Scientific Forecaster Discussion
fxus63 koax 100536
Area forecast discussion
National Weather Service Omaha/valley NE
1136 PM CST Mon Dec 9 2019
..updated aviation forecast discussion...
issued at 245 PM CST Mon Dec 9 2019
A band of moderate to heavy snow combined with 45 mph wind gusts
lead to visibility down to 1/4 a mile at times and treacherous
travel across much of area this morning. Skies have since cleared
as the snow races east at 45 mph. Our attention now turns to the
cold high pressure settling in behind the departing front. A wider
perspective reveals an upper level Hudson low directing the
northwesterly flow across the Great Plains.
Tonight and tuesday:
Temperatures have improved by a couple of degrees in the past
three to four hours, but remain well below seasonal norms.
Today's highs were set prior to the front passing with numbers
close to 40 f before sunrise. Wind chills dipped to as cold as -10
in northern Nebraska this morning. Tonight's apparent
temperatures will slip sub-zero once again in northern Nebraska
despite diminishing winds with temperatures there close to 10 f.
Skies will be mostly clear overnight with a few passing clouds
closer to the South Dakota state line.
Tuesday's forecast will be a little tricky with a wavering front
in the area and some elevated vorticity. Winds will blow briefly
from the south as the front pushes north. They'll turn north as a
reinforcing shot of cold air settles into the Great Lakes Tuesday
night. GFS, NAM, Euro all in decent agreement of a spot of pops
pushing through the Sioux City area with the sagging front,
bringing a slight chance of light snow to NE Nebraska for a couple
of hours on Tuesday night. Expect a trace of snow at best.
Wednesday through Friday afternoon:
The upper level flow turns more zonal on Wednesday allowing
afternoon highs to improve by about 5 degrees when compared to
Tuesday under the low- angle December sun... at least in southern
Nebraska and Iowa.
A warming southerly wind and continued zonal flow will leave
temperatures pleasantly close to seasonal norms on Thursday and
about 5 degrees warmer to wrap up the work week.
The weekend and beyond:
Long range models suggest a parade of shortwaves bringing
occasional chances for light showers for the weekend. Friday
evening may bring some light stratiform rain that turns to light
snow with strong cold air advection. Maybe a wintry mix will produce another
round treacherous travel Friday night. It would serve to bookend
the work week with Monday morning's ugly commute.
The light precipitation possible on Saturday and Sunday would fall
entirely as snow, with the best chances reserved for the second
half of the weekend. I consider the timing and placement of
showers too uncertain to alter travel plans. Models do not
provide any sort of consensus at this time.
Aviation...(for the 06z tafs through 06z Tuesday night)
issued at 1134 PM CST Mon Dec 9 2019
VFR conditions through the period with a wind shift the primary
concern. Light and variable winds ahead of a surface trough, wind
winds becoming northwest and increasing to 10 to 14 knots by