforementioned
moisture transport being shunted to the southeast of the region,
will cautiously allow the Flash Flood Watch to expire.  Am a bit
concerned that coverage right along the boundary may be enough to
warrant perhaps an isolated flooding issue or two today across
southern KY as storms will once again be slow-moving, but think the
widespread threat has ended so will go ahead and let the headline
expire.

By tonight, an upper-level low will slowly push into TN, crossing
through KY during the day on Sunday.  Moisture transport and ascent
will once again ramp up mainly on the eastern side of this system,
thus have upped pops into the likely category for Sunday across
portions of southern and eastern KY.  Coverage will be substantially
less across northern KY and southern IN.  Will have to watch this
system closely as soundings out of KLEX show PWATs of 1.75+ inches
and a skinny CAPE profile.  In addition, showers/storms will be
slow-movers given the weak tropospheric flow.  Therefore, we may
once again be dealing with some hydro issues as this system pushes
through.

Temperatures will be dependent on convection, but highs today and
tomorrow should climb into the low to mid 80s, with overnight lows
tonight in the mid to upper 60s.

.LONG TERM (Sunday night through Friday)...
Issued at 300 AM EDT Sat Jul 4 2015

Still expecting a lull in an otherwise wet pattern to be ongoing
Sunday night and Monday, with weak surface and upper ridging to our
north and east. Limiting factor in forecast confidence is the
eventual behavior of a disturbance that is progged to move through
the Tennessee Valley. NAM/ECMWF are fairly bullish with this
impulse, and if this solution verifies it could remain wet in our
southern and eastern zones, particularly along the Cumberland
Escarpment. Will still dry things out by late Sunday evening, and
limit Monday POP to a 20-30% chance in the heat of the day, which
may be too generous north of the Parkways but too conservative
farther south and east. Temps actually back near climo for this part
of the week, as cloud cover should not be that extensive.

By Monday night/Tuesday POPs will ramp up from the west as low
pressure swings through the upper Great Lakes, and drags a cold
front into the Ohio Valley. This front will hang up somewhere in or
near the forecast area, and focus showers and storms for much of the
rest of the work week. Impulses riding along the front will be
difficult to time, but also have the potential to disrupt the
otherwise diurnal POP trend. Best chance for any strong storms would
be Thu night/Fri as a better-defined upper shortwave scoots across
the Great Lakes and strengthens the westerlies. Temps near normal or
just a bit cooler by day, but just above climo by night as clouds
and abundant moisture limit diurnal ranges.

&&

.AVIATION (18Z TAF Update)...
Issued at 1253 PM EDT Sat Jul 4 2015

Ceilings have finally lifted to VFR at all sites early this
afternoon. VFR conditions will continue through the afternoon and
much of the evening hours. Drier air will remain in place over SDF
so VFR conditions are expected through the TAF period.

More moisture will remain in place for LEX and particularly BWG. A
few showers may affect BWG this afternoon, so have added in VCSH.
However, the showers may stay just to the south of the airport. Any
activity should end by evening. Some light fog looks to develop at
both these sites again tonight. LEX should have a bit more dry air
working in, so have kept ceilings higher. BWG will have calm winds
and plenty of low level moisture, so think conditions could be
similar to this morning with IFR ceilings and visibilities. Once
again, conditions will improve by mid to late morning tomorrow.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&

$$

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




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