164
FXUS63 KFSD 031132
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
532 AM CST Tue Mar 3 2026

.KEY MESSAGES...

- Drizzle and fog have expanded this morning, leading to reduced
  visibility Temperatures are largely remaining above freezing,
  mitigating any large scale icing potential, but could see
  slick spots for the morning commute.

- Confidence is high in another extended period of well-above
  normal temperatures through the weekend.

- Confidence also remains higher than normal in returning rain
  risks Thursday into Friday during the passage of a front. A
  few rumbles of thunder are possible, especially across
  northwestern Iowa.

- Precipitation amounts for the end of the week are still
  favored to remain low, with current probabilities of over
  0.50" less than 40%. However, this may mark the most
  significant precipitation chance we`ve had for some time.

&&

.UPDATE...
Issued at 531 AM CST Tue Mar 3 2026

Drizzle and fog have expanded with low stratus over the area early
this morning. Most visibility in our forecast area has remained
above a mile, although watching fog across the central MO River
Valley north of Chamberlain, where visibilities have dropped at or
below half a mile. Most of the area remains just above freezing,
outside of a few sites in southwestern MN. This should limit
widespread icing issues, but can`t rule out some patchy slick spots
for the morning commute. Conditions should improve through the mid
to late morning.

&&

.DISCUSSION...
Issued at 1221 PM CST Mon Mar 2 2026

THIS Afternoon: Stratus continues over portions of IA/MN and far
eastern SD this afternoon, though satellite suggests the cloud layer
is quite thin. Temperatures have again risen into the 40s in
most areas, cooler over the deeper snow pack from the weekend
snow. Further west, we`re seeing the development of light
showers in the West River and Panhandle areas. This light rain
will continue on an eastward path late this afternoon, but will
be fighting a very pronounced dry layer centered around 850mb.

TONIGHT:  Light rain/sprinkles will continue to move eastward
through the evening hours tied to a stronger vort lobe along I-90.
After the passage of this wave, soundings suggest that we`ll lose
ice in the atmospheric column, and with the continuation of very
weak isentropic lift AOB 800mb we may begin to see drizzle develop
into daybreak Tuesday. There remains some fluctuation in overnight
temperature potential. Assuming we can warm into the upper 30s to
lower 40s, expanding stratus after dark may help blanket the area
and keep temperatures a few degrees above freezing and mitigate any
icing potential. The deterministic NBM seems to be biased by the
recent cold overnight periods with hourlies at or below the 25th
percentile.  With that said, have blended in more short term CAMs
that keep hourlies near or just above freezing in most areas.
Confidence remains high that QPF itself will be very light, with
only a 30% probability of more than 0.10". Most may see only a
couple hundredths.

TUESDAY:  We`ll continue to remain under the influence of mid-lvl
vorticity into mid-day Tuesday, while the introduction of a light
northerly wind AOA 800 mb should lessen the depth of the low-lvl
moisture layer and gradually reduce the drizzle production potential
south of I-90.  Temperatures warm into the upper 40s to 50s in the
afternoon.  An upper trough will eject slowly eastward into the Mid-
Missouri River valley Tuesday night and Wednesday, with weak
channeling of low-lvl moisture and weak warm advection back to areas
south of I-90 and towards Highway 20 overnight.  This will continue
or reintroduce the potential for drizzle to spits of rain into
Wednesday morning. With temperatures again above freezing no impacts
are likely.

WEDNESDAY: Mid-lvl heights begin to rise on Wednesday, and surface
winds turn back to the south through the day.  A thermal ridge will
develop over the Dakotas and point towards the Arrowhead of
Minnesota by Wednesday afternoon. Temperatures at the surface
respond by jumping into the 60s west of the James River and 50s to
the east.

THURSDAY-FRIDAY: Medium range models and their ensembles remain in
strong agreement for the end of the week, pushing a long wave
trough over the West Coast Wednesday into the Plains by Thursday
and Friday. Closer to home, the initial response will be deeper
lee- side troughing Thursday which will allow the thermal ridge
to slide east, but also increase the southerly surface winds.
While the airmass ahead of this trough is warm, ESAT tables
would suggest that this airmass sits around the 90th percentile
of climatology centered around early March. Meaning, at this
point, the potential for records remains low Thursday and
Friday. One thing to watch is the potential for any stratus to
linger along or east of I-29, which would have a lowering impact
on temperatures.

Regarding precipitation, this is where some slight deviations in
guidance develop.  Both EC/GFS/CMC show the potential for the long
wave trough to split, with a positively tilted trough sagging
eastwards into Friday, and energy at the base of the trough diving
southward.  This split, while uncertain, could deviate the moisture
trajectory of this system. On the other hand, some guidance
(mostly EC but some GFS members) does bring a more condensed
area of vorticity northeastward, allowing at least some moisture
and instability (~300-500 J/KG MUCAPE) to focus near the Tri-
State area. The potential release of this instability may be
the one key aspect of the forecast that could drive up QPF
potential, which based on other ensemble solutions remains low.
Probabilities of >0.1" have risen to near 80%, with
probabilities of >0.50" much lower at 20- 30%. No matter what,
this system does at least have the potential of producing more
than a ground wetting rain by time it ends late Friday. This
system also has hints of a separate deformation band trying to
form over central SD that could turn into a rain/snow mixture
depending on timing.

SATURDAY-MONDAY: Temperatures remain very warm heading into next
weekend with no strong cold advection behind the passing trough
Friday. Breezy southwesterly winds are likely next weekend, but
especially on Saturday where the SPG increases quickly.
Temperatures in the 50s and 60s are expected, with the current
NBM forecast sitting closer to the 75th percentile of the
ensemble solutions.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 531 AM CST Tue Mar 3 2026

Low stratus, fog, and drizzle have expanded over the area this
morning, leading to widespread MVFR to IFR conditions with isolated
LIFR ceilings and visibility. Fog and drizzle should diminish
through the morning hours. Most areas outside of southwestern MN
remain above freezing, which should limit any widespread freezing
drizzle or freezing fog.

Conditions should improve through the day; however, have gone a bit
more pessimistic at KFSD and KSUX with slower improvement and
most of the period with MVFR or lower conditions, as guidance
continues to show low stratus today and again tonight.
Confidence is lower than average on the exact timing and
category, but feel the trends are better reflected in this
issuance.

Winds through the period remain light and variable.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.

&&

$$

UPDATE...SG
DISCUSSION...Dux
AVIATION...SG