textproduct: Sioux Falls

KEY MESSAGES

- Elevated to critical fire danger will persist through the rest of this afternoon before ending this evening. A Red Flag Warning remains in effect for locations along and west of highway-75 until 7 pm.

- Strong to severe storms are possible tomorrow. Some uncertainty remains but locations along and near highway-14 from Brookings, South Dakota to Marshall, Minnesota have the highest chances for seeing strong to severe storms. The main timeframe for severe weather is between 3 pm to 9 pm Monday. Continue to check the forecast for the most up to date information.

- Chances (20-60%) for showers and storms look to persist through the rest of the week. Details remain uncertain at this time.

DISCUSSION

Issued at 243 PM CDT Sun Apr 12 2026

Fire danger persists this afternoon along and west of I-29. More details can be found in the fire weather discussion below. Breezy westerly winds persist with high temperatures warming to the 70s to low 80s, making for a warm April day. Fire danger will come to an end this evening as temperatures cool and winds weaken. Low temperatures will fall to the upper 40s and 50s overnight.

Winds will turn to out of the south/southeast on Monday, resulting in moist southerly flow and moistening dew points back into the 40s, 50s, and even low 60s. High temperatures will warm to the upper 70s and 80s across the area as a warm front pushes northwards. There remains uncertainty in where the warm front sets up. Some of the latest hi-res models bring the warm front to the vicinity of highway- 14. Some push the front just north of the highway while others are just south. This will have a big effect on any severe storm potential during the afternoon hours tomorrow. A stout elevated mixed layer (EML) will be in place. Sounding climatology would place this EML at the very top of climatology for this time of year! This EML will result in capping across the warm sector, limiting more widespread convective coverage. It could completely prohibit any storms from developing across the area though again that depends on where the warm front sets up. This uncertainty also extends to the location of the surface low tied to the warm front. Latest ensembles are in line with the latest hi-res guidance in lifting the surface low through the center of the forecast area. This would then turn surface winds to out of the west both within and behind the low. The westerly winds will advect much drier air into the area. This drier area will make for a much narrower warm sector with the best instability residing just along the warm front itself where moisture is still able to pool. CAPE values look to reach up to 1500 to 2000+ J/kg along the front in tandem with more than sufficient vertical shear in place thanks for an upper level jet sitting over the area. As of now, the best convergence along the warm front is along highway-14 from Brookings, South Dakota to Marshall, Minnesota. This looks to be the main area for convective development as sufficient low level moistening and convergence looks to be just enough to overcome the cap. Should storms develop, it looks to be a smaller number of storms, only about 1 to 3 storms. Thus, large hail up to 2 inches in diameter, 70 mph winds, and an isolated tornado is possible. The main timeframe for convection would be between 3 pm to 9 pm.

Tuesday will be a quieter day as Monday's boundary will be pushed off to the southeast. This will keep any instability along with strong to severe storm chances out of the area. However, there remains the potential for some light rain if a deformation zone can set up. Though if it does, any rainfall would be light at a tenth of an inch or less. Tuesday will also be slightly cooler with high temperatures in the upper 60s to upper 70s.

Chances for strong to severe storms look to continue through the rest of the week. Wednesday could be the next chance for severe weather as medium range guidance shows another wave pushing through the area. These models do show that this wave may close off which could bring a warm front further north, thus bringing more instability with it. As of now, the ensembles show the low staying south and east of the forecast area. Will still keep an eye on trends over the coming days in case the low comes north. As of now, high temperatures look to warm to the upper 60s to low 70s.

Thursday looks to be a quiet day as shortwave ridging pushes through the Plains. A stronger upper level wave looks to eject into the Plains on Friday. A stronger cold front will be tied to this wave. Severe storms could be possible along this front though currently medium range guidance shows the cold front either just about to fully pushing through the forecast area by Friday evening. This could preclude severe weather chances if the front pushes through the forecast area quickly. Something to keep an eye on as we progress through the week. Chances for precipitation could continue through Saturday before dry conditions return for Sunday.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1221 PM CDT Sun Apr 12 2026

VFR conditions begin the TAF period. Some high level cirrus is present across parts of northwest Iowa early this afternoon. Mainly clear skies is expected to continue for the rest of the daylight hours. Winds remain westerly with gusts up to 20-30 knots. These winds are expected to weaken through the rest of the afternoon timeframe. Light winds will persist for the overnight hours. There is a low potential (20-40% chance) for low level stratus or fog to develop late tonight into tomorrow morning. This stratus/fog potential is highest across northwest Iowa, including KSUX. Have left out of KSUX's TAF at this time due to low confidence but will keep an eye on trends. Winds will turn southeasterly to end the TAF period.

FIRE WEATHER

Issued at 243 PM CDT Sun Apr 12 2026

Temperatures have warmed to the 70s to low 80s across the area. Dew points have lowered to the mid 30s to 40s across the majority of the area. The exception is locations across northwest Iowa and parts of southwest Minnesota where dew points have remained in the 50s to about 60F. Thus, humidity values have fallen to about 20-30% across the majority of the forecast area, excluding northwest Iowa and parts of southwest Minnesota. Winds remain westerly with gusts continuing to remain above 30 mph. Thus, critical fire danger conditions have been met. Have expanded the Red Flag Warning another row of counties north and east to account for the rest of the fire danger. The Red Flag Warning remain in effect until 7 pm this evening when cooling temperatures and weakening winds will end the fire danger.

Elevated fire danger remains possible tomorrow as low humidity is expected along the Missouri River Valley. However, winds will be much lighter as they turn from southeasterly to westerly with gusts only up to 15 to 25 mph. Thus, only high fire danger is expected.

FSD WATCHES/WARNINGS/ADVISORIES

SD...Red Flag Warning until 7 PM CDT this evening for SDZ050- 052>071. MN...Red Flag Warning until 7 PM CDT this evening for MNZ097-098. IA...Red Flag Warning until 7 PM CDT this evening for IAZ001-012- 020. NE...Red Flag Warning until 7 PM CDT this evening for NEZ013-014.