textproduct: Sioux Falls

KEY MESSAGES

- Elevated fire danger this afternoon and evening across south central South Dakota with humidity below 20% and west wind gusts around 20 mph.

- Thunderstorms return this afternoon and evening. Scattered strong to severe storms expected - greatest risk for southwestern Minnesota into adjacent areas of South Dakota and Iowa. Timing of greatest concern is 4 to 10 PM.

- Main hazards are large hail to 2 inches in diameter and wind gusts to 70 mph. A tornado or two are also possible. Have a severe weather plan and multiple ways to receive warnings.

- Periodic chances (20-60%) for showers and thunderstorms continue this week. Details remain uncertain at this time.

UPDATE

Issued at 330 AM CDT Mon Apr 13 2026

Area of showers and isolated storms continues to move northeast out of NE this morning. So far, have only seen a couple of sprinkles on area DOT and partner cameras, and soundings show a dry sub cloud layer so not surprised to see limited precipitation this morning. Expect these to continue with WAA/wave. Watching stratus and fog drop south along the MN/SD border to US Hwy 14 as well, reducing visibility. Patchy radiation fog is developing across northwestern IA where skies are clear, which has dropped some visibility to less than 2 miles. Finally, watching what appears to be the warm front lift north of I-90 on radar, which will be a catalyst for storms later today.

Although the main focus of the forecast remains on the severe weather potential later today, do need to mention the elevated fire concerns across south central SD this afternoon/evening with minimum humidity values below 20%. Limiting factor for widespread or significant concern is the wind - with gusts around 20 mph.

Main focus of the forecast remains on the severe weather potential later today and through this evening. Forecast is generally on track from yesterday and earlier updates. Biggest question continues to be where the surface warm front is going to set up and the resultant dry line and triple point are located. Variance on the warm front still ranges from the I-90 corridor to near/north of the US Hwy 14 corridor. Some question if any of the morning showers/storms and cloud cover may impact warming and therefore instability later and if so - where with CAMs still showing a couple different areas of development and quite varied on the location of both areas. Surface low and supporting mid/upper waves are both still progged to move out of NE into our forecast area by early to mid afternoon (2-4 PM) with the mid/upper wave slightly lagged, likely leading to the CAMs showing 2 areas of development. Ample shear and steep lapse rates lead to large 2 inch hail as the main hazard, with damaging wind gusts to 70 mph. With the warm front in play and the potential for supercells, a tornado or two cannot be ruled out. Initial development of supercells may grow upscale with the 0-6km shear somewhat parallel to the warm front. Keep an eye on the forecast today and stay weather aware.

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 10 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 /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1235 AM CDT Mon Apr 13 2026

VFR conditions are expected for the majority of the period. Winds will be light and variable through daybreak. There is a 30-40% chance of patchy fog development tonight focused over the Buffalo Ridge in southwest Minnesota, and northwest Iowa including KSUX. Visibility may drop to less than 2 miles at times. Fog is expected to burn off by mid-morning.

A few light sprinkles to rain showers are possible over central South Dakota early Monday morning, moving northeast through about daybreak. Confidence in showers forming is low due to a substantial dry subcloud layer, so have left them out at this time. As the day continues chances for thunderstorms increase (30-60%) for areas along and north of I-90, to include KFSD and KHON. A few of these storms could be strong to severe producing large hail (2+ inches) and wind gusts up to 70 mph. Though chances are low a tornado or two cannot be ruled out. Timing of storms is most likely between 13.21Z and 14.04Z. Storms push clear of the region shortly after.

FSD WATCHES/WARNINGS/ADVISORIES

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