textproduct: Sioux Falls

KEY MESSAGES

- Periods of scattered showers with isolated thunderstorms will spread north today, mainly along/east of Highway 81. Mostly light accumulations expected.

- Elevated to locally near critical fire concerns are expected by Sunday as unseasonable warmth returns along with breezy westerly winds. This along with critical RH values (18%-30%) will lead to high to very high fire danger with the focus being from south-central South Dakota to southwest Minnesota.

- Renewed chances for showers and storms return on Monday and Tuesday with the potential for a few stronger storms. However, some details remain uncertain.

UPDATE

Issued at 422 AM CDT Sat Apr 11 2026

Early morning ACCAS (spotty high-based showers and a few storms) developed around 1 AM. This has continued to bubble and lift slowly northeast in a broad warm advection regime. Have updated early morning precip chances to account for this activity.

An additional surge of warm advection is seen in some high-res guidance through mid-morning. Beginning to see this development in northeast Nebraska, and CAMs are consistent in showing this activity expand in coverage as it lifts north this morning before weakening/moving east of the forecast area by midday. While a few high-based storms are again possible, severe weather is not expected.

SPC has maintained a Marginal (Level 1 of 5) risk for severe storms across southeast portions of our forecast area in the latest Day 1 (today and tonight) and Day 2 (Sunday-Sunday night) outlooks. For Day 1, the primary concern would be an isolated strong to severe storm in northwest Iowa as the low level jet increases later this evening into the overnight hours. While a couple of the more robust high-res models depict a stronger storm developing, the majority of the CAMs lack much more than a lingering drizzle potential from widespread stratus, with marginal mid- level lapse rates and generally weak deep layer shear limiting severe potential tonight.

For Day 2, storm development during peak heating/instability depends on timing of a modest shortwave sliding across the area. Latest models bring the wave through in the morning to midday which could suppress activity as we move through the afternoon. If the timing of this wave is delayed, instability is sufficient to support a few storms, though deep layer shear is on the weak side, so overall severe threat is still uncertain.

As indicated in the Day 3 outlook, Monday afternoon-evening would bring the more favorable set-up for some strong to severe storms, with another mid-level wave sliding east atop a warm front lifting north through Iowa and Minnesota. Still some variance among models in placement of better instability and shear, so please monitor the forecast through the weekend for the latest updates.

DISCUSSION

Issued at 230 PM CDT Fri Apr 10 2026

It's a fairly pleasant and sunny Friday afternoon across the area! Changes are on the way though; it will get warmer... but also a bit stormier. Warm air advection (WAA) increases tonight, helping to bring some showers into the area early Saturday morning. These showers will move into the Missouri River Valley at first and lift northeastward into Saturday morning. A few rumbles of thunder will be possible with this activity, but severe weather is not expected. With the return of southerly flow and cloud cover associated with the aforementioned showers, expect a much milder night tonight with lows in the upper 30s to low 40s.

Warm air advection showers will be ongoing Saturday morning especially east of I-29. These showers will push off to our east into north central Iowa and south central Minnesota through the early afternoon. Saturday will be warmer and breezy, but with showers around and increasing moisture due to continued southerly flow, the fire weather danger will be low. The only place where we could see elevated fire weather concerns Saturday afternoon would be over south central South Dakota where clouds decrease the quickest and thus it will be a bit warmer out that way. Off to our west, an upper wave will be moving across the Rockies and sending impulses our way. Additional showers and storms may develop overnight Saturday into Sunday as the low level jet strengthens, allowing for around 1000-1500 J/kg of instability to move across the area. Any storms will be elevated given the capped low levels, leading to large hail up to the size of quarters as the main threat if a storm can become severe. The better chances of an isolated severe storm will be over northwest Iowa early Sunday morning, right where the Storm Prediction has the area in a Level 1 out of 5 Marginal risk for severe weather.

A shortwave trough will move across the northern Plains on Sunday and in response, a low pressure system will move across the Red River Valley into southern Canada. West-southewesterly flow will return to area in the wake of this system and bring a punch of much drier air into the area, especially west of I-29. This is where relative humidity (RH) values will drop below 30%, with RH values as low as 18-20% possible in south central South Dakota. It will be breezy and warm, with wind gusts around 30 mph and highs into the 80s. All this will lead to elevated to potentially critical fire weather concerns for areas west of I-29, so Sunday will be a day to avoid outdoor burning. Winds look to decrease through the late afternoon, so this could limit the extent of the fire weather threat into Sunday evening, but keep in mind it will still be dry and warm.

The active weather pattern continues into Monday as a deep trough over the central West Coast begins to move eastward. Monday looks to have the better chances for severe weather compared to Sunday morning, though uncertainty remains especially with the location of storm development. The 10.12Z ECMWF has storms developing over our area, while the 10.12Z runs of the NAM and RRFS have storms not developing until east of the area. This is at least in part due to timing and placement differences in the position of a surface low, with the ECMWF slower with this and the NAM and RRFS being faster. These finer details will need to be ironed out before we could start looking into individual severe threats, though a slower solution would favor surface based storms while a faster solution would favor elevated thunderstorms. The parent trough will eject across the area on Tuesday, and this could potentially lead to another threat of stronger storms as yet another low pressure system moves across the region. A few showers may linger into Wednesday, but models diverge significantly from there. With no big pushes of cold air advection following any of these systems, we look to remain warm into much of next week with highs possibly staying the 70s even into Wednesday and Thursday of next week.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 653 AM CDT Sat Apr 11 2026

MVFR to IFR conditions will expand north-northeast across the forecast area this morning, accompanied by scattered high-based showers and perhaps a few isolated thunderstorms. Potential for thunder is too low to include at KFSD, but a little better at KSUX so did include TS in a PROB30 group early in the TAF period. Also a remote chance for an isolated storm developing around KSUX late this evening, so included a brief window of potential there as well, though confidence is lower than the chances this morning.

IFR or even LIFR ceilings may be accompanied by MVFR-locally IFR visibility in fog and/or drizzle this afternoon into tonight.

Southeast to south winds will occasionally gust 25-30kt into the early evening, with gust potential waning after sunset as the boundary layer stabilizes within the lowering stratus layer. In the absence of gusts, a southerly low level jet will produce a period of low level wind shear late evening through the end of the TAF period.

FSD WATCHES/WARNINGS/ADVISORIES

SD...None. MN...None. IA...None. NE...None.