Area Forecast Discussion
Issued by NWS Wilmington, OH

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000
FXUS61 KILN 112048
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
348 PM EST Sat Nov 11 2017

.SYNOPSIS...
A large area of high pressure over the Great Lakes will move
off the New England coast tonight. A weak low pressure system
will then track across the area Sunday, bringing rain to the
area. Cooler and dry will settle back in for Monday and
Tuesday.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Zonal westerly mid level flow with large surface high pressure
building east across New England tonight. Focus shifts to
amplifying shortwave over the northern plains. Slower trend with
this feature has been the case the past few days and this trend
continues. Expect just high level clouds through most of the
night with mid level clouds and low level moisture increasing
toward sunrise. Expect a non-diurnal temperature trace with lows
near 06z and then quasi-steady or even a rise of degree or two.
Lows to range from the mid/upper 20s far north to the mid/upper
30s southwest.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Amplifying mid level shortwave to track from the upper MS Vly
across the Ohio Valley Sunday. This will induce a weak surface
low that tracks through southern Ohio Sunday evening. Expect
pcpn to develop toward midday in the west in waa pattern ahead
of the low. Rain to overspread ILN/s FA during the afternoon,
becoming categorical by Sunday evening. Max wet bulb zero temps
in the 0-6km layer suggest a cold rain event. Expect highs from
the lower/middle 40s nw to the lower 50s se.

Progressive s/w and surface low to track east across Ohio Sunday
evening, with the pcpn coming to an end overnight. As the
surface low tracks east CAA on the northwest side may cause a
mix with some snow briefly prior to ending. Clouds to hang on
through most of the night with some partial clearing into the
west late as surface high begins to nose in. Low temperatures to
range from the lower 30s nw to the upper 30s southeast.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
The base of a mid-level trough is forecast to be east of the ILN CWA
by Monday morning, leaving the long term forecast period to start
out dry. A large area of surface high pressure will then move into
the region later Monday and into Tuesday, though there will not be
much of a change in air mass, leading to relatively stagnant
temperatures both days (highs in the middle to upper 40s).

Going through the rest of the week, there are two main concerns to
look at. The first is with a developing cold front on Wednesday.
Model agreement is in good shape regarding timing and placement for
this system, and categorical PoPs will be brought through the area
in association with the front. This front is attached to a surface
low that will be moving north of Lake Superior on an eastward track,
with the mid-level trough strengthening as it moves across the Great
Lakes. It was a close call with regards to temperatures early
Wednesday morning, but with some slight warming possible before
sunrise in the southerly flow, this forecast will keep all
precipitation rain. Ahead of the front, temperatures should be
slightly warmer -- with highs in the lower to middle 50s.

It will be a relatively quick transition through high pressure on
Thursday and the return to southerly flow on Thursday night into
Friday. The next system, moving in for Friday and Friday night, is a
little more complicated -- and thus it is not a surprise that model
solutions are not as consistent in its depiction. There will
initially be a surface low and mid-level trough moving across
Canada, but a secondary trough is expected to develop ahead of a jet
streak coming across the central plains. This will allow for another
surface low to develop very close to the area, which may allow for a
relatively quick passage of both warm and cold frontal processes
across the Ohio Valley. Timing is the biggest issue, with slow
solutions (12Z ECMWF) and faster solutions (06Z GFS) running a solid
12 hours apart. PoPs will be kept in the chance category until this
issue is resolved, though it is certain that most (if not all)
locations will receive precipitation at some point during the Friday
/ Friday night time frame. With lots of upper support and wind
energy, forcing should not be in question with this system. Have
also used non-diurnal temperatures heading into Friday morning, and
moved high temperatures up slightly on Friday from the previous
forecast (middle 50s to near 60).

Behind this system, the first part of next weekend looks drier in
a cold advection pattern.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
Large area of surface high pressure over the eastern Great Lakes
will build east into New England tonight. Expect VFR conditions
with high level CIGs through the remainder of the afternoon into
tonight. Surface low pressure will develop in the lower Ohio
Valley and track east across southern Ohio Sunday evening.

Mid level CIGs will develop early Sunday and lower to 3500 to
5000 feet with rain showers arriving during the afternoon. Have
MVFR CIGs developing after 18z at 30 hour KCVG taf site as the
low levels moisten up with rain showers becoming widespread.

East winds at less than 10 kts will become southeast at 6 kts or
less tonight.



OUTLOOK...MVFR ceilings and visibilities possible Sunday night and
Monday.

&&

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

&&

$$
SYNOPSIS...AR
NEAR TERM...AR
SHORT TERM...AR
LONG TERM...Hatzos
AVIATION...AR



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