Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
642 am EST Wednesday Feb 10 2016
a large upper trough will slowly move east of the Ohio Valley over
the next few days. This will keep a chance of snow showers through
Wednesday. Below normal temperatures will remain through the rest
of the week. Another stronger cold front will then cross the area
Friday ushering in even colder temperatures for the weekend.
Near term /until 6 PM this evening/...
scattered snow showers have continued near the Ohio River this
morning with some partial clearing further north. This partial
clearing has allowed temperatures to fall into the single digits in
places. Later this morning into early afternoon forecast soundings
on the GFS and NAM begin to steepen low level lapse rates a bit
indicating that snow shower coverage should begin to increase.
Saturation thickness on both the NAM and GFS at kcmh is around
200 mb through the dendritic growth zone while at kcvg saturation
is only around 100 mb thick and doesn't encompass the entire
dendritic growth zone. High res models favor the greatest coverage
across the north and east which makes sense given the forecast
soundings. Current probability of precipitation show this trend so have not made many
changes at all here.
Afternoon high temperatures will again be below normal as the low
level thermal profile remains supportive of highs only around 20
degrees. 850 mb temperatures from the global models are between
-16 and -18 degrees c with low level 1000/ 900 mb thicknesses
around 810 M.
Short term /6 PM this evening through Friday night/...
scattered snow showers are forecasted to come to an end this
evening as drier air moves in from the west. Given the mentioned
above have kept the Winter Weather Advisory as is.
Thursday morning lows will be cold with temperatures in the
single digits thanks to the fresh snow pack and breaks in the
clouds. During the day Thursday surface high pressure will move in
from the west with 850 mb temperatures and low level thermal
profiles remaining very similar to Wednesday.
Friday morning surface high pressure will move overhead allowing
winds to go mostly calm (esp near the Ohio river) with cloud cover
increasing. Given the calm winds and the snow pack lows in the
single digits looks likely. During the day Friday another cold
front will approach the area from the northwest as a potent upper
level low dives south out of the Hudson Bay. At the same time
Friday afternoon an upper level disturbance will rotate around the
upper level low and clip our southwestern zones. Global models
have continued to bounce around on whether or not any
precipitation will come from this system. Upper level lift looks
rather weak and forecast soundings show a near isothermal layer
near -10 from around 900 mb to near 650 mb (via GFS and nam). This
is just warmer than the preferred zone for dendritic growth (-12
to -18 degrees c). Slight chance probability of precipitation more than cover this at
this time do to lack of model run consistency and rather poor
forecasted upper level lift.
Friday night into Saturday morning a strong Arctic front will
cross the area ushering in even colder air into the region.
Long term /Saturday through Tuesday/...
temperatures will struggle to rise on Saturday with cold airmass
Any remaining snow showers will taper off by Saturday evening and
cloud cover will decrease. The combination light winds...mostly
clear skies...and snow on the ground will lead to temperatures
dropping into the single digits to single digits below zero Saturday
Dry conditions will be in place most of the day on Sunday however
expect an increase in clouds through the day in advance of the next
system. Models are in some disagreement on how quickly
precipitation will overspread the area. Have precipitation chances
beginning to move into the region Sunday evening into Sunday night
with better chances during the day on Monday. Although there may be
a brief mix in precipitation across southern portions of the region
generally expect temperature profiles to be cold enough that
precipitation will be in the form of snow. Snow will taper off
Monday night with high pressure and dry conditions moving into the
region for Tuesday.
Aviation /12z Wednesday through Sunday/...
ceilings had lifted into VFR overnight across much of the area but
they do appear to be beginning to lower back down toward MVFR as
snow showers have been gradually filling in across the region.
Expect this trend to continue through this morning as middle level
short wave energy pushes east into our area. This will likely lead
to occasional IFR and lower visibilities for the first several hours of
the taf period.
Low level lapse rates will increase later this morning and into
this afternoon...especially across northeast portions of our
area. This will lead to a continuation of some IFR snow showers
across at the northern taf sites and especially at kcmh/klck.
This activity should begin to die down toward evening as the short
wave shifts east of the area. Some drier air will try to work in
from the west and this should allow for improving sky conditions
toward the end of the taf period.
Outlook...MVFR ceilings and visibilities possible Friday
afternoon into Saturday.
Ohio...Winter Weather Advisory until 10 am EST this morning for
Winter Weather Advisory until 6 PM EST this evening for ohz046-
Kentucky...Winter Weather Advisory until 10 am EST this morning for
In...Winter Weather Advisory until 10 am EST this morning for