Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 161346
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
946 AM EDT Wed Aug 16 2017

.SYNOPSIS...
A weak frontal boundary will stall across the area this morning,
offering a threat for isolated showers. After some morning fog, a
disturbance approaching from the southwest will combine with the
stalled boundary to produce a threat of showers and storms this
afternoon and night. A stronger frontal system will swing through
the Ohio Valley on Thursday afternoon and evening bringing a
higher chance of more widespread shower and thunderstorm activity.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
With showers generally dissipating across the area earlier this
morning, mostly clear skies have been left in place, outside of
the southern sections of the CWA. Though there is not a
significant gradient in surface dewpoints, a gradual advection
of moisture a little further aloft is expected as the day
progresses, which should add clouds (from current stratocumulus
to additional cumulus development) to the region over the next
few hours. Though MLCAPE values may increase into the 500-1000
J/kg range today, absent any notable low-level forcing, there
should not be significant coverage of precipitation -- with
the best chances near the greater moisture in the southern and
southwestern sections of the CWA. One change for this forecast
is a 20-percent chance of showers added to the entire CWA by
mid-afternoon, with the atmosphere appearing favorable for a few
very light showers to develop just about anywhere. Nonetheless,
most locations should still remain dry.

Made some near-term decreases in sky grids, but temperatures
appear to be on track with the previous numbers.

Previous discussion >
A few showers continue to linger across central Ohio in the
vicinity of weak frontal boundary. Due to lack of upper level
support with mid level ridge over the region, expect this
activity to continue to weaken early this morning.

Mostly clear skies, light winds and moist low level has lead to
patchy fog across ILN/s area. This shallow fog will quickly
improve with sunrise.

Shortwave ridging to move across the Ohio Valley downstream from
wave moving across the plains today. The morning and first part
of the afternoon expected to be dry. Moisture increases with
boundary layer cape values of 1000-1500 j/kg into the southwest
this afternoon. Have thunderstorm chances developing into the
southwest with increasing chances from southwest to northeast
through the later afternoon hours. Temperatures will continue
above normal with todays highs similar to yesterday in the mid
and upper 80s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
Mid level ridge to shift east with flow backing as s/w tracking
into the MS VLY tonight. Thunderstorm chances will increase,
especially over the nw counties as low level convergence/warm
front develops. Have continued high chance pops late tonight.
With increasing moisture and clouds temperatures will be mild
tonight with lows generally in the lower 70s.

Ongoing storms to start Thursday especially invof of the warm
front. Moisture increases as 30-35 kt southwesterly low level
jet comes into play with precipitable water values increasing
to near 2 inches. Boundary layer cape values of 2000-2500 j/kg
expected to develop across the area Thursday in the warm sector.
Bulk shear of 35-40 kts across the southern Great Lakes along
with this instby will support convective development with some
organized clusters. Isolated damaging wind gusts will be
possible along with the potential for heavy rain and local
flooding. will mention this threat in the HWO product. Warm
temperatures to continue with Thursdays highs from the lower 80s
northwest to the upper 80s southeast.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Cold front will be moving east Thursday night. Showers and
thunderstorms are likely to be ongoing Thursday evening, diminishing
during the overnight hours as daytime heating dwindles and frontal
forcing departs. Some thunderstorms may contain strong wind gusts
early Thursday night, and localized flooding will be possible in an
atmosphere containing about 2 inches precipitable water. A few
thunderstorms may even linger on Friday, mainly over eastern
locations where greater residual instability and moisture will be
evident.

After a weak ridge brings a brief dry period Friday night, a
disturbance traveling across the Great Lakes may trigger a few
thunderstorms during peak heating on Saturday. Dry weather is
indicated for Sunday when a large area of high pressure is forecast
to be centered to the east. Isolated thunderstorms cannot be ruled
out for Monday in the increasingly humid return flow around the
high. A better chance for thunderstorms will exist on Tuesday due to
a strong short wave and cold front.

High temperatures starting near normal in the low to mid 80s will
boosted by warm advection to the mid and upper 80s by the end of the
long term.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
A weak frontal boundary which has stalled out across central
Ohio, continues to offer a few isolated showers east of Columbus.
Coverage is too limited to mention in the TAF forecast. Skies
continue mostly clear this morning. These clear skies and light
winds has led to the development of areas of fog. The fog is
shallow and will improve quickly after sunrise. Increasing
moisture through the day will combine with an approaching mid
level short wave to produce an increasing chance of showers and
thunderstorms from the southwest. Have kept the TAFs dry through
the daytime period with an enhanced chance tonight as a warm
front lifts north across the area. Have kept VFR conditions, but
have a mention of VCTS overnight to account for this chance of
thunderstorms.

Southeast winds at less than 10 kts will veer to the south late
tonight into Thursday.

OUTLOOK...Thunderstorms possible Thursday and Thursday night.

&&

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

&&

$$
SYNOPSIS...Binau/AR
NEAR TERM...Hatzos/AR
SHORT TERM...AR
LONG TERM...Coniglio
AVIATION...AR



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