Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Sioux Falls South Dakota
615 PM CST sun Feb 7 2016
Short term...(this evening through monday)
issued at 325 PM CST sun Feb 7 2016
Upper level low presently seen on water vapor rotating through
northern Minnesota...with trailing shortwave sliding out of the
southern portions of our County Warning Area this afternoon. Radar and observations
indicating an area of snow showers drifting southward through the
middle and lower Missouri River valley with this wave. Would expect
this activity to slide out of the area through the late afternoon as
the shortwave drifts off into southeastern Nebraska/southern Iowa by
evening. Still seeing some convective snow showers through eastern
North Dakota and northeastern South Dakota...and these slide into
the northern portions of our County Warning Area during the evening...though being
mainly instability driven may become less numerous by middle evening.
Models have generally handled todays system very
poorly...overestimating quantitative precipitation forecast amounts and misplacing precipitation too
far to the east. Current experimental hrrr and rap have a better
handle on current trends so followed them more closely for the
forecast into tonight. What has verified better today has been the
winds...with Wind Advisory criteria being met. Even
so...visibilities have remained just either side of 2 miles even
when snow is occurring as temperatures have been above freezing and
much of the snow has settled and become wet...preventing any lofting
of the snow. As for the remainder of the night...models...if they
can be believed...still hinting at some development of light snow in
our east this evening into the overnight hours as the upper level
low over Minnesota rotates southward. The question becomes will this
be enough to cause significant visibility reductions to areas in the
current Blizzard Warning. Based on todays trends would think that it
is on the low end of probability...but after coordination with
neighboring offices elected to leave the headline in place for
now...though delayed the onset of the warning. Dependent on the
trends through the evening...future shift may have to adjust the
headline as needed. In any event...any snowfall looks to remain very
light...at generally around a half an inch or less.
Otherwise...the strong winds will persist through much of
Monday...before tapering downward from the west in the afternoon.
Any very light snow showers may persist in our far east through middle
day...then come to and end by afternoon. Temperatures will be cooler
on Monday behind the system...topping out in the upper teens far
east to lower 30s far west.
Long term...(monday night through sunday)
issued at 325 PM CST sun Feb 7 2016
Again today...very little change in the synoptic pattern running
through the upcoming week and into next weekend. Fairly pronounced
sine wave across the Continental U.S....bringing cold weather to the eastern
half of the Continental U.S....and warm weather to the western half. We will
be stuck in-between these two airmass through much of the week...with
weak impulses of warmer air trying to move east leading to light
snow chances. Again...given the subtle nature of these
wave...models having a hard time figuring out when the best focus
for precipitation will be found. Considerable oscillations in
European model (ecmwf)/GFS guidance continues...and at this point...can only see
having slight to low end chance probability of precipitation. Of more certainty is that no
major snow producing systems are on the horizon through next
As far as temperatures are concerned...there will likely be a
significant gradient across the region. Temperatures in central
Minnesota may be in the teens...while readings in south central
South Dakota could climb into the 30s each day. Todays guidance has
nudged colder air a bit further westward...so as a result
temperatures have also trended a couple degrees colder for the end
of the week.
Aviation...(for the 00z tafs through 00z Monday evening)
issued at 614 PM CST sun Feb 7 2016
Occasional MVFR conditions in light snow showers and blowing snow
through about midnight. After this ceilings will waver from VFR to
MVFR through the remainder of the period.
South Dakota...Wind Advisory until noon CST Monday for sdz038-039-052>056-
Blizzard Warning until noon CST Monday for sdz040.
High Wind Warning until 9 PM CST this evening for sdz050-057-063.
Minnesota...Wind Advisory until noon CST Monday for mnz098.
Blizzard Warning until noon CST Monday for mnz071-072-080-097.
Blizzard Warning until noon CST Monday for mnz081-089-090.
Iowa...Wind Advisory until noon CST Monday for iaz001-012-020-031.
Blizzard Warning until noon CST Monday for iaz002-003-013-014-
NE...Wind Advisory until noon CST Monday for nez013-014.