Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 102131

Area Forecast Discussion
National Weather Service Wilmington OH
431 PM EST Sat Dec 10 2016

High pressure will weaken across the Ohio Valley this afternoon. A
low pressure system will eject northeast from the Plains into the
Great Lakes Sunday into Monday. Snow will develop ahead of this
system tonight and then a mix of rain and snow is expected Sunday
before precipitation ends early Monday. High pressure returns late


Still have a few flurries flying across the CWA this afternoon,
particularly across west central Ohio and east-central Indiana. No
accumulation is expected from the flurries through sunset.

Focus then shifts to the next system which will begin to affect
portions of the CWA tonight. Low pressure will eject out of the
Rockies and into the central Plains tonight. And as high pressure
over the Ohio Valley moves into the Mid-Atlantic, a return flow
will set up, allowing the low levels to moisten up and warm
advection will also start to kick in and produce more clouds.
Isentropic lift will also promote the development of snow,
although much of our guidance suggest a fairly sharp southern cut
off where accumulating snow will occur. At this point in time,
the highest confidence in accumulating snow looks to be just north
of the Interstate 70 corridor, favoring a GFE/SREFS blend.

Highest snowfall accumulations are forecast to reside across our
northern most counties, namely Auglaize, Mercer and Hardin and a
Winter Weather Advisory has been issued. Further south of this
area toward the Interstate 70 corridor, snowfall accumulations are
expected to remain below Advisory criteria but enough to
potentially result in slick travel late tonight/early Sunday.


Snow continues Sunday morning mainly across the far northern
portion of the CWA, but precipitation will overspread the entire
area during the afternoon/evening as a favorable jet develops
over the CWA ahead of low pressure which will move into the upper
Midwest by days end. In addition to supporting precipitation, the
southwesterly jet will also result in the rain/snow line shifting
north through the day where much of the CWA is likely to
experience rain by late afternoon, except for perhaps the extreme
northern counties within the Advisory area.

Surface temperatures will likely continue to rise into the
overnight hours, with rain being the primary p-type across the
CWA. Then, as low pressure moves through the Great Lakes late Sunday
night, this will allow a cold front to move through from the west,
ending the precipitation chances Monday morning. The remainder of
Monday dries out and clouds may even break for some sunshine later
in the day.


With the departing frontal system leaving the area becoming under
the influence of a shallow ridge over the southern CONUS...but low
level moisture will linger for Monday night. So despite Cold air
advection over especially the northern half of the forecast
area,there will only be occasional breaks in cloud cover. There will
be a pretty tight gradient of temperatures on especially Tuesday
into Tuesday night with the passage of the upper low over central
and then SE Ontario, with the weak ridging in the south. The only
potential for precipitation will come in the form of light snow
showers in NW flow with the passage of the upper low, but limited
moisture available.

More significant Cold advection and dry conditions will continue the
below normal temperatures through the work week, with single digit
overnight lows Wednesday night and Thursday night. For Friday into
Saturday, moisture returns to the region with the passage of
another shortwave, with precipitation onset beginning as snow and
then changing over to rain during the day on Saturday.


Some MVFR stratocu has redeveloped this afternoon across much of
the area with still a few flurries at times. It does look like the
southwest edge of these lower clouds is beginning to erode and as
the low level flow continues to back, expect this trend to
continue through the rest of the afternoon. As the low clouds
erode, mid level clouds will stream in from the west through the
evening hours in a developing WAA pattern. As some better
isentropic lift develops and we start to moisten up, snow will
develop/spread into northern portions of our fa later tonight. It
looks like there could be a fairly sharp cutoff to the southern
edge of this, with the models in a bit of disagreement as to how
far south this will be. Overall, it looks like the most likely
scenario is with the cutoff somewhere along or possibly just
south of the I-70 corridor. This will put our northern TAF sites
on the edge of the lower cigs and vsbys associated with the snow
so for now will generally allow for MVFR conditions at
KDAY/KCMH/KLCK to account for the uncertainty. The better forcing
will shift off to our north through the morning hours on Sunday,
allowing for any pcpn to taper off at the TAF sites.

OUTLOOK...MVFR/IFR ceilings and visibilities possible Sunday
night into Monday morning.


OH...Winter Weather Advisory from 10 PM this evening to 6 PM EST
     Sunday for OHZ026-034-035.


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