Spencer, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

214
FXUS63 KFSD 151743
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1143 AM CST Mon Dec 15 2025

.KEY MESSAGES...

- Quieter conditions with mild temperatures Monday-Wednesday,
  though fresh snowpack may limit how quickly temperatures
  initially warm.

- Wednesday afternoon into Thursday will bring the next system
  with the potential for impacts across the area. More of a
  strong wind threat than significant snow. However, if more
  than flurries accompany the cold surge, blowing snow could be
  more impactful as winds potentially gust to around 50 mph.

- Cooldown with mid-week system will be brief, with seasonably
  mild temperatures returning Friday into the weekend.

&&

.DISCUSSION...
Issued at 258 AM CST Mon Dec 15 2025

TODAY-WEDNESDAY: The coldest air has moved off to the east and
our pre-dawn temperatures have climbed into the mid teens to mid
20s. Mild temperatures will be around for the next 2-3 days as
broad upper ridging transitions to a quasi-zonal flow through
the first half of the week. Already seeing temperatures near to
slightly above freezing in south central SD as of 2 AM, a sign
of things to come with highs today expected to range from near
freezing east of I-29 to lower-mid 40s in south central SD. That
said, NBM shows a 5-10F spread between 10th/90th percentiles of
its members. This is a little broader range than we typically
see for Day 1, indicating some uncertainty how much the snowpack
will impact highs today. That said, HREF mean is within 1-2F of
the NBM so did not stray from the ensemble means at this point.

After a slight evening cool-down, warm advection tonight ahead
of a weak wave will result in steady to rising temperatures
after midnight, with breezy southwest winds gusting to 25-30
mph expected along and east of the Buffalo Ridge in southwest
Minnesota. HREF probabilities are hinting at some fog potential
tonight, but with the rising temperatures and increasing wind
overnight, do not expect anything widespread.

Mild westerly low level flow Tuesday will continue to eat away
at the snowpack, as even surface dew points are expected to
climb above freezing by Tuesday afternoon. This could lead to
a better chance for areas of fog developing Tuesday night as
winds drop off with a passing surface ridge and we`ll have
another day of snowmelt moisture added to the boundary layer.

The aforementioned wave will have little moisture to work with
this far south, so precipitation is not expected with its
passage late Tuesday/Tuesday evening. Cooling also looks to be
negligible as the coldest post-frontal air slides off to our
north/northeast. Highs both Tuesday and Wednesday will generally
range from upper 30s-lower 40s east to some 50s in south-central
SD, though again some uncertainty, depending on how quickly the
snow melts, or if fog/low clouds do develop Tuesday night and
persist into Wednesday.

WEDNESDAY NIGHT-THURSDAY: A strengthening wave digs into the
northern Plains. While there are some differences in timing of
the cold front, general thinking points to Wednesday night
remaining rather mild, especially across the southeast half of
the CWA, while northwest areas could see sharper cooling already
by daybreak Thursday. Low level cooling continues through the
day Thursday, with steady to falling temperatures expected in
some areas. Greatest impact for our area with this system still
looks to be strong post-frontal winds late Wednesday night into
Thursday morning. NBM shows moderate (40-60%) probability of
advisory level gusts exceeding 45 MPH, but some indications that
this may be on the low side. Deterministic model soundings show
50+kt winds atop the mixed layer, which would support higher
gusts 55-60+ MPH in some areas near/west of I-29 as seen in the
NBM 90th percentile for early Thursday. With the uncertainty in
frontal timing, did not alter the NBM just yet. Will monitor
trends and adjustments may be needed if confidence in timing
increases.

Fortunately, the preceding warm air will make any lingering
snow on the ground unblowable, and the track of the system
keeps significant snow chances on the low side in our area.
However, some solutions produce a few hundredths of QPF in the
cold post-frontal air mass. With the anticipated strong winds,
accumulating snow could become more impactful due to additional
blowing snow concerns and this will be closely watched in the
coming days. For now, those with travel plans should at least be
prepared for the strong winds and perhaps occasional flurries.

FRIDAY ONWARD: The cool-down on Thursday looks to be short-lived
as mild air quickly returns to the region Friday. Additional
weak waves slide through the region this weekend. Precipitation
chances are low due to limited moisture and weekend temperatures
will likely be cooler than Friday but not cold for this time of
year.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1141 AM CST Mon Dec 15 2025

Mainly VFR through the period. There will be some fog potential
mainly east of the James River into parts of southwest MN and
northwest IA late tonight into early Tuesday morning. Will
include some fog mention in these areas.

&&

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

&&

$$

DISCUSSION...JH
AVIATION...08