Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Sioux Falls South Dakota...correction
643 PM CST Monday Feb 8 2016
Short term...(this evening through tuesday)
issued at 303 PM CST Monday Feb 8 2016
Strong winds and persistent light snows continue to cause significant
travel issues in the tri-state area this afternoon. While extremely
strong winds have been on a downward trend...we are continuing to
see wind gusts approaching 40 miles per hour over the eastern County Warning Area as winds at
the top of the mixed layer remain near 50 knots. Continued
convective streamers of stratus moving across the region are having
no issues producing snowflakes...as the majority of the layer
resides in the dgz.
Trends into the evening continue to suggest weakening winds...albeit
very slowly. Have concerns that we may likely stay well mixed
through the overnight hours...especially areas east of I-29...with
rap/hrrr soundings indicating the potential for 40 knot gusts all
the way until midnight especially over the Buffalo Ridge. There is
also the possibility that any remaining strato-cumulus in the area will
produce snow flurries. Will be issuing an advisory for areas
currently in a Blizzard Warning through midnight so as to not
advertise any drastically improving conditions once Blizzard
Warning expires at 00z.
Surface ridging will attempt to slide eastward on Tuesday...with
another breezy day over Minnesota/Iowa. Have included patchy blowing
snow as gusts approaching 30 miles per hour continue to be possible through
early afternoon. Highs on Tuesday will struggle to reach 20 degrees
east of the James River Valley...with highs approaching 30 toward to
MO River Valley.
Long term...(tuesday night through monday)
issued at 303 PM CST Monday Feb 8 2016
Northwesterly upper level flow remains locked in place for the
remainder of the week. The big question will be where the baroclinic
boundary sets up across the Dakotas.
Models remain uncertain regarding how far east the boundary will set
up into Tuesday evening...with potential impact across northwest
into south central South Dakota at least through the early morning
hours. Think that there is enough weak low level lift for some light
snow or flurries along our far western border. Stronger forcing and
lift arrives Wednesday morning as an approaching shortwave dives
southward and the baroclinic zone advances east into southeast South Dakota.
Models are in better agreement with placement of this feature...with
light snow forming along and east of the James Rives as the middle
level wave approaches... however the European model (ecmwf) is about 6 hours quicker
with the onset than the rest of the operational models. Snow exits
the area late Wednesday afternoon into Wednesday evening...and could
produce a quick inch or so of accumulation with some fairly high
snow ratios in our eastern half. The high temperature gradient will
be substantial from west to east...ranging from highs near 10 along
our eastern border...to the lower or middle 30s in south central South Dakota.
We potentially see another wave dropping southeast through the
northern plains on Thursday night into Friday...but will keep
mention of only slight chance probability of precipitation with uncertainty in the location
of the boundary and timing issues. The GFS keeps the area largely
dry while the Gem and European model (ecmwf) develop light snow. It does appear that
this feature will bring a reinforcing shot of cooler air...with lows
dropping well below zero Friday night.
Upper ridging to our west finally advances into the High Plains
later Saturday into early next week. Temperatures will likely warm
overnight Saturday night...leading into much warmer temperatures
Sunday and Monday.
Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 1128 am CST Monday Feb 8 2016
Strong winds and blowing snow will remain the main focus
today...especially along and east of the i29 corridor. Widespread
IFR and LIFR conditions will continue through the afternoon...with
gradually improvement to MVFR visibilities from west to east this
afternoon. Winds will persist around 25 to 40 knots in this
area...then gradually decrease late afternoon through the
overnight. Despite decreasing winds...overnight conditions will
remain breezy overall. VFR ceilings will also return from west to
east through this evening.
South Dakota...Winter Weather Advisory until 6 PM CST this evening for sdz040-
Wind Advisory until 6 PM CST this evening for sdz039-054-060-061-
Minnesota...Winter Weather Advisory until 6 PM CST this evening for mnz098.
Winter Weather Advisory until midnight CST tonight for mnz071-
Blizzard Warning until 6 PM CST this evening for mnz071-072-080-
Iowa...Winter Weather Advisory until 6 PM CST this evening for iaz001-
Winter Weather Advisory until midnight CST tonight for iaz002-
Blizzard Warning until 6 PM CST this evening for iaz002-003-013-
NE...Winter Weather Advisory until 6 PM CST this evening for nez014.
Wind Advisory until 6 PM CST this evening for nez013.