Spencer, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

704
FXUS63 KFSD 061050
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
550 AM CDT Sun Jul 6 2025

.KEY MESSAGES...

- Scattered showers and storms will be possible today, mainly
  west of the James River Valley. The risk of severe storms is
  low.

- Greater potential for scattered thunderstorms late Monday into
  Monday night. Some of these storms could be severe, especially
  west of US Highway 81 through the evening where a Level 2 of 5
  risk for severe storms is in place. Hail up to golf ball size
  and wind gusts to 70 mph are the primary threats.

- Additional storms are again possible later Thursday into
  Friday. While details are uncertain, a few strong to severe
  storms may develop, so continue to monitor your local forecast
  for updates.

- Seasonal high temperatures in the upper 70s and 80s are expected
  through Tuesday, with highs in the 90s briefly returning to some
  areas west of I-29 midweek.

&&

.DISCUSSION...
Issued at 355 AM CDT Sun Jul 6 2025

TODAY-TONIGHT: First wave of storms which were robust as they
moved through western SD early in this overnight period have
weakened substantially and are not expected to bring much of an
impact to our far western counties. A trailing area of storms
which has redeveloped over the High Plains of western SD are
likewise projected to move east through the early-mid morning.
Expectation is for this activity to similarly weaken as it moves
across the Missouri River, but will hang onto lower end chance
pops in our far western counties to cover the potential. Another
seasonably cool day today with highs in the upper 70s to mid 80s,
but less humid as dew points briefly drop into the upper 50s to
mid 60s.

For tonight, will have to monitor track of a wave induced by late
day storms which are expected to develop over western Nebraska. If
the wave tracks far enough north, it could bring some nighttime
showers/storms to the Missouri River Valley/Highway 20 corridor
into Monday morning. Greater consensus leans toward keeping this
activity south of our area, but will carry some low (20-30%) pops
for now.

MONDAY-MONDAY NIGHT: Aforementioned low pops for our far southern
counties will linger into Monday afternoon, but focus primarily
shifts to a stronger wave and associated boundary dropping into
central-northeast South Dakota by mid-late afternoon. While exact
timing/location of initiation is uncertain, confidence is fairly
high that we will see scattered storms develop along the boundary
in the mid afternoon, with ample instability (>1500J/kg) and deep
layer shear (35-40kt) supporting initially discrete severe storms
capable of large hail and perhaps an isolated tornado. While the
location differs, CAMs are in generally good agreement that the
storms will rather quickly transition into bowing line segments
which will track southeast into the evening. Primary threat will
evolve into damaging wind gusts up to 70 mph, with embedded QLCS
tornadoes possible. Activity should weaken as it tracks farther
east, with primary threat window from around 4pm through midnight.

TUESDAY-THURSDAY: As the Monday trough moves east, a modest mid to
upper level ridge builds over the Rockies/High Plains. This will
allow warmer air to build back into at least our western counties
with highs pushing back into the lower 90s by Wednesday-Thursday.
Aside from a potential for storms lingering in northwest Iowa into
Tuesday, the midweek period looks primarily dry. However, this
may depend on subtle waves which drift through the weak flow
aloft, with some solutions bringing showers/storms back to the
area by Wednesday night-Thursday.

THURSDAY NIGHT-SATURDAY: A stronger wave breaks down the ridge
by late Thursday with a northern stream wave digging into the
northern Plains Thursday night-Friday. While the chance for
showers/storms should increase, potential for severe storms is
uncertain at this range, with ensembles indicating low (<30%)
probabilities for sufficient shear to support organized severe
storms. However, various machine learning/AI solutions highlight
probabilities for severe on Thursday-Thursday night in portions of
the northern Plains, as does the latest Day 5 outlook from SPC,
so this late week period will merit watching for those with
outdoor plans.

Temperatures behind this wave do cool more substantially, with
highs in the 70s to lower 80s more probable for the end of this
week.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 550 AM CDT Sun Jul 6 2025

VFR conditions through the period. Very low chances for light
showers or a stray thunderstorm approaching the James River Valley
(KHON) today, and the Highway 20 corridor (KSUX) tonight. However,
confidence is too low to mention.

Light northerly winds today become variable to light easterly
tonight.

&&

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

&&

$$

DISCUSSION...JH
AVIATION...JH