textproduct: Sioux Falls

KEY MESSAGES

- Scattered light showers and perhaps an isolated thunderstorm drift southeast, dissipating during the Thursday morning commute. Additional scattered light showers/isolated thunderstorms are possible with peak heating again Thursday afternoon-early evening.

- Patchy to areas of frost may be possible Friday and Saturday morning. Temperatures will be highly dependent on cloud cover both nights.

- Temperatures will warm above normal by the upcoming weekend into early next week.

UPDATE

Issued at 337 AM CDT Thu Apr 30 2026

Watching showers move southeast over the forecast area this morning as a mid level wave tracks through the area. Have refined pops slightly to account for current trends. Although chances remain low, can't rule out an isolated rumble or two of thunder as soundings continue to show some weak elevated instability. Showers are still expected to exit the area around daybreak.

No significant changes to the forecast, with another mid level wave aiding in the development of diurnally driven showers and isolated thunderstorms this afternoon and evening. Thunder risk continues to be low due to the weak instability aloft. Rainfall amounts are expected to be light. Highs warm into the 50s. Showers taper off through the late evening as we lose diurnal heating. Still some questions regarding frost potential tonight into Friday morning as guidance does show clouds over most of the area through the night, which may keep temperatures a touch warmer.

No changes to Friday, with some guidance still producing isolated showers in the far eastern portion of the forecast area. Currently, guidance shows less cloud cover around the area for Friday night/Saturday morning, which would lead to more efficient radiational cooling and frost. Will keep an eye on trends, and those with sensitive vegetation outdoors should keep an eye on the forecast as well.

DISCUSSION

Issued at 104 PM CDT Wed Apr 29 2026

THIS AFTERNOON: Diurnal CU already forming early this afternoon, which could eventually lead to a few sprinkles over NW Iowa and SW Minnesota. An additional area of weak warm advection aloft has developed high based showers and isolated thunderstorms along the James River. However, more focus for showers and isolated storms will arrive later this afternoon and continue into the evening as a shortwave slides southeast. Soundings show 100-500 J/KG MLCAPE through the afternoon and evening hours, suggesting a few thunderstorms develop. Steep low-lvl lapse rates could promote the transport of 30-40 mph gusts in any stronger shower. Would also not be surprised to see some small hail especially west of the James River.

TONIGHT: CAMS all hint that synoptically drive showers may continue to move southeast through the overnight hours. More clustering of showers may develop around a compact area of vorticity tracking through the Tri-State area. Have increased PoPs as a result of reasonable modeling of this potential. Temperatures will fall overnight, but cloud cover will pose the greatest hindrance to any widespread frost or freeze conditions.

THURSDAY-FRIDAY: The second in a series of three shortwave rotating around a broad upper trough will arrive on Thursday. Similar to today, we'll see rapid destabilization ahead of the wave leading to scattered showers and isolated thunderstorms in the afternoon and early evening. Low-lvl temps are even a bit cooler than today, so some graupel could be possible. The third and final wave rotating through the region is progged to move into the region early Friday morning. This wave could hold onto enough low-mid lvl cloud cover to keep temperatures from falling below freezing, though with light winds any break in clouds may result in frost to near freeze conditions. Cooler northerly flow under surface high pressure will lead to quiet weather on Friday. Though again, afternoon CU will likely fill the sky. Highs remain in the middle to upper 50s.

SATURDAY-SUNDAY: As we've been discussing the past days, we'll begin to see warmer temperatures arrive this weekend, but remain in a pattern that suggests a frontal boundary sliding through the region every 1-2 days. This results in a great Saturday, with southwesterly surface winds and highs in the middle to upper 60s. Model clustering supports the passage of a cold front early on Sunday. High temperatures once suggested to be in the upper 70s a few days ago, will likely only reach into the middle to upper 60s. The passage of this front may not result in any more than sprinkles early Sunday morning.

MONDAY-TUESDAY: This aforementioned pattern continues into the middle of the week suggesting temperatures remain near to slightly above normal, with precipitation chances surrounding a frontal passage late Tuesday growing to near 30 percent in LREF and NBM guidance.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 619 AM CDT Thu Apr 30 2026

This morning's showers stretch from KYKN to near KMWM, and continue to move southeast. An isolated rumble of thunder remains a low risk. This activity is expected to dissipate through the morning commute. Additional scattered showers and possibly an isolated thunderstorm are expected this afternoon through the evening hours. Left mention out of KSUX for now, with lower confidence in coverage this evening toward US Hwy 20.

Wind gusts today top out around 20 knots, although some showers this morning have briefly produced gusts around 25 knots. VFR conditions prevail through much of the period, although some MVFR/IFR conditions are possible (and have been observed) with heavier showers.

FSD WATCHES/WARNINGS/ADVISORIES

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