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Area forecast discussion 
National Weather Service Wilmington Ohio
359 am EST Sat Jan 31 2015

high pressure will remain across the area today keeping conditions
dry. A developing low pressure system will move through the Ohio
Valley Sunday into Monday bringing widespread snow and rain to the
region. A much colder air mass will move in behind the low
pressure system for Monday.


Near term /through today/...
the center of high pressure will slip eastward today. High clouds
will work into the region throughout the day. Skies should be
sunny this morning...then partly to mostly cloudy this afternoon.

On the back side of the high winds will become south-southwest and will bring
warmer air into the region. The Mercury should push into the lower
30s across the northwest...rising to the upper 30s around the Ohio River.


Short term /tonight through Monday/...
focus shifts to low pressure system that will develop in the
Southern Plains tonight and will streak NE into the Ohio Valley
Sunday. 00z models have continued the trend of the previous
runs...which takes the low a little farther north pulling more
warm air into the region. There will be a significant gradient of
snow across the forecast area ranging from less than an inch in northern Kentucky
to 8-10 inches in west central Ohio.

Ahead of the low...isentropic lift develops tonight allowing for a
mixture of snow...sleet and possibly some freezing rain to
overspread the area. A couple of inches of snow accumulation will
be possible across the northern counties tonight...with less than an
inch possible south of I-70.

Temperatures will warm ahead of the low Sunday changing the
precipitation to rain. The exception will be along I-70 where a
mix will be possible and in west central Ohio where pure snow is
still expected. Another 3-7 inches is possible on Sunday across
Mercer...Auglaize and Hardin counties.

The low works east of the region Sunday night. Colder air will
work in on the backside of the system changing all the precipitation
back to snow.

There is still enough uncertainty to keep Winter Storm Watch up.
Hopefully with one more run of the models a trend will become clear.

The winter storm will be coming to an end on Monday morning...with
some light additional snow accumulations possible in the Scioto
valley between 12z and 18z. On the back side of the strengthening
surface low...gusty north-northwest flow will lead to strong cold advection
through the Great Lakes and Northern Ohio valley.

Temperatures will drop into the upper 20s to lower 30s tonight.
With the warmer air expected for Sunday highs around the Ohio
River will reach around 40...the middle 30s around I-70 and the lower
30s in the northwest. Temperatures will drop to around 10 in the northwest
Sunday night...and the teens elsewhere. Highs will only rebound
to the teens in the north and lower 20s in the S on Monday.


Long term /Monday night through Friday/...
cold and dry high pressure will move over the region by Tuesday
morning. Although some clouds may still persist...radiational
cooling conditions will be otherwise favorable...allowing for
temperatures in snow-covered areas to approach or even drop below
zero degrees. Combined with some wind (generally increasing
slightly by 12z)...wind chills appear likely to drop into advisory
criteria for the northern sections of the forecast area.

Forecast specifics become much more uncertain for Tuesday and
beyond. Quick west-northwest flow aloft will be set up across the northern tier
of the Continental U.S....with several weather disturbances expected to move
through. An initial shortwave will weaken as it moves into the Great
Lakes on Tuesday...with another cold front expected to move through
sometime between Wednesday night into Thursday. In advance of the
front...temperatures appear likely to be somewhat mild...and values
were raised in the forecast for this time period. However...behind
the front...another lengthy period of cold conditions is expected to
continue through the weekend. Precipitation with the cold front will
likely be mainly snow...but current model forecasts are fairly
subdued on accumulation potential.


Aviation /08z Saturday through Wednesday/...
VFR conditions will be found over the taf sites through most of
the period. At the tail end a nose of precipitation will affect
western sites after about 3 or 4z which will lower visibilities and ceilings
to MVFR range. At this time...rain may mix with snow at cvg/luk before the
warmer air on southerly winds push the mix north and mix out any
lower ceilings in the 6-12z time frame. Kday and Kiln stand a
better chance of seeing plain snow as a start to this winter

Kcmh/lck will likely not see any precipitation until after 6z.

Outlook...significant snow accumulations...IFR ceilings and
visibilities likely through Sunday night with MVFR conditions
possibly continuing into Monday.


Iln watches/warnings/advisories...
Ohio...Winter Storm Watch from late tonight through Monday morning
for ohz026-034-035-042>046-051>056-060>065-070>072.
In...Winter Storm Watch from late tonight through Monday morning
for inz050-058-059-066.


near term...sites
short term...sites
long term...hatzos

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