Storm Lake, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

474
FXUS63 KFSD 120337
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1037 PM CDT Mon Aug 11 2025

.KEY MESSAGES...

- Areas of wildfire smoke across far eastern South Dakota,
  southwest Minnesota, and northwest Iowa will drift eastward
  this evening, resulting in improving air quality.

- A weak cold front will drift southward this evening and
  overnight, resulting in a 20-30 percent chance for showers and
  thunderstorms along and north of the Highway 14 corridor. The
  risk for severe weather is low.

- There is a 30 to 50 percent chance for showers and thunderstorms
  Wednesday night. A few thunderstorms may become strong to
  severe.

- Higher heat and humidity return Thursday into the weekend when
  afternoon heat index values could approach 100 degrees,
  especially south of I-90. There is also additional chances for
  showers and thunderstorms during this period (20-40 percent).

&&

.DISCUSSION...
Issued at 254 PM CDT Mon Aug 11 2025

1930Z satellite imagery, combined with surface observations,
show lingering wildfire smoke along and east of a line from
roughly Brookings to Yankton. Visibility is these areas is as
low as 3 to 5 miles. HRRR smoke model shows this area drifting
eastward late this afternoon and evening, resulting in improved
visibility and air quality.

Later this evening, a short-wave trough moves along the Canadian
border with an attendant surface cold front draped southwestward
into southwest MN and southeast SD. Latest guidance suggests
some showers and thunderstorms may develop along this boundary,
primarily impacting the Hwy 14 corridor and points north.
Despite modest instability, the best deep layer forcing remains
north of the forecast area, so the severe weather threat is low.

Surface high pressure builds across the region Tuesday, resulting
in dry, mostly sunny conditions. Temperatures will also be a
bit cooler as tonight`s frontal passage ushers in a slightly
cooler air mass. Expect afternoon highs in the upper 70s to
lowers 80s.

High pressure drifts eastward Wednesday with low pressure
developing along the lee of the Rockies in response to a short-
wave undercutting the 500 hPa ridge across the southern Canadian
Prairies. This allows for southerly return flow and increasing
moisture. As this wave moves across the Dakotas/Minnesota, look
for increasing shower and thunderstorm chances Wednesday night.
While the forecast area isn`t currently outlooked for severe
weather, instability/shear may support a few stronger to severe
storms.

Thursday into the weekend, the primary focus will be increasing
heat and humidity as a 500 hPa ridge tries to reassert itself
across the southern/central Plains. A return of temperatures in
the mid 80s to mid 90s and dewpoints in the upper 60s to mid 70s
could result in some heat index values approaching 100 degrees,
especially south of I-90. Quasi-zonal flow aloft during this
period may allow embedded short-waves to move across the region,
increasing the threat for showers and storms. Not enough
confidence in the mesoscale details at this time to go above the
NBM`s 20-40 percent POPs.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1035 PM CDT Mon Aug 11 2025

Wildfire smoke will continue to pull slowly eastward out of the
area tonight. A frontal boundary will push southeastward across
the area, and this will bring scattered showers and isolated
thunderstorms to areas mainly through the Highway 14 corridor
and northward. Winds will transition to northwesterly with the
passage of the front. With light winds residing over northwest
IA later tonight, there will a 30-50% probability for patchy fog
over that area through Tuesday morning. VFR conditions are
expected to prevail through the remainder of the TAF period.

&&

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

&&

$$

DISCUSSION...Rogers
AVIATION...JM