557 
FXUS63 KFSD 072038
AFDFSD

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
238 PM CST Sun Nov 7 2021

.SHORT TERM...(This Evening through Monday)
Issued at 231 PM CST Sun Nov 7 2021

Upper level cirrus, combined with poor seasonal sun angle, has kept 
temperatures a off the pace compared to yesterday's but most 
locations ending up at least 10-15 degrees above normal for 
afternoon highs today with very mild conditions across NC Neb/SC
SD currently.

Meanwhile, a wave moving west to east north of the International 
border is dragging a somewhat diffuse cold front across the region 
with winds turning out of a more westerly then northerly 
direction behind it. Not expecting any precip with the surface 
feature overnight with overnight lows a few degrees either side of
40. 

What may provide for some precipitation chances for Monday is a vort 
max running underneath the upper level jet streak that will help to 
induce/strengthen an area of roughly 700 mb frontogenesis from west 
central to northeast SD. Decent consensus in guidance that this 
narrow corridor of rain or rain/snow mix stays to the northwest of 
our coverage area but a handful of ensemble members and even a few 
high-res models drop this as far south as a Chamberlain to Huron to 
Brookings line. A quick glance of the 18z shows a similar
southward shift compared to its 12 counterpart. For now, have 
introduced some small POPs and sprinkle/flurry mention but
additional modifications may be needed.

Persistent CAA courtesy of a northerly surface wind will keep 
temperatures closer too (albeit a shade above) normal values or 50s 
to near 60. 

.LONG TERM...(Monday Night through Sunday)
Issued at 231 PM CST Sun Nov 7 2021

Somewhat better clustering around yesterday's ECMWF solution 
advertising another transient shortwave cutting above the surface 
high pressure on Tuesday with associated light QPF. Forecast 
soundings show a relatively dry subcloud layer so again expect 
minimal impact if any precip can actually reach the surface although 
may see another period of increased mid/upper cloud cover. 

Wednesday into Friday continues to be the most interesting part of 
the forecast period as upper level troughing digs into the central 
US eventually establishing a cut off low across the Northern Plains 
by late Thursday into Friday. Still plenty of questions about the 
finer details of this system but here's a few things that appear 
possible for our immediate area. First, rain chances look to 
increase Wednesday as initial bout of trough axis associated 
precipitation swings through the region. Second, as the surface low 
begins to deepen towards anomalous values to our east, the SPG really 
begins to tighten on its western flank providing for gusty winds 
later Thursday into Friday. Have raised these wind values as the 
populated NBM was in the lower quartile of guidance. Finally, a 
fairly broad area of wrap around precipitation is expected to 
straddle the I-29 corridor through the Northern Plains Thursday 
night into Friday with the eventual pivot point of the previously 
mentioned surface low determining how far north/south and east/west 
this precipitation area reaches. This is of particular importance as 
an influx of cold air means much, if not all of this precipitation 
will fall in the form of snow. This potential combination of falling 
snow and gusty winds will be a forecast feature to monitor across 
the broader region going forward. Its important to note that the 
ensemble envelop remains quite wide with vastly varying levels of 
concern. Temperatures are likely to fall below normal through the 
second half of the week with perhaps 30s for highs by Friday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1040 AM CST Sun Nov 7 2021

Periods of upper level cirrus will continue with winds becoming
more westerly and then northerly through the second half of the
day as a front passes. Will likely see a second increase in
mid and upper level clouds for Monday morning with some low end
precipitation chances around KHON. 

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...Kalin
LONG TERM...Kalin
AVIATION...Kalin