Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 200754
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
354 AM EDT Sun Aug 20 2017

.SYNOPSIS...
Light to calm winds have taken hold across the area this
morning as high pressure slowly builds in. Above normal
temperatures will persist through Monday ahead of the next cold
front which is currently forecast to push through the area
Tuesday night. Showers and thunderstorms are likely ahead and
along the front, before a much cooler and drier airmass moves in
for the later half of next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Weak surface high pressure has slowly moved into the area this
morning allowing winds to go light and calm. Dewpoint
depressions are sitting near zero this morning with fog already
having formed in Licking county. There is some cloud debris
across our southwestern zones this morning from earlier
convection which might delay river valley fog formation by a
bit. During the afternoon today temperatures will quickly warm
as mid-level heights rapidly rise towards 590 dm. Some high res
models also indicate weak isolated convection trying to form
this afternoon along and ahead of some PVA. Looking at GFS and
NAM forecast soundings though reveals dry air in the mid-levels
with a capping inversion around 700 mb. Even if the cap is not
as strong as forecast dry air entrainment should easily cause
most updrafts to fail.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
Tonight into Monday morning surface high pressure will pull
southeast of the area allowing a return of southwest winds to
the region. During the day Monday the area should remain mostly
dry with forecast soundings remaining capped. The main concern
for Monday will be whether or not there will be any clouds for
the eclipse. The issue looks to be that there will likely be
ongoing convection out towards Iowa which means some convective
cloud debris (cirrus) will possibly spread over the area. For
now have nudged cloud cover up, but there always exists
uncertainty on how opaque this cirrus will be when and if it
arrives.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
A seasonably strong mid level short wave will rotate down across the
southern Great Lakes through the day on Tuesday. As it does, an
associated cold front will push southeast across the Upper Ohio
Valley Tuesday into Tuesday night. Good forcing along and ahead of
the front will combine with increasing instabilities through the day
to produce fairly widespread shower and thunderstorm activity
across our area. the thunderstorm chances should then taper off from
the northwest heading into Tuesday night as the cold front moves
through. Increasing dynamics and strengthening wind fields aloft
will lead to developing deep and mid layer shear along and ahead of
the front through the mid afternoon hours. This will lead to the
possibility of severe storms with damaging wind being the primary
threat.

Surface high pressure will build down across the Great Lakes behind
the front on Wednesday and then remain in place across the region
into the weekend. Both the GFS and ECMWF are showing a secondary mid
level short wave dropping down across the western Great Lakes and
into our area through the day on Thursday. Moisture is pretty
limited so will maintain a dry forecast at the moment, but some
lower chance pops may eventually be needed with this feature.
Otherwise, expect mainly dry and cooler conditions through the
remainder of the long term period with highs mainly in the mid to
upper 70s each day.

&&

.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
Weak surface high pressure will slowly build into the region
this morning with winds mostly light to calm. Dewpoint
depressions are already nearing zero degrees in many locations
with river valleys all but certain to fog in. As the sunrises
this morning fog will slowly burn off allowing conditions to
return to VFR.

This afternoon slightly drier air will build in with only
daytime CU possible. Some high res guidance is trying to get
some very isolated coverage going this afternoon, but think this
is way overdone given the GFS and NAM forecast soundings
(updraft failure from dry air entrainment). Sunday evening,
surface high pressure will be off to our southeast with winds
veering towards the southwest. Besides restrictions from fog
this morning VFR conditions expected.

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

&&

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

&&

$$
SYNOPSIS...Haines
NEAR TERM...Haines
SHORT TERM...Haines
LONG TERM...JGL
AVIATION...Haines



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