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fxus63 koax 122329 
afdoax

Area forecast discussion
National Weather Service Omaha/valley NE
529 PM CST Thu Dec 12 2019

..updated aviation forecast discussion...

Discussion...
issued at 312 PM CST Thu Dec 12 2019

Overview:
small chances for light precipitation tonight into
Saturday night continue with colder temperatures on Saturday and
Sunday.

This afternoon and tonight: several weak mid-level disturbances
will move across the area over the next few days. At the surface,
a a weak surface low moved overhead and to the northeast, dragging
a surface front along with it. Ahead of this front, temperatures
were able to climb into the upper 40s to lower 50s with temps in
our north and behind the front in the mid 20s where some snow
cover still exists. In addition, low clouds have persisted across
our northern counties through much of the day and these do
continue to spread south and east this afternoon but do expect
these to diminish here later this afternoon as the low-level warm
air advection regime moves out of the area.

For the overnight period, a surface low will again move across the
forecast area with weak low-level warm air advection developing late
tonight into early Friday morning. This will support the chance for
light precipitation across northeast Nebraska and into west-central
Iowa. In addition, weak forcing aloft from an approaching mid-level
shortwave will allow precipitation to continue along the Missouri
River valley and across west-central Iowa through Friday morning.
Forecast soundings indicate a mix of freezing rain and/or sleet,
mixing with snow, and eventually warming over to light rain. As
for quantitative precipitation forecast amounts, model variability makes this forecast
challenging, but am trending on the lighter side of amounts (only
a couple hundredths, if that) and discounting some of the higher
amounts off of models like the 12z NAM. Although a quick look at
the 18z NAM shows it has backed off on heavier quantitative precipitation forecast amounts.

By Friday night, another small chance for light precipitation is
possible as another weak mid-level shortwave trough tracks through
the area. This could bring light precipitation to portions of our
southwestern County Warning Area. Accumulations look to remain under a few
hundredths of an inch. In addition, an Arctic front will move
through the area during the afternoon with the strongest push of
cold air moving through Friday night.

Saturday and Saturday night: temperatures will remain cold with
highs from the teens and low 20s and lows in the single digits to
near 10. Otherwise, the time period should remain dry.

Sunday and monday: latest model guidance continues to show a mid-
level trough amplifying over the Central Plains Sunday night into
Monday with the GFS showing the most amplification,leading to
heavier quantitative precipitation forecast with a more northward extent. By contrast, the European model (ecmwf)
and Canadian continue to suggest the best accumulating snow
potential to our south. Confidence is beginning to increase that a
swath of heavier snow will remain to our south across northern
Kansas and Missouri with much less, if any along the I-80
corridor.

Tuesday and beyond: drier and warmer conditions are expected as
mid-level heights increase across the Central Plains.

&&

Aviation...(for the 00z tafs through 00z Friday evening)
issued at 524 PM CST Thu Dec 12 2019

IFR ceilings will linger at ofk for a few more hours, then
ceilings will be VFR for the remainder of the taf period at all
sites. Winds will be light overnight but then will gradually
become more westerly during the day tomorrow. A few light snow
flurries will be possible at ofk and Oma Friday morning, but
confidence is not high enough to include this in the taf at this
time.

&&

Oax watches/warnings/advisories...
NE...none.
Iowa...none.
&&

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