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Area forecast discussion 
National Weather Service Sioux Falls South Dakota
620 PM CDT Friday Oct 9 2015

Short term...(this evening through saturday)
issued at 340 PM CDT Friday Oct 9 2015

Settling in for a fairly quiet short term. Will have a swath of high
clouds move across the area this evening...which will help to keep
temperatures from falling too quickly in the east where surface ridge axis
lingers at late day. Otherwise...the night will feature an
increasing surface gradient across the area. In fact...winds aloft
increase to 30 to 35 knots for a time in the 1000-1500 feet above ground level layer.
With strong inversion in place at a favorable depth...will likely
see a late night and early morning enhancement in winds
along/downstream of Buffalo Ridge...although wind direction is a
bit off optimal for maximum potential.

Warmer is the main message for the start of the a deep
southwest flow set up across the area. System moving well north will
help to induce an eastward surge in the warmer air aloft...and while
inversion will probably somewhat limit the potential warming...even
shaving off some of the depth of mixed layer will still yield middle
70s to middle 80s for most. Some better drying could sneak into the far
west which could push afternoon relative humidity closer to 25 percent...but
fortunately located with some lesser surface winds compared to east
where winds will be stronger 20 to 30 miles per hour...but with somewhat higher
relative humidity in the upper 30s to around 40 percent. While fire danger
calculates out to moderate...those areas with a greater percentage
of cured grasses or fields will find a fractionally greater fire

Long term...(saturday night through friday)
issued at 340 PM CDT Friday Oct 9 2015

Saturday night...a surface trough of low pressure will move eastward
into our southwest zones by late at night. This will have an effect
of relaxing the flow a little bit...but winds will still be
southerly. Therefore because of this...trended toward the more mild
bias corrected lows and especially the raw model bias corrected
values. Many of the more conventional MOS type values looked too
chilly given the southerly flow. This stands to reason however as
any guidance which is influenced by climatology will be too cool.

The aforementioned surface trough will continue to move eastward
across much of the forecast area on Sunday...but a short wave will
induce some cold air behind it. Therefore a cold front will follow
the trough late Sunday and Sunday night. Ahead of the front on
Sunday...very abnormal warmth still looks very likely...with record
or near record highs across northwest Iowa...southwest Minnesota...extreme
northeast Nebraska and extreme southeast South Dakota south of Sioux Falls. Did
forecast Sioux City to tie their record high of 90 on Sunday...but
have Sioux Falls 2 degrees below the record high. Northwest winds
will certainly kick up behind the front with Stout speeds of 35
knots not too far off the surface Sunday night and Monday. The wind
speeds are strong enough on Monday overall at 25 to 40 miles per hour that it
will likely induce a high fire danger. In addition...southwest Minnesota
could press Wind Advisory type wind speeds as their winds average 32
to 42 miles per hour.

After the very warm day on Sunday...Monday will be substantially
cooler but with highs still slightly above normal. Continued the
trend of following raw model values for highs on Monday...and for
that matter lows Sunday night.

The extended still looks dry with temperatures continuing to be a
bit above normal on Tuesday and Wednesday. But another cold front
will dive southward Wednesday night which will tail the highs down
to around normal on Thursday and Friday with lower 60s common. After
Monday...Thursday looks to be our next breezy to windy day which
could affect fire danger. The deterministic European model (ecmwf) and GFS were not
too different this go around in showing a northwest flow aloft and
the cold front on Thursday...therefore performing mental gymnastics
of blending the models was not really needed this time.


Aviation...(for the 00z tafs through 00z Saturday evening)
issued at 619 PM CDT Friday Oct 9 2015

VFR conditions expected through the taf period. Low level wind
shear will develop for a period tonight...after 06z at khon and
after 11z at kfsd.


Fsd watches/warnings/advisories...
South Dakota...none.


Short term...Chapman
long term...mj

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