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Area forecast discussion 
National Weather Service Sioux Falls South Dakota
545 am CST Thursday Nov 27 2014

Short term...(today and tonight)
issued at 306 am CST Thursday Nov 27 2014

A cold start to Thanksgiving day as Arctic high pressure slides
across the area. Will slowly warm through the day as warm air
advection kicks in on the backside of the departing high. In fact
with the low level jet increasing into tonight...southerly winds
will stay blustery through the night...which will allow temperatures
to steady out and even rise a few degrees. So most locations will
probably see their warmest temperatures later tonight as
temperatures rise into the 20s.

Will see increasing clouds from west to east through the day...with
it remaining mostly cloudy into tonight. Best isentropic lift and
low level moisture is focused to our north and east...which is where
most models keep the majority of the quantitative precipitation forecast today into tonight. However
we are still pretty saturated this far despite the
relatively weak lift...think we may still see some scattered
flurries. Best chances are west of the James River this
morning...along and north of the Interstate 90 corridor this
afternoon...shifting into southwest Minnesota and adjacent portions
of northwest Iowa this evening. Anything that does fall will be very
light and should not accumulate. The exception could be in our far
northeast corner from Marshall to Windom. Could potentially see up
to a half inch or so in that area. Expect any light snow or flurries
to be out of the County Warning Area by midnight.

Long term...(friday through wednesday)
issued at 306 am CST Thursday Nov 27 2014

A few concerns through the medium and extended forecasts...despite
relatively dry conditions. The primary focus with the forecast will
be on temperatures Friday through Sunday...along with fog potential
Friday night into Saturday. Warmer air will begin to stream into
the area on Friday as weak southerly surface flow and low level warm
advection increases. We may be dealing with a bit of low stratus
early in the day...and as alluded to in earlier
discussions...development of a weak surface warm front along the
Missouri River may prevent skies from clearing by the afternoon.

Decent setup for fog Friday night into Saturday...given combination
of rapid snow melt and weak convergence zone in the area. Should
stratus fail to clear the area...we may have quick fog development
in the evening. Some uncertainty on temperatures Friday night given
cloud cover and light southerly flow. Have bumped up readings a few

Saturday shows the potential to be a very warm day across the
region. By daybreak...850 temperatures will be pushing 10-12c with
925 temperatures as high as 15c along the Missouri River. These readings
alone would push nearly +2 South Dakota from normal levels for late November.
The questions again fall on impacts of fog/stratus and rather poor
mixing. A quick glance at cips analog data suggests as high as a
40% probability for reaching 60 degrees the southern areas of the
County Warning Area...with the real warm air and potential for 70 degrees not too
far away in central Nebraska. Depending on the orientation of a
weak surface trough through the is also feasible the far
northern County Warning Area could struggle to reach 40.

The cold front will begin to push through the area Saturday
night...with colder temperatures only oozing slowly southward. In
fact...cold advection aloft really does not develop until daybreak
Sunday. That being said...have slowed the secondary surge of winds
and colder temperatures closer to Sunday. High pressure will
slide through the area bringing cold temperatures for Sunday and
Monday. With the core of the surface high passing nearby by daybreak
Monday...have lowered lows...and still may not be low enough. A
bit of a rollercoaster temperature ride begins next week...but no
remarkable systems appear to be on the horizon at this time.


Aviation...(for the 12z tafs through 12z Friday morning)
issued at 542 am CST Thursday Nov 27 2014

Expect middle level clouds to move into the area today. Am watching
an area of MVFR stratus west of the James River...which could
impact khon for a period middle to late morning. Can not completely
rule out MVFR ceilings at the other taf sites for a period today...but
at this point think it is unlikely. Scattered flurries are also
possible today into tonight with the clouds...but nothing
significant expected.


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


Short term...chenard
long term...dux

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