Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 122332

Area Forecast Discussion
National Weather Service Wilmington OH
632 PM EST Mon Nov 12 2018

Low pressure along the Gulf Coast will move into the Central
Appalachians tonight. Meanwhile a cold front will sweep across
the Great Lakes and Ohio Valley late tonight into Tuesday
morning. High pressure will build into the area on Wednesday,
but another storm system will affect the region late Wednesday
night into Thursday.


Areas of light rain continue to move east northeast into and
across the southern third of the forecast area. Appears that
there may be some expansion in this precipitation to the north
overnight as a short wave moves through the Tennessee Valley. In
addition, a cold front will be pushing into the region later
tonight as a northern stream short wave dives towards the area.
This will lead to additional precipitation across the northwest
parts of the forecast area. Overall precipitation amounts will
be light for the entire forecast area with the highest amounts
in south central Ohio and northeast Kentucky likely no more than
.1 in.

Temperatures will be slow to cool with much of the southern
areas not falling below freezing tonight. However, boundary
layer cooling will allow for a mix or changeover to snow
especially along and north/west of the I-71 corridor. However,
with precipitation amounts expected to be so light, any snow
accumulation is forecast to be a half inch or less. Where
temperatures fall below freezing there could be some slick spots
for the morning commute.


Some light snow and/or rain may still be ongoing early Tuesday
morning with any amounts being quite light. This will move out
early in the morning. In cold air advection, clouds will persist
through much of the day with highs only 5 to 7 degrees above
morning lows. Clouds are forecast to diminish Tuesday night as
high pressure starts to build in. Temperatures will drop into
the lower to mid 20s.


The much below normal temperature trend of recent will continue on
Wednesday as a system slowly approaches from the south Wednesday
night into the first part of the day on Thursday. A compact yet
potent/deep upper level low will slowly pivot northeast into the
southwestern Tennessee valley by daybreak Thursday. Ahead of this,
with good divergence aloft and increasingly supportive jet dynamics,
enhanced large-scale lift and corresponding banded precipitation
will spread northward into the southern Ohio Valley late Wednesday
into Thursday morning. At the surface, meanwhile, a somewhat ill-
defined inverted surface trof extending from the Carolinas westward
into the Tennessee Valley will propagate northward with the better
upper level support lingering a tad further west. Models continue to
be in fairly good agreement showing the arrival of widespread pcpn
by sunrise Thursday moving in from the south. With surface winds out
of the east and a lingering near-surface cold layer, sounding
analysis continues to point at the potential for a brief period of
freezing rain across the Tri-State area, northern Kentucky, and
south-central Ohio Thursday morning before surface temperatures are
able to warm enuf by mid-morning.

The timing and implications of the system discussed above will
undoubtedly change slightly in the coming days as newer and more
high-resolution data becomes available -- although confidence is
increasing in the potential for a light wintry mix of pcpn for the
Thursday AM commute across the southern third or so of the ILN FA.
As the system tracks through the Ohio Valley Thursday afternoon, any
mixed pcpn will have changed to rain just about everywhere before
wrap around cold air on the backside of the upper low begins to
change pcpn back to a mix of rain and snow as the best and most
widespread pcpn begins to lift out of the area Thursday night.

Dry conditions return briefly for Friday before a reinforcing shot
of unseasonably cool air arrives on Saturday as a system tracks
quickly through the eastern Great Lakes. A few rain/snow showers may
be possible Saturday afternoon this the passage of the front, but
kept PoPs at chance for now.

Unseasonably chilly air with highs in the 30s/40s and lows in the
20s are expected for the end of the week.


Areas of light pcpn across southern Indiana and far northern
Kentucky will continue to lift northeast through the evening
hours. This should mainly remain along or just southeast of the
I-71 corridor, so most of the TAF sites will be on the edge of
this pcpn through the first few hours of the TAF period. The
pcpn may gradually fill in through the overnight hours, but
should remain on the lighter side. As the low levels moisten
up, cigs will likely drop into MVFR later tonight. Colder air
filtering into the area should also allow for any pcpn to mix
with snow at times and this could lead to some occasional MVFR
vsbys into the overnight hours. Pcpn should taper off late
tonight into early Tuesday morning, but some MVFR cigs will
likely linger through much of the day on Tuesday.

OUTLOOK...MVFR ceilings and visibilities possible late
Wednesday night into Thursday night.




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