Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
1249 am EST Monday Dec 9 2013
low pressure traveling up the Appalachians will bring a light mixture
of wintry precipitation tonight. High pressure will build in
briefly on Monday. Another weak system will bring a good chance
for snow Monday night and Tuesday.
Near term /until 6 am this morning/...
the focus for the forecast update tonight is on the continued
threat of freezing drizzle. Reports are being received from
several different locations in the iln County Warning Area of hazardous Road
conditions due to light ice accumulations. These reports have been
important because the precipitation is very difficult to detect on
radar (even in vcp31)...as it is both light and low to the ground.
Overall...there did not appear to be any reason to favor one part
of the County Warning Area over another in terms of coverage...so fzdz was
included for all counties. However...some deeper moisture is still
expected to work into the southeastern County Warning Area over the next few
hours...which may lead to a brief possibility for legitimate rain
showers (either freezing or liquid depending on surface temps).
The fzdz threat will get squeezed into the Interstate 71 corridor
by 06z...as temperatures in the southeastern County Warning Area warm solidly
above freezing...and precipitation chances end behind the cold
front moving into the western County Warning Area. Non-diurnal temperatures were
continued through the period (though a slight increase may be
possible during peak heating on monday). No major changes were
needed to sky grids...which are pretty solidly 100-percent through
the next 12 to 18 hours.
No changes were made to the advisory headlines...which will stay
up until 4 am (which should cover the threat timing outside of
maybe the far northern/northeastern cwa).
Short term /6 am this morning through Tuesday night/...
precipitation should end by Monday morning as weak high pressure builds
in. High temperatures are forecast to range from the upper 20s
northwest to the middle 30s southeast.
NAM indicates a jet streak rounding the base of an upper trough
Monday night that will provide lift. With the presence of sufficient
moisture...there is a good chance that a band of snow will form
Monday night into Tuesday. Light snow accumulations will be
possible with this band of snow. Highs in the middle 20s to lower 30s
are expected on Tuesday.
Long term /Wednesday through Sunday/...
split middle level flow with northern stream dominating from the northern plains
through the Great Lakes. Surface high pressure over the region Wednesday to
slide off to the East Coast with weak system tracking through the Great
Lakes. Most favorable moisture/lift to stay to our north...so have
maintained a dry forecast Wednesday.
Cold temperatures to persist with temperatures around 15 degrees
below normal...with highs Lower/Middle 20s northwest to the lower 30s southeast.
Cold air reinforced with Arctic high pressure to build in for
Thursday. Thursday early morning lows to be about 20 degrees below
normal...ranging from single digits over the west where snow cover
exists to near 15 southeast. Highs to range from near 20 northwest to the
upper 20s southeast.
A slight moderation to temperatures expected Friday on the back side
of surface high building southeast of the Ohio Valley. Highs to range from the
upper 20s north to the middle/upper 30s south.
Middle level flow backs westerly ahead of weak perturbation late Friday
night and Saturday. Will continue chance probability of precipitation with the best probability of precipitation
across the south where best moisture exist. In warm air advection pattern will allow
precipitation to mix with rain across the central zones and change to
rain for a period in the south before changing back over to snow
Saturday night with the passage of a frontal boundary. Highs still
about 5 to 10 degrees below normal...ranging from the lower 30s
north to the upper 30s south.
Models showing cyclogenesis over the southeast and then tracking up the East
Coast next Sunday. After a short break in precipitation the
potential exists for light precipitation to re-developing late Sat night
into Sunday. Have trended forecast toward colder European model (ecmwf) solution keeping
precipitation all snow showers.
Aviation /06z Monday through Friday/...
with a southerly shift in wind...temperatures are warming up that
the freezing portion of the drizzle over the County Warning Area is coming to an
end. LIFR ceilings and IFR visibilities will combine to put some of the
Airport towers in the soup with supplemented visibilities in the LIFR to
vlifr range for the next few hours. As ceilings lift towards
daybreak...the tower visibilities will be indicative of what is occurring
at the surface and will likely go without restrictions relatively
soon today. MVFR ceilings will persist through the day and drop back
down towards 0z with some visibility reductions in br.
A shot of snow will be overspreading the region in the 6-12z time
frame...only affecting cvg taf for the most part.
Outlook...snow expected late Monday night and early Tuesday...with IFR
Ohio...Winter Weather Advisory until 4 am EST early this morning for
Kentucky...Winter Weather Advisory until 4 am EST early this morning for
In...Winter Weather Advisory until 4 am EST early this morning for