Area Forecast Discussion
Issued by NWS Wilmington, OH

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000
FXUS61 KILN 262359
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
759 PM EDT TUE JUL 26 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 WEDNESDAY 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 WEDNESDAY 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 /23Z TUESDAY THROUGH SUNDAY/...
A stalled frontal boundary will continue to linger across southern
parts of the area through the TAF period. For this evening, SHRA/TS
activity across southern IN and northwestern KY will move ENE and
is expected to dissipate with loss of daytime heating.

For overnight period, expect primary concern to be BR/FG
development at southern sites of KCVG and KLUK. With calm winds
and sct mid/high deck, expect that very moist low level
environment should support BR development as far north as KILN.
Expect MVFR VSBYs for KCVG and KILN and the potential for VLIFR
VSBYs for KLUK. There exists some uncertainty as to how thick and
persistent mid/high clouds will be for southern parts of area
which will ultimately determine expanse of BR/FG development for
aforementioned sites. Drier air should keep VFR VSBYs at KDAY,
KCMH, and KLCK.

For Wednesday, a weak sfc boundary will be oriented along and just
south of the Ohio River, providing the possibility of SHRA/TS
development during peak diurnal heating. CAMs continue to
struggle in this weakly forced but unstable regime, and
therefore, there is little confidence in coverage and timing of
potential activity. While environment for KCVG and KLUK will be
most supportive of SHRA/TS, confidence remains limited enough to
keep all sites dry through the remainder of the TAF period. 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...KC



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