Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 220555

Area Forecast Discussion
National Weather Service Wilmington OH
1255 AM EST Sun Jan 22 2017

Temperatures will remain mild through Wednesday before cooling
to more seasonable levels by the end of next week. A storm
system and surface low pressure center will ride up into the
lower Ohio Valley and Tennessee Valley region Sunday and then
move very slowly northeastward along the eastern slopes of the
Appalachians. This system will keep our weather unsettled
through Monday.


Showers continue to develop in central Ohio this evening. An axis
of moisture convergence extends from this activity southwest
towards the Cincinnati area. Recent HRRR/RAP runs have shown a
strong signal that further precipitation will develop along and
east/south of the I-71 corridor. So have increased PoPs for
overnight but still kept them in the chance category for now. This
is mainly falling out of a mid deck, so rainfall amounts should
remain light. Temperatures will remain quite mild with a drop of
only a few degrees from evening temperatures.


Storm system poised to push into the Ohio Valley by Sunday will
produce some overrunning precipitation from south to north
through the day. Areas along the Ohio River should expect to
see rain developing by around sunrise or just after. Rain should
push northward from there, entering our northern most zones by
late afternoon. Forecast soundings did suggest a hint of some
elevated instability. As such continued to included a mention of
thunder. However, better instability appears to hold off until
later in the day as the storm center gets closer to our area and
generally across the southern third of our area.


A significant change in the overall mean flow will occur during the
coming week, with ridging building into the western United States
and troughing in the east. This will signal a return to more normal
winter like temperatures late in the week along with the chance for
periodic light snow showers and rain showers from Wednesday night
into Friday night.

However, before this transition occurs we will be focused on low
pressure at the surface and aloft that will be moving out of the TN
Valley northeastward up the Appalachians from Sunday night into
Monday. This will bring rain to the forecast area. There is fairly
good agreement among the models on this scenario and agreement that
the heaviest rains will remain south and east of the forecast area.
The 12Z NAM is an outlier with QPF in our area, generating in excess
of 1.5 inches in parts of the southern forecast area from late
Sunday into Monday night. However other models and GFS ensembles and
the SREF support lower rainfall totals during this time, and this is
reflected in WPC guidance and the NDFD forecast.

In the wake of the low pressure moving off to our northeast,
somewhat cooler air will move into the area at the start of the
week. However temperatures will remain above normal, and
temperatures will warm even more on Wednesday ahead of an advancing
cold front.  Brief ridging at the surface and aloft will build into
the OH Valley and Great Lakes Tuesday, ahead of the advancing cold
front. The cold front will move east of the area late Wednesday, and
this will signal a downward trend in temperatures that will continue
through the end of the week.


Showers that formed earlier this evening have since started to
dissipate with all TAF sites currently VFR (except KLUK). During
the day today an upper level low over the TX/OK border will
organize and push east with an arm of PVA moving across our
southern zones. In association with this upper level lift a band
of showers with potentially some thunder will work its way north
and weaken as they push towards the Ohio river. Over the last
couple of days models have struggled significantly on the track of
the upper level low and this band of PV that is forecasted to push
north. The GFS/NAM initially had the low further north meaning
greater chances of rain while the ECMWF had the low further south
meaning a lower chance of rain. The new 22.00z NAM is now further
south and has trended towards the ECMWF. Looking at high res
models there has also been a drying trend keeping the band further
south. This is further supported by NAM/ GFS forecast soundings.
Due to the mentioned above have trended TAFs drier.

Sunday evening into Monday morning the upper level low will get
pulled northeast pulling the rain northeast with it. Based off the
track of the low KDAY could remain dry through the issuance.
Remaining TAF sites look far enough south or east as to receive
precipitation. Uncertainty still remains though as the track of
the low and PV remains muddled. As the low approaches cloud bases
will also begin to lower meaning VFR conditions will give way to
MVFR conditions this evening and potentially IFR conditions Monday

OUTLOOK...MVFR/IFR ceilings and visibilities possible into Monday
night. MVFR ceilings may linger into Tuesday. MVFR ceilings
possible again Wednesday and Thursday.




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