522
FXUS63 KFSD 171215
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
615 AM CST Mon Nov 17 2025

.KEY MESSAGES...

- An early winter system will bring periods of rain/drizzle,
  snow, and potentially a little sleet this afternoon into
  Tuesday morning. Precipitation amounts and the potential for
  accumulating snow have increased north of I-90, especially in
  in parts of east central South Dakota and southern Minnesota.

- Moderate to locally high (50-80+%) probability of rainfall (or
  liquid equivalent of snow) exceeding 0.50 inch northeast of a
  line from Huron-Sioux Falls-Spencer Iowa.

- A trend toward cooler nighttime temperatures has increased
  the potential for snowfall of 1-2 inches in higher elevations
  of southwest Minnesota, with moderate (40-60%) probability of
  localized snowfall greater than 2 inches northeast of a
  Brookings to Windom line.

- Late week system has trended slightly southward, but still low
  (20-30%) rain chances as far north as Sioux City-Storm Lake on
  Friday.

&&

.DISCUSSION...
Issued at 350 AM CST Mon Nov 17 2025

TODAY-TUESDAY MORNING: Forecast track and timing of a compact
early winter system largely remains on track. However, latest
high-res models have trended higher on overall precipitation
amounts north of the storm track, as well as a little more
aggressive on cooling the thermal profile in response to the
band of strong lift north of I-90 tonight. As such, we are
looking at greater potential for accumulating snow for portions
of east central South Dakota and southwest Minnesota tonight
into the morning commute time on Tuesday.

TIMING: Storm system currently moving across the central Rockies
will develop into a compact mid-upper level low as it moves east
across Nebraska/southern South Dakota through this evening and
into the Upper Mississippi Valley tonight. While the system will
initially be fighting some dry low level air, expect saturation
to quickly work downward in response to the increasing lift by
early this afternoon. This should result in a rapid increase in
rain coverage through the afternoon, especially along and north
of I-90 near a strengthening mid-level front, while southern
areas begin to see a mid-level dry slot work northward.

A relatively narrow band of moderate to heavy precipitation
looks to persist through the evening and overnight hours,
lingering in southwest Minnesota through the morning commute
hours before sliding off to the east.

LOCATION/AMOUNTS: While the location could still wobble a bit
north/south, the latest consensus places this band north of a
Huron-Sioux Falls-Spencer Iowa line, more favored in locations
near to just north of the Highway 14 corridor around and east of
Brookings. 00Z HREF probabilities for greater than 0.50 inch of
liquid precipitation (rain or liquid equivalent of snow) have
increased dramatically in this area over the 12Z run for the
period ending at 12Z/6 AM CST Tuesday, with a moderate (40-60%)
probability as far south as Sioux Falls to Spencer, and high
(80+%) near to north of the Highway 14 corridor. The NBM has
likewise begun to capture the higher precipitation amounts and
we are now seeing a growing potential for amounts up to an inch
of liquid in portions of east central SD/southwest Minnesota
through Tuesday morning. Amounts will taper sharply southwest
of the Huron-Sioux Falls-Spencer line, with less than 0.10"
expected through the Missouri River Valley.

PRECIPITATION TYPE: Temperatures will peak in the mid 40s to
around 50 around midday, then begin to fall as rain increases
through the afternoon. Some areas north of I-90 could fall back
into the upper 30s by sunset. Most areas should see only rain
through sunset and even into the early evening, though higher
precip intensity could lead to pockets of sleet/snow at times in
the late afternoon to early evening.

Increasing dew points will limit how quickly temperatures drop
off this evening and ultimately how low they fall by daybreak
Tuesday. However, the latest models have trended a little bit
cooler, especially within the precipitation band across our
north where strong lift aids in dynamic cooling of the column.
This will allow for greater accumulation of snow from late this
evening into Tuesday morning, mainly from east central SD into
southern Minnesota. Snowfall should still have some elevation
dependency as well, with locations along the Buffalo Ridge in
southwest Minnesota more likely to see an inch or two of snow,
perhaps locally higher, by daybreak. Meanwhile, lower elevation
areas to the east of the ridge (Marshall-Tracy) are more likely
to see less than an inch of slushy accumulation. It should be
noted that this is still the lowest confidence portion of the
forecast, as just a degree or two warmer/colder could result in
significant changes to snowfall location and amounts. Continue
to monitor the forecast throughout the day for the latest
updates.

TUESDAY AFTERNOON-WEDNESDAY: Lingering clouds and/or fresh
snowfall will lead to a chilly Tuesday with highs from the mid
to upper 30s in southwest MN to mid 40s through the Missouri
River Valley. Warmer air briefly builds into the area Wednesday
with 50s becoming more prevalent, though any lingering snow
cover in southwest Minnesota could hold readings in the 40s.

THURSDAY ONWARD: The late week system seems to have trended a
bit farther to the south as it tracks east through the central
Plains. Most of our area currently looks to remain dry, with low
(20-30%) chances for light rain largely confined to areas from
Sioux City to Storm Lake. Could see a brief cool-down Friday
with northerly flow behind the departing wave, but otherwise
temperatures look to remain near to above seasonal normals into
next weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 615 AM CST Mon Nov 17 2025

VFR conditions to start the period this morning, but
deteriorating conditions are expected from midday onward as a
quick moving storm system slides across the area. Lowering
ceilings will lead to increasing coverage of rain and/or drizzle
this afternoon and evening, with an area of snow developing from
east central South Dakota into southern Minnesota. IFR-locally
LIFR visibility in snow will be possible in areas from KBKX-KMML
to perhaps as far south as KTKC-KMWM after 04Z-06Z tonight.

While impacts from snow are expected to be minimal at our TAF
locations, MVFR to IFR ceilings and/or visibility in drizzle/fog
will dominate the latter half of the TAF period.

&&

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

&&

$$

DISCUSSION...JH
AVIATION...JH