Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 040604

Area Forecast Discussion
National Weather Service Wilmington OH
104 AM EST Sun Dec 4 2016

High pressure that was over the area this afternoon will pull east
Sunday as an upper level disturbance quickly moves towards the
Great Lakes. High pressure will then briefly build back into the
Ohio Valley on Monday. Another upper level disturbance will move
over the area Tuesday afternoon bringing the chance of rain back
across the region. Much colder air will then work into the region
for the second half of the work week.


Surface high pressure to build east across the region as mid/upr
level ridge axis builds into Ohio by sunrise. Expect mostly cloudy
sky conditions with the region remaining dry until after sunrise.
Have tweaked temperatures slightly cooler in some locations due
to trends. Expect lows from near 30 far northeast to the mid 30s

Previous discussion...
Surface high pressure was centered directly overhead this
afternoon with overcast skies across the region. An upper level
low was noted on the water vapor over the Baja of California with
pieces of PVA ejecting off towards the northeast. There is also a
shortwave located over the Mountain West that is headed east. The
PVA from the upper level low looks to remain just south of the
area with the shortwave still west of the region. Therefore have
kept the region dry through the 6 AM Sunday morning. Given the
persistent cloud cover across the region have gone above guidance
for Sunday morning lows.


Sunday morning a shortwave trough will approach the area from the
west with weak isentropic upglide commencing across the Ohio
valley. The shortwave will across the midwest will push east and
then take on a negative tilt and clip the area. Looking at the
300 K and 295 K surfaces shows that condensation pressure deficits
don`t really approach zero until Sunday afternoon into evening.
Precipitation will be fighting dry air in the low levels with
forecast soundings being slow to fully saturate. Looking at high
res models precipitation doesn`t really arrive until Sunday
afternoon. Looking at the thermal profiles across the area they
mostly support rain. With that being said, snow could mix with
rain across the north. Precipitation amounts will likely be a
tenth of an inch or less.

Monday afternoon, surface high pressure will build back into the
region with forecast soundings showing some breaks in the clouds.
850 mb temperatures Monday are around 3 degrees C which would
support highs in the mid to upper 40s.


Mid level short wave energy will eject northeast across the
Tennessee Valley through the day on Tuesday as an associated surface
low moves up across the upper Ohio valley. There are some model
timing differences with this as the 12Z NAM is about 6 hours faster
than the 12Z ECMWF while the 12Z GFS is somewhat in between, but
closer to the slower ECMWF. Will trend toward the slower solutions
and have a decent pop gradient north to south across our area at the
start of the long term period. Higher pops will then overspread the
rest of the area through the morning hours and then continuing into
Tuesday afternoon. Low level thermal profiles appear warm enough to
keep precipitation all rain through the day on Tuesday with highs
ranging from the lower 40s northwest to the lower 50s in the
southeast. Precipitation will taper off quickly from west to east
Tuesday evening as the short wave weakens and moves off to the east.
Some cooler air will filter in behind the system but the pcpn should
be over before it is cold enough to change any of it over to snow.

A broad trough will develop over the central United States by mid
week and then shift quickly east through through the end of the work
week. Short wave energy rounding the base of the trough will lead to
an increasing chance of precipitation Wednesday night as an
associated strong cold front pushes east across the area. This will
usher in a much colder airmass through the end of the week. The 12Z
GFS has trended faster with the cold push than the ECMWF and this
will ultimately affect temperature trends Wednesday afternoon into
Thursday and how fast any pcpn chances over to snow. Highs on
Wednesday will range from the upper 30s northwest to the mid 40s
southeast. Precipitation Wednesday night may start as a rain/snow mix
but as the cooler air begins to move in, it will transition over to
all snow. However, the models have trended drier with this feature
so would expect any accumulations to be fairly minimal.

Much colder air will then settle into the region through the end of
the work week as 850 mb temperatures drop down into the -14 to -16
degree celsius range. In somewhat cyclonic low level flow and with
possible fetches off of the warm water of the Great Lakes, will hang
on to some lower end pops for snow showers Thursday into Friday.
Depending on the exact timing of the strong cold push, we may likely
have non diurnal type temperatures on Thursday with highs then on
Friday only in the 20s. We will quickly transition into a more zonal
flow pattern by Saturday, allowing for bit of a moderation in


Surface high pressure will move off to the east today. This will
allow an upper level disturbance to move toward the Great Lakes.
Clouds will thicken and lower through the morning hours. Decent
warm, moist advection/ascent ahead of the disturbance will bring
light rain to the terminals later this afternoon into this evening.
As it rains for a period, ceilings will lower into the MVFR
category and then eventually the IFR category. Visibilities for
the most part will remain MVFR.

The upper level disturbance will move east/northeast away from the
region tonight. Rain will end, but low clouds will persist in the
IFR category. High pressure is then expected to build into the
region on Monday.

OUTLOOK...MVFR/IFR ceilings to linger into Monday morning.
MVFR/IFR ceilings and MVFR visibilities expected Tuesday with
rain. MVFR ceilings to linger Tuesday night into Wednesday




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