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Area forecast discussion 
National Weather Service Wilmington Ohio
944 PM EDT Tue Oct 25 2016

high pressure will keep dry weather over the region through
tomorrow morning. Low pressure traveling across Northern Ohio
will bring showers Wednesday night into Thursday morning. High
pressure and a dry airmass will return for Thursday night and


Near term /until 6 am Wednesday morning/...
the main focus for the update this evening was to adjust sky grids
based on current satellite trends, and to assess the impact that
the cloud cover is having on temperatures. The thickest cloud
cover is currently stretching across the central / north-central
sections of the cwa, running from north of Indianapolis through
Chillicothe. Temperatures in this area are still in the upper 40s
to near 50, and may not fall quickly overnight, especially with
light northeasterly flow failing to go calm. Dewpoints are still
fairly dry -- mid 30s through most of the cwa, and closer to 40 in
the southwest. This at least provides the potential for
temperatures to fall enough to support frost, though the winds and
clouds may make it difficult. No confidence in any decision to
expand the frost advisory, so it will remain in place, with the
best chance for areas of frost in the extreme northern /
northeastern sections of the iln County Warning Area.

Previous discussion >
high level clouds continue across the central part of the County Warning Area this
afternoon and are forecasted to remain over the area for the
greater part of the night. At the same time, surface high
pressure will slowly pull east. Given the high clouds overhead
this would in general inhibit optimal radiational cooling but with
winds mostly light across the eastern zones frost will still be
possible. Have gone ahead and issued a frost advisory for our
eastern zones to account for this.


Short term /6 am Wednesday morning through Thursday night/...
during the day Wednesday a shortwave will push east across the
Midwest with surface high pressure eroding from the area. In
response to the shortwave a surface low pressure will form. A warm
front will then pull north across the area. As this happens highs
will warm into the mid to upper 60s across the southwest with
highs in the upper 50s across the far north. Most of the area will
remain dry Wednesday though as the shortwave remains just far
enough west.

Wednesday night into Thursday morning iln will move into the
divergent region of the trough axis with most of the positive vorticity advection remaining
north of the area. Surface low pressure will then track just north
of the area Thursday morning. Pwats ahead of the system rise to
around 1.10" (~1.05" on GFS and 1.20" on nam) with both NAM and
GFS soundings never fully saturating. Instability will also be
hard to come by as the event will occur at night. The GFS has
almost no instability at all (surface or elevated) while the NAM
does have some elevated instability (100 - 300 j/kg of cape).
Shear values ahead of the low are impressive. Both the GFS and NAM
forecast soundings are showing surface-1km shear values approaching 40
kts. Surface-1km srh is also forecasted to be around 400 m2/s2. Due to
the lack of instability though have kept only slight chance
thunder in the grids. A surface cold front will then push through
the forecast area Thursday morning ushering in cooler and drier
conditions. The cold front will be weak though and only push
temperatures back down to normal values for this time of year.


Long term /Friday through Tuesday/...
high pressure will be centered over the area Friday morning. This
will allow for dry conditions and light winds. The area of high
pressure will push off to the east Friday into Friday night.

Winds will pick up on Saturday out of the southwest. Wind gusts of
30 to 35 mph will be possible. These warm winds out of the
southwest will bring much above normal temperatures to the area.
High temperatures are expected to be around 15 degrees above normal,
however still around 5 to 7 degrees below record at this time. The
forecast high on Saturday at cmh is 75, record 80, normal 60. The
forecast high on Saturday at cvg is 78, record 83, normal 62. The
forecast high on Saturday at day is 75, record 82, and normal 59.

A frontal boundary will work through the region on Sunday. Moisture
is limited with this feature and therefore went dry to chance for
precipitation chances. The best chance of some light shower
activity will be across northeastern portions of the forecast area
around cmh.

High pressure will then work into the area Sunday night into Monday.
There is not a significant precipitation signal for the end of the
long term and therefore went with dry conditions.


Aviation /02z Wednesday through Sunday/...
a fairly solid area of mid and high clouds has been in place
today, with a few very light rain showers or sprinkles in the
Dayton area late this afternoon. With no low clouds expected to
develop during the taf period, VFR conditions are expected through
the next 24 hours. Fog potential will also be very limited for
kluk, with clouds in place and winds that are unlikely to become
completely calm.

Light northeasterly flow overnight will turn to southeasterly on
Wednesday, and will increase in intensity to around 10-15 knots.
Winds will shift again to the south on Wednesday night.

Outlook...MVFR ceilings and visibilities are possible from
Wednesday night through Thursday night.


Iln watches/warnings/advisories...
Ohio...frost advisory from 4 am to 9 am EDT Wednesday for ohz046-056-


near term...Haines/hatzos
short term...Haines
long term...Novak

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