Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kfsd 191126 
afdfsd

Area forecast discussion
National Weather Service Sioux Falls South Dakota
526 am CST Tue Nov 19 2019

Short term...(today and tonight)
issued at 300 am CST Tue Nov 19 2019

Seasonably mild temperatures continue today, with a fair amount of
sunshine after some passing early morning mid-high clouds across
the southwest portions of the forecast area, and perhaps some
stratus scraping the northeast. Winds will be on the light side
thanks to a surface ridge moving across the region, so this may
limit mixing a bit, but should still see highs in the mid 40s to
lower 50s most areas.

Tonight will see broad warm advection across the region, which
should lead to some increase in mid-high clouds, and a mild night
overall with lows in the 30s.

Long term...(wednesday through monday)
issued at 300 am CST Tue Nov 19 2019

Wednesday-Thursday will be the primary focus this forecast period,
as a broad shortwave ejects out of a deep western Continental U.S. Trough, and
lifts northeast through the mid-Missouri Valley. Currently seeing
pretty good agreement on the track of the wave and associated
surface low, the latter of which develops over the Central High
plains Wednesday afternoon, then tracks northeast through western
Iowa Wednesday night, and into eastern Wisconsin by midday Thursday.
This is a wet system for this time of year, with operational GFS/NAM
as well as gefs mean indicating nearly an inch of precipitable water
spreading into northwest Iowa Wednesday night. This is above the
99th percentile of climatology for this time of year, or +2 to +3
Standard deviations above the climatological mean. Fortunately (for
non-snow lovers, at least), this moisture will fall mostly as rain
Wednesday night, as surface and low level temperatures remain above
freezing through much of the night. Overall looking at a potential
for a half inch to an inch of precipitation along and southeast of
the Minnesota/Iowa Highway 60 corridor, with amounts tapering to around a
tenth of an inch in our northwest counties. Timing of the influx of
colder air will ultimately determine snowfall amounts, but right
now, looking for amounts to remain less than an inch, possibly
approaching an inch in higher elevations of east central South Dakota into
southwest Minnesota and south central South Dakota.

The NAM is slightly fast outlier with the timing of the cold air,
and is also farther north with a secondary band of precipitation
late Wednesday night into Thursday morning. If this were to pan out,
may be looking at increased snowfall amounts from far southeast South Dakota
into southwest Minnesota. However, with the progressive nature of the wave,
and limited mid-level frontogenesis to focus this secondary heavier
band, will stick with consensus for now.

In the wake of this system, temperatures will revert to below normal
again, but only briefly as warming is expected again by late in the
weekend and into early next week. Dry weather is expected to prevail
through the end of this forecast period on Monday.

&&

Aviation...(for the 12z tafs through 12z Wednesday morning)
issued at 525 am CST Tue Nov 19 2019

MVFR ceilings may slide through parts of east central South Dakota and
southwest Minnesota today, but are expected to remain east of our taf
sites. Otherwise VFR conditions are expected to prevail through
this taf period, with a potential for areas of MVFR conditions in
southwest Minnesota again late, after 20/09z.

&&

Fsd watches/warnings/advisories...
South Dakota...none.
Minnesota...none.
Iowa...none.
NE...none.
&&

$$

National Weather Service Glossary of Abbreviations