Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kfsd 061823 

Area forecast discussion
National Weather Service Sioux Falls South Dakota
1223 PM CST Fri Dec 6 2019

Short term...(today and tonight)
issued at 315 am CST Fri Dec 6 2019

Seeing stratus lying over much of the area early this morning, and
the challenge will be how much/how quickly these low clouds
dissipate today. The overall theme from model relative humidity time sections is
for the clouds to generally erode from the south and east through
the afternoon. Otherwise, it will be a cooler day as cold high
pressure slides across the region. Highs will range from the 20s
over most of the area, with some lower 30s through the MO river

By later this afternoon and tonight the surface ridge axis will
drift off to the east of our area, with a southerly flow returning
on the backside of the high. This will allow for some moderation in
overnight lows compared to this morning, though will still have
temperatures drop into the upper teens and 20s overnight.

Long term...(saturday through thursday)
issued at 315 am CST Fri Dec 6 2019

Much better recovery will be realized on Saturday with a strong
southerly low level flow across the region. Looking at highs in the
upper 30s to mid 40s. It will become breezy in the afternoon in a
tightening surface gradient as a surface trough approaches from the

A cold front will slide through the area early on Sunday, though the
coldest air will lag behind the initial frontal passage with highs
still into the 30s to lower 40s. The much colder air plunges into
the area on Sunday night with temperatures falling into the single
digits and teens overnight. Accumulating snow is still looking like
a good bet for Sunday night with decent frontal forcing as a
shortwave tracks across the area. Still uncertainty on amounts with
model differences (and it should be noted that the 00z European model (ecmwf)
continues a more northward trend, keeping the higher quantitative precipitation forecast for the
most part north of our cwa), but consensus would place the highest
amounts north of Interstate 90, with 2 to 4 inches of accumulation
possible as very cold air will result in efficient/high snow ratios.
In coordination with surrounding offices, blended wpc guidance into
the given nbm quantitative precipitation forecast for Sunday night as it was much too light.

Any snow looks to pull east of the area on Monday morning, but winds
will pick up in a strong cold air advection regime, and this could
result in some blowing snow in parts of the area. Increased winds
over given nbm guidance which was too light. Highs on Monday will
only be in the teens to lower 20s, though wind chills will generally
be below zero.

The theme for the remainder of next week will be for much below
normal temperatures as an upper level trough deepens over the
central and eastern Continental U.S. Into midweek. The coldest days will be
Tuesday and Wednesday with highs only in the single digits and
teens, with lows on Tuesday night from near zero to 10 below. By the
end of the week, we begin to see some recovery as the upper level
flow flattens out. The amount of warming will depend on how quickly
this happens - with some model differences - but may rebound into
the 20s and 30s by Friday of next week. Precipitation chances look
to be minimal through the week.


Aviation...(for the 18z tafs through 18z Saturday afternoon)
issued at 1222 PM CST Fri Dec 6 2019

Widespread MVFR to upper IFR ceilings in place from along and east
of kbkx-kfsd-kslb line, with the battle between erosion from the
east and advection of the layer from the west. Areas between the
James River and I-29 likely to be slowest to break ceilings, as
erosion continues from the west/south and east, especially for
those areas from khon eastward to kmds/kbkx.

A lot of questions remain whether more widespread lower clouds
will attempt to redevelop below the strengthening inversion
tonight and Saturday morning. Confidence not high enough to put
in, but with shallow nature to moist layer, did hint at potential
with some MVFR visibility at taf locations.

Any low level wind shear looks to be fairly brief, a couple or three hours mid to
late evening until around midnight, and did not mention at this
time in most likely areas for kfsd/ksux.


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


National Weather Service Glossary of Abbreviations