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fxus63 kfsd 171716 

Area forecast discussion
National Weather Service Sioux Falls South Dakota
1116 am CST sun Nov 17 2019

Short term...(today through monday)
issued at 400 am CST sun Nov 17 2019

At 09z, stretching trough pushing through the area with the leading
band of light rainfall left to clear northwest Iowa over the next 2-
3h. Quite expansive stratus behind the trough back through central
South Dakota and will be a feature of the day across most of the area. As a
result of the clouds and cold advection, temperatures won't have far
to go today most locations based on mixing potential. Exception
could be west of the James River where clearing could begin early
enough in the afternoon to salvage a greater potential mixing. The
challenge will be the narrowing potential clearing wedge, as the
next mid-level warm advection should spill appreciable high clouds
back toward south central South Dakota by late afternoon. Temps would appear
to be capable of near 40 in southwest Minnesota, gradually moderating to
near 50 toward south central South Dakota. In this case, something closer to
the median solution or even a bit on the lower side for the eastern
half appears appropriate given the clouds.

The next weak wave in northwest flow will zip southeast into
northern plains tonight, and be near eastern South Dakota by daybreak Monday.
European model (ecmwf) is just a bit more diggy with the wave, keeping track more
westward of the frontal features. While it again will be working to
saturate the profile downward from mid-levels as broad warm
advection works to warm the lower to mid portions of the sounding,
locating the boundary will be most important to the precip
distribution. Overall, the structure of the system is ragged, and
precipitation should be largely tied to the most concentrated band
of warm advection by later tonight and into Monday morning. Should
be mainly near/west of the I-29 corridor by late night, and then
spreading south/east Monday morning before ending. Href is about as
solid on precip chances as any guidance, and actually brings a bit
higher concern for some spotty light icing. Will have temps rising
with the lower clouds/warming lower profiles, and maxtw aloft is
likely a bit too cool given the expected lighter precip rates. While
all looks to fall as liquid, will be the surface temps that
determine type. Still appears as if there could be a brief period
for locations east of I-29 to see a bit of light freezing rain
potential, but even if this occurs, temps should be near to a bit
above freezing not far removed from onset. Therefore, impacts likely
would be minimal, but worthy of watching in case one or more of the
involved elements evolves differently.

Clouds will linger until evening east of I-29, with transition to
clearing near I-29 likely just after sunset. Therefore, temps east
will struggle somewhat in the 40s, while the areas toward the James
River and west will be free to see some lower to mid 50s. Still,
above normal for all looks fairly likely.

Long term...(monday night through saturday)
issued at 400 am CST sun Nov 17 2019

Ridging aloft builds for Tuesday, with lowering pressure into the
Western Plains and development of a warm frontal zone near the
Missouri River. The southern areas near the river are most likely to
have potential for warming, with several solutions in the 75th to
90th percentile into the upper 50s, and some actually near 60
degrees. Much will depend on mixing and getting a little better
mechanical gradient in place, as otherwise could see a zone of
fairly weak surface winds within the deformation zone with the
frontal boundary. Will also have increasing higher clouds by later
day spreading in from the west. Settled with a 50-75th percentile
forecast across the areas north of I-90, trending toward 90th
percentile in the Missouri River valley.

Trough splitting over the western Continental U.S. Will leave the area in the
confluence by Wednesday. This will gradually drive a sharpening
trough/front eastward. Still plenty of warming near/ahead of the
feature, but most moisture through the day will be increasing in a
fairly shallow near-surface layer, suggesting perhaps more of a
stratus/drizzle potential instead of actual rainfall. Heading
through Wednesday night, approaching wave in the southern branch
will head into the confluence zone over the area. Trend has been for
the European model (ecmwf) solution to shift strongly toward the earlier GFS,
producing a banded area of precipitation over the southern half of
the area, with temperatures dropping enough to transition from rain
to snow overnight. Some accumulations are likely with the current
iteration of solutions, ending fairly rapidly on Thursday as the
system zips through the confluence and the more dominant northern
branch drives cooler and drier air southward.

The remainder of the forecast period looks quiet into the upcoming
weekend, with temps near normal.


Aviation...(for the 18z tafs through 18z Monday afternoon)
issued at 1112 am CST sun Nov 17 2019

Widespread MVFR ceilings will slowly start to erode later this
afternoon and evening. Breaks in the clouds will be relatively
short lived as the next system works in late overnight and into
Monday morning. This will bring the chance of very light
precipitation with primarily rain as the precipitation type at the
3 taf terminals. Locations east of I-29, mainly SW Minnesota, carry a
small chance of having a brief window of freezing rain although confidence
is low. Ceilings will likely lower back toward/into the MVFR range
for a period late in the taf period.


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


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