Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 270630
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
230 AM EDT WED JUL 27 2016

.SYNOPSIS...
A stalled frontal boundary along or south of the Ohio River will
continue to be the focus of thunderstorm activity through
Wednesday night. On Thursday, an upper level wave will cross
northeast and into south central Ohio, sparking more widespread
activity. This upper level feature will cross east overnight and a
trailing surface low on Friday will mark a slight decrease from
this activity starting Friday night as high pressure builds north
of the region.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Shower/thunderstorm activity that formed over parts of southern IN
and northwestern KY is beginning to move into area. As this
progresses ENE, expect a weakening trend as it moves into area
that was worked over by convection earlier in the day. This
activity will mostly be diurnally driven, so decreased PoPs after
03z leaving the FA dry through most of the overnight period.

Despite rain-cooled air across southern third of CWA, temperatures
are track with forecasted lows for tonight (upper 60s in north to
lower 70s in south). Cloud debris from convection in the region
will persist for the southern third of the FA for the first half
of the night. Will need to monitor clearing trends through the
overnight period for potential fog development for areas that
received heavy rain earlier today (primarily along the Ohio
River). As of right now, expect that mid/high level clouds should
limit widespread fog development for southern parts of FA.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/...
Wednesday will see any ongoing convection from overnight storms
decrease early given an expected unsupportive diurnal trend. There
may however be lingering showers along and especially south of the
Ohio River given the continued stalled surface boundary and
continued influx of moist air from the low and mid atmospheric
levels.

All of the models are showing a marked decrease in coverage during
the day Wednesday with the highest potential laying out over
northern Kentucky. Overnight Wednesday may see an increase in
storms but the feature initiating any overnight convection appears
muddled and highly dependent on a more distinct surface feature
which does not seem a likely scenario at this moment in time.
Thursday will see a marked increase as most of the models are
keying off of a vort max streaming ne ahead of an upper level s/w
and combining with daytime insolation.

Have increased pops Thursday and really ramped them up in the
southeast where all indications show continued storms - similar
to what is occurring at this moment in time. Given this, have
lowered max temps in the southeast to just lower 80s, and could be
even lower depending on where and how long rainfall occurs.

Outside of the max temps being lower in the southeast on Thursday,
numerical guidance were all within a degree or two of each other
for the climatological stations for any given period. It did not
appear to be a large change from what was already in the
forecast.

Storms for any period along and south of the Ohio River will have
a potential to include very heavy rainfall and an increased threat
for flooding given the continued feed of moisture to the region in
question. Strong winds will remain a lesser yet still viable
threat, and large hail chances appear minimal through this time.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
The long term will start with a series of upper level
disturbances moving across the area along with a front stalled
out. This will help to keep the chance of rain in the forecast
almost through the entire extended until Tuesday when weak mid-
level ridging moves into the region.

Looking more into the details, Friday will open up with a shortwave
moving across the region and the leftover frontal boundary from
earlier in the week still across the area. Upper level lift is
sufficient with weak PVA moving across and moisture values remain
above average for this time of year with PWATs forecasted to be
around 1.70". Instability is also present with ML CAPE values around
500 J/kg. As the shortwave exits Friday PoPs will slowly taper off
due to weak subsidence behind the wave.

Saturday through Sunday another weak shortwave trough will remain in
close proximity to the area with a surface front located across the
CWA. This will help to bring the chance of rain right back to the
area. Given the weak upper level trough quickly pulling east the
cold front stalling across the area seems likely. Given the chance
of showers and thunderstorms during the day have kept high
temperatures near climo. Monday into Tuesday as the shortwave trough
exits weak mid-level ridging will then build overhead as mid-level
high pressure builds over the central United States. There still
remains timing differences on when the high will build and how far
it will build east. For now have just trended PoPs down.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
Surface frontal boundary has stalled out e-w parallel to the upper
level flow across northern KY. This front will remain quasi-
stationary before returning as a warm front Thursday.

Abundant low level moisture is present along and just north of
this frontal boundary. A few isold showers will remain possible
overnight but coverage is expected to be too low to mention in the
fcst. Primary concern during the early morning hours will be the
development of fog in this moisture rich environment.

At southern sites of KCVG and KLUK where rain was observed in the
past 24 hours and winds are light expect IFR VSBY/CIG restrictions
in fog. Expect MVFR VSBYs for KILN with the potential for IFR
restrictions.

Expect fog to improve shortly after sunrise Wednesday. The weak
stalled sfc boundary will be the focus for additional diurnally
driven thunderstorms, mainly this afternoon. Have a mention of
VCTS at KCVG and KLUK durg the afternoon being closer to the
frontal boundary.

Winds will remain light and variable for all terminals for
Wednesday.

OUTLOOK...Thunderstorms likely Thursday and possible again Friday
and Saturday.

&&

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

&&

$$
SYNOPSIS...Franks
NEAR TERM...KC
SHORT TERM...Franks
LONG TERM...Haines
AVIATION...AR



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