textproduct: Sioux Falls

KEY MESSAGES

- Isolated sprinkles to showers are possible this afternoon. Confidence in occurrence and coverage is low (< 20%).

- Additional shower and thunderstorm chances (50%-80%) return by Tuesday. Stronger storms Tuesday afternoon and evening may be capable of producing large hail and strong winds. However, uncertainty remains regarding severe storm potential. - Below normal temperatures continue through mid week before more seasonable temperatures return from late week into the weekend. Periodic shower and storm chances continue as well.

UPDATE

Issued at 251 AM CDT Mon Jun 22 2026

Isolated sprinkles and patchy drizzle continue to diminish across southeastern SD into the southern MO River Valley this morning. Beginning to see some patchy fog develop with light winds and clearing skies near US Highway 14, although scattered stratus and more widespread mid clouds may prevent widespread fog. Expect clouds to clear somewhat late morning before diurnally driven cumulus develop. Can't entirely rule out an isolated sprinkle but have omitted mention with scant moisture both in the unstable layer and sub cloud layer. Highs in the upper 60s to upper 70s.

Shower and storm chances return late tonight west of I-29 as the next wave ejects east. CAMs are quite varied on how quickly convection races out of the Black Hills, and lower res deterministic guidance remains quite varied on the timing of the mid/upper level forcing. Shower and storm chances continue through the day Tuesday and into Tuesday night as surface cold front and another mid/upper trough swing through the area. A few storms Tuesday and into Tuesday evening could be strong to severe; however, uncertainty remains due to timing issues and cascade effects of any morning convection (how strong the AM storms might be, how much do we recover later in the day, etc). Main threat with any stronger storm would be hail to half dollar size and wind gusts to 60 mph. Main forecast change was to edit pops through Tuesday evening to better fit some of the latest trends.

DISCUSSION

Issued at 208 PM CDT Sun Jun 21 2026

CURRENTS & TONIGHT: A dreary day continues! Taking a look across the area, we're continuing to watch areas high-based showers and drizzle progress through portions of the area this afternoon. While we're still on track for this intermittent activity to continue through early evening, we're starting to see an influx of drier air via water vapor satellite imagery lift into the area which could gradually erode at this activity over the next few hours. If this continues to hold true, things could taper down rather quickly with most activity becoming focused across southcentral SD into the evening. From here, we'll probably continue to have spotty showers across portions of southcentral SD and the Missouri River Valley through Monday morning as the surface low stalls out across northcentral NE and gradually weakens. Otherwise, another cool night will be on tap as lows decrease into the low to mid 50s.

MONDAY & TUESDAY: Looking into the early week, could still have a few spotty showers to start the day on Monday mainly across southcentral SD. While accumulations will be light, could see coverage expand in the early afternoon as a weak wave moves through the area and a couple hundred Jules of instability develop above the mixed layer. Nonetheless, should see this spotty activity gradually diminish after sunset as we lose diurnal heating. By Tuesday, additional shower and thunderstorm chances (50%-80%) are expected as a cold front progresses through the area. However, the severe weather risk looks more uncertain than yesterday. Still a wide range of solutions as far as how things could evolute during the day. With this in mind, this is probably the reason why our friends at SPC just blanketed most of our area in a Day 3 Marginal (Level 1 of 5). Nonetheless, another high shear/low CAPE environment will make for at least a marginal risk for large hail and damaging winds along and ahead of the surface front. Won't know many additional details up until guidance latches on a solution though. Lastly, temperatures will continue to hover near to just below normal with highs mainly in the low to mid 70s on both Monday and Tuesday.

WEDNESDAY ONWARDS: Heading into the midweek, quieter conditions should return for Wednesday and Thursday as a surface high tracks through our area. From here, the wave train returns by Friday as quasi-zonal flow helps usher in multiple shortwaves increasing the chances from showers and potentially thunderstorms almost daily (every 24-36 hours) into the following week. While the chances for severe weather are still uncertain at this time, this is another period that will need to be monitored closely moving forward. Lastly, we'll start to see temperatures build towards more seasonal conditions with highs increasing from the low to mid 70s on Wednesday to the low to mid 80s by Saturday.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1143 AM CDT Mon Jun 22 2026

Scattered afternoon CU field continue to develop. Soundings suggest a very small amount of instability, which may allow upscale growth to small showers or very isolated thunderstorms. Further west, a persist overcast cloud layer will continue along and west of the James River.

By tonight, scattered convection over western SD/NE will begin to slide east, weakening to showers and very isolated thunderstorms as it moves into the CWA by daybreak. This rain will move east slowly in the morning bringing low probabilities for MVFR conditions by mid-late morning.

FSD WATCHES/WARNINGS/ADVISORIES

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