Scientific Forecaster Discussion
fxus63 koax 140918
Area forecast discussion
National Weather Service Omaha/valley NE
318 am CST Thu Nov 14 2019
..updated forecast discussion...
issued at 311 am CST Thu Nov 14 2019
Today through Saturday night...
forecast concerns in the short term will be fog/stratus potential
Thursday night and Friday morning...then light precipitation
potential Saturday night.
The shortwave that produced the freezing rain has pushed to the
east over Illinois. Skies have cleared over much of the area
within the area of subsidence and as high pressure built in,
however, farther west over northeast Colorado a trailing shortwave
within the longwave trough was producing a mix of rain and snow.
The baroclinic zone between the warmer air to the west and the
cold temperatures over the local area is over west central
Nebraska. Within this area, clouds will linger.
Several intrusions of cold air will affect Minnesota and Wisconsin,
however the forecast area will largely escape these. General
ridging today through Friday and southwest flow ahead of an
approaching trough will mean that temperatures will return to over
the next several days. Highs today in the 30s and 40s with 40s and
50s for Friday-Sunday.
Not sure on the extent of fog tonight into Friday morning. Winds
will be quite light initially with dewpoints on the rise and
dewpoint depressions are low. A strong low level inversion is
forecast to be in place and ground fog and stratus are possible.
The sref probabilities for fog are 70 to 90 percent. The href
ensemble mean has the low level/high level clouds at 90 to 100
percent. The low level jet begins to increase over central
Nebraska into our western cwfa so this may inhibit the fog. For
now will include some patchy fog and bump up the clouds and pass
on to the next shift.
The forecast is mainly dry. A few sprinkles/drizzle may try to
develop late tonight into Friday morning with the increasing low
level jet, otherwise, the next chance for light precipitation would
be with the trough/front Saturday night. Temperatures are mostly
above freezing, so did include a light rain with it's passage and
can refine precip type as we get closer.
Sunday through Wednesday...the trough will be over or through the
area by Sunday and how quick the return flow sets up will vary
temperatures from west to east from the 50s to the 40s. Warming
will develop ahead of a weak clipper type system. Highs Monday
should range from 50 to 60 degrees. Clouds and light showers
could hold temperatures down for some though. Energy on the
backside of the long wave trough could have some sprinkles with it
Monday night, before shifting east into Iowa Tuesday. Highs
Tuesday-Wednesday...are expected to be above normal...in the 40s
Aviation...(for the 06z tafs through 06z Thursday night)
issued at 1111 PM CST Wed Nov 13 2019
Subsidence on the backside of a short-wave trough moving into the
mid MS valley has contributed to decreasing clouds across eastern
NE and western Iowa over the past several hours. That trend should
continue overnight with prevailing VFR conditions expected. Light
northwest winds will switch to westerly before becoming light and
variable by Thursday evening.