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000 
FXUS61 KILN 201112
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
712 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 /11Z SUNDAY THROUGH THURSDAY/...
Weak surface high pressure is just east of the area this morning with
most TAF sites VFR. Cloud debris from overnight convection has 
helped to hold back fog formation at most locations. 

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...Dense Fog Advisory until 10 AM EDT this morning for OHZ056-065-
     074.
KY...None.
IN...None.

&&

$$
SYNOPSIS...Haines

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