textproduct: Sioux Falls

KEY MESSAGES

- Isolated to scattered showers this morning will become more widespread and continue for the rest of the day. Light accumulations are expected with up to a 0.10" of an inch or two possible through tonight.

- Additional shower and thunderstorm chances (50%-80%) are expected over the weekend with the potential for a few stronger storms from Saturday night into Sunday. The main concerns will be damaging winds up to 60 mph and locally heavy rainfall.

- Low chances (<=30-40%) for rain will persist through the bulk of next week. However, severe storm chances continue to look low (5%) through next week.

UPDATE

Issued at 508 AM CDT Fri May 29 2026

Taking a look across the area, we're continuing to monitor areas of developing showers lifting out of northeastern NE this morning. However, with lingering dry air in the lower levels according to soundings, most of this activity is currently struggling to reach the ground. Nonetheless, we're still on track for precipitation coverage to gradually expand eastwards around daybreak as a mid- level wave continues to progress through the area and low-level moisture advects into the region with strengthening southeasterly surface winds. From here, expect a rinse and repeat for the rest of the day with pockets of intermittent showers lifting through the area keeping conditions on the drearier side.

With increasing precipitation chances and persistent cloud cover expected, decided to taper highs down across areas west of I-29 for the day. This resulted in highs in the low to mid 70s across southcentral SD and upper 70s to low 80s everywhere else. Lastly, could see a brief transition to drizzle this evening as we lose mid- level saturation. However, we could also an uptick in shower and thunderstorm development from early saturday morning (4-5 am) onward across the Missouri River Valley as the Nocturnal LLJ strengthens. While severe weather is not expected, stronger updrafts could produce small hail and locally heavy rainfall.

DISCUSSION

Issued at 222 PM CDT Thu May 28 2026

High level cirrus continues to blanket the area early this afternoon. There is enough heating to result in some spotty showers for the rest of the afternoon and early evening timeframe though. Some rumbles of thunder and perhaps a few gusts up to 30-40 mph could accompany the showers. Like yesterday, these showers will be diurnally driven and will cease as the boundary layer stabilizes by sunset. However, rain chances will not be done yet as a diffuse upper level low currently over the central Plains will slowly push into the area this evening and night. This will bring more stratiform precipitation to the area with the potential for a rumble or two of thunder mainly for locations along and north of the Missouri River and west of I-29. The clouds and rain will keep low temperatures on the warm side, only falling to the upper 50s and 60s.

Friday is looking to be cooler than previously thought as this same system will take its time meandering through the forecast area. A few convective showers to weak thunderstorms are possible on its front edge where slightly less cloud cover and slightly higher instability will be present. But with the rain in the area, high temperatures will only warm to the 70s to low 80s, making for a warm but dreary day. On top of the rain, southeast winds will be strengthening in response to as the surface pressure gradient tightens across the area. Gusts up to 15-35 mph is expected, with the strongest winds occurring along and west of the James River. Latest guidance is suggesting that saturation in the dendritic growth zone (DGZ) could become offset from the better low level saturation. This looks to potentially lead to some drizzle in locations that are not saturated aloft. Chances (40-60%) for rain will persist through the overnight hours. Low temperatures will fall to the 50s overnight. Rainfall through this period of time looks to be light ranging from a few hundredths to a few tenths.

The next chance for isolated strong to severe storms will come on Saturday as an upper level trough grazes the western fringes of the area. Broad southeast flow will advect higher moisture into central Nebraska and central/western South Dakota. Deep layer shear will remain weak at about 20 knots. Instability however looks to potentially (40-80% chance) exceed 1,000 J/kg across parts of south central South Dakota. Warm air advection (WAA) in conjunction with shortwave troughs rotating through the base of the upper level trough will provide forcing for ascent. Some questions remain as to whether the instability can overcome the weaker deep layer shear and where the warm sector sets up. For now, think a conditional risk for strong to severe storms is on the table. Rain chances look to continue through the night and on Sunday as well. Severe weather chances are questionable on Sunday as well since the main upper level trough's vort max will be advected well northwest of the area. Steeper mid level lapse rates may also result in a large cap aloft. For now, the ensembles show a broad 40-60% chance for rainfall totals to exceed a tenth of an inch on Sunday. Will keep an eye on this potential over the next few days. Total rainfall amounts look to reach up to and possibly exceeding a half an inch by the end of the weekend. The highest totals look to fall across central and south central South Dakota. The amount and location of heaviest rain can still change over the coming days depending on how showers and storms shake out. Aside from rain chances, the weekend will see breezy southeasterly winds with high temperatures warming to the upper 70s to low 80s.

The omega block pattern looks to persist into early next week. Medium range guidance depicts the omega block beginning to break down by the middle of next week. For the Northern Plains, it looks like zonal flow will take over. This pattern change will still keep rain chances in the forecast as broad southerly flow will advect sufficient moisture into the area. The ensembles show 30-40% chance or less for rainfall exceeding a tenth of an inch through the bulk of next week. Questions remain regarding whether or not vertical shear will be strong enough to support strong to severe storms. This uncertainty is nicely shown in the latest machine learning (ML) guidance as all of the ML models show a 5% chance or less for severe storms. Aside from rain and storm chances, high temperatures look to remain warm in the 80s.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 635 AM CDT Fri May 29 2026

Mainly VFR conditions will transition to a mix of MVFR to IFR and lower this TAF period. Taking a look at radar, lots of virga on radar right mainly due to drier air in the lower levels. Should see things saturate by mid to late morning leading to scattered showers at all TAF sites at times. Decided to go prevailing since coverage should be widespread. Might have a brief break this evening as we lose mid-level saturation. However, could get additional redevelopment by early Saturday morning with a strengthening nocturnal LLJ. As a result, added in PROB30s for both KFSD & KSUX for the increased probabilities towards the end of the period. Lastly, MVFR to IFR (and potentially LIFR) cigs will gradually spread eastwards overnight leading to continuous dreary conditions.

FSD WATCHES/WARNINGS/ADVISORIES

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