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000
FXUS61 KILN 201930
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
330 PM EDT Sun Aug 20 2017

.SYNOPSIS...
Above normal temperatures will persist across the Ohio Valley
through Monday ahead of a cold front. The cold front will bring
showers and thunderstorms on Tuesday, then drier and cooler air
moves in for the rest of the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Afternoon cumulus have developed across the CWA, and there`s
even a couple of showers across Auglaize and Hardin Counties at
19Z. HRRR has been consistent in showing some shower activity
across central Ohio this afternoon/early evening. Still believe
the relatively dry/warm air aloft would limit coverage of
showers and also preclude convection from growing very tall, but
per radar trends and consistency with the HRRR among other
models have introduced isolated showers for the next few hours
across portions of central Ohio.

Any showers along with cumulus will dissipate close to sunset.
Then looking at infrared imagery it appears there will be some
high clouds poised to move across the CWA overnight, especially
later at night due to dissipating upstream convection. With
clouds, fog should not be widespread nor dense, but still expect
patchy fog near river valleys.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
Expectation is for any nocturnal upstream convection to have
dissipated by the time it would make it into the CWA early
Monday, although it`s not out of the question lingering showers
make it into the far northwest CWA. Either way, some high
clouds will be left behind for Monday morning. More cumulus are
expected by afternoon as well, and therefore have started to
trend the sky forecast upward a little for Monday, and it`s
possible that much of the CWA could wind up more partly cloudy
than mostly sunny for Monday. In addition, latest guidance
suggests the potential for convective development in the
afternoon/early evening mainly across the northwest portion of
the CWA. Larger scale forcing is still best well northwest of
the CWA, but moisture looks better and models suggest sufficient
CAPE to generate a few cells as long as any capping erodes.
Maxima will rise into the upper 80s, perhaps even hitting 90 in
a few spots. Factoring in dewpoints in the mid 60s will yield
heat index values into the mid 90s on Monday.

Much of any convective activity on Monday would likely
dissipate after the sun sets, but as a cold front approaches
will continue with very low pops across the northwest corner of
the CWA late at night.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
The main focus for the long term period will be the potential for
severe weather and flash flooding on Tuesday.  Thunderstorms will
begin to move into northwestern portions of the forecast area
Tuesday morning.  In addition cannot rule out some isolated
convection along and just southeast of Interstate 71 during the late
morning and into the afternoon hours.  These storms will have a
damaging wind and hail potential.

As the line of storms across northwestern portions of the forecast
area move towards the southeast it will encounter a better
environment with higher, although not substantial, cape values.
Expect the main threat with the line to be damaging winds with
locations northwest of Dayton having the lowest threat and a higher
threat along and just southeast of Interstate 71.  With the flow
orientation believe that the wind threat south of the Ohio River
will be a little less, however isolated damaging winds will still be
possible.  With the orientation of flow and the potential for the
multiple rounds of thunderstorms, flash flooding will also be a
concern generally southeast of Interstate 71.  The cold front will
move through Tuesday night. This will be followed by cooler and
drier conditions for several days.

With good CAA Wednesday and Thursday increased cloud cover
substantially with cu expected to develop during the day on both of
these days.  Expect less cloud cover on Friday and Saturday as we
lose the CAA.  Temperatures Wednesday through Saturday will
generally be in the 70s across most locations.

Another system begins to approach for Sunday so there will be an
increase in cloud cover and precipitation chances will begin to move
back into the region.  Temperatures will also be slightly warmer on
Sunday with WAA.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
Cumulus have already developed this afternoon, although with
limited vertical extent. HRRR continues to suggest a few
showers developing later this afternoon or evening, potentially
affecting KCMH/KLCK but believe it`s too dry/warm aloft and
therefore kept TAFs dry.

Cumulus will dissipate this evening with the setting of the sun.
Then expect some cirrus overnight particularly late and into
Monday morning due to upstream convection. This may interrupt
fog formation somewhat, but at least river valley locations
should see patchy fog and thus KLUK and also KLCK have inclusion
of visibility reductions. In addition to high clouds, more
cumulus build ups are expected Monday late morning/afternoon
under southerly flow.

OUTLOOK...Thunderstorms are likely Tuesday into Tuesday
evening.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.

&&

$$
SYNOPSIS...BPP
NEAR TERM...BPP
SHORT TERM...BPP
LONG TERM...Novak
AVIATION...BPP