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Area forecast discussion 
National Weather Service Bismarck ND
548 PM CST Sat Nov 28 2015

issued at 548 PM CST Sat Nov 28 2015

No significant changes were made with this update. Light snow over
western South Dakota would appear a bit more robust than most model guidance
would have US believe...but it is indeed weakening with northward
movement like model simulations suggest so we will hang onto only
low probability of precipitation near the South Dakota border overnight. The other issue tonight is
going to be potential fog development...which the most recent hrrr
run from 22 UTC suggests could be more widespread /further south/
with lower visibility than its prior few iterations. We will be
monitoring trends the next few hours to see if any expansion of
our fog mention is necessary in the forecast.


Short term...(this evening through sunday)
issued at 222 PM CST Sat Nov 28 2015

Current surface analysis places high over the Midwest bringing
very light southwesterly winds to the region. Upper level analysis
places persistent upper low near the Great Basin with leading
wave bringing snow to western South Dakota. Quiet weather
continues over our area.

For tonight...aforementioned wave will lift into the area
overnight with cloud cover increasing over southern locations.
With that said...models continue to agree on a mainly dry solution
overnight...and have actually dried things out more in the latest
run. Therefore...will only keep low chances along our far southern
tier. Towards the north...forecast soundings along with high-res
models suggest fog forming over the far north overnight and
spreading southerly in areas that remain mainly clear. Have added
areas of fog to the forecast and will have to keep an eye on this
to see if coverage needs to be adjusted.

On Sunday...upper low stretches towards northeast Wyoming keeping
many parts of the area...especially the south...cloudy through the
day. This will keep temperatures on the cooler side while winds
remain light and southerly.

Long term...(sunday night through saturday)
issued at 222 PM CST Sat Nov 28 2015

The main focus for the long term is snow chances Monday into

A closed low over the mountain west will slowly propagate eastward
over the next several days. The exact track of this low will
determine how much or little snow portions of North Dakota
receive. Models continue to vary with respect to the track of the
low by a hundred miles or so. The European model (ecmwf) and Canadian bring the low
near Sioux Falls and through Minneapolis. This track favors snow
accumulation for southern North Dakota. Meanwhile the GFS and sref
push the low further east into Iowa and Wisconsin. This track
would leave most of western and central North Dakota with very
little precipitation. Utilized a blend of ensembles and
deterministic guidance for this forecast. This yielded snowfall
amounts around half an inch around I-94 and closer to 4 inches
across far southern James Valley. While the greatest amounts are
expected to remain south of I-94...these amounts could change
drastically over the next day or so as this system evolves.


Aviation...(for the 00z tafs through 00z Sunday evening)
issued at 548 PM CST Sat Nov 28 2015

Lower ceilings and possibly a little light snow will move north
out of South Dakota tonight and into southwest and parts of south
central ND after 06 UTC. The highest probability of MVFR or
perhaps local IFR ceilings is over southwest ND in the khei and
kdik areas. Fog with IFR or LIFR conditions is also possible
tonight and Sunday morning...especially in northwest and north
central ND.


Bis watches/warnings/advisories...


short term...jjs
long term...aj

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