textproduct: Sioux Falls

KEY MESSAGES

- Periods of scattered showers with isolated thunderstorms continue into the overnight hours. An isolated strong to severe storm is possible along and east of Iowa/Minnesota Highway 60 between 4 am and 7 am. Large hail to the size of a half dollar (1.25") is possible.

- Strong northwest winds are expected Wednesday with gusts of 45 to 55 mph. A Wind Advisory will be in effect for the entire area from 10 am to 9 pm on Wednesday. Another round of isolated to scattered showers could result slightly higher wind gusts (to 60 mph) during the afternoon.

- The next potential chance for strong to severe storms could return on Saturday. Specific details are uncertain but as of now, the highest probabilities for severe storms remains south and west of the area.

UPDATE

Issued at 902 PM CDT Tue Jun 16 2026

No significant changes to the forecast through the next 12-18 hours. Scattered showers and isolated thunderstorms continue to move southeast across the northern Plains this evening. Lightning at the time of this discussion remains across ND where the better synoptic forcing is (via the mid/upper jet). The mid/upper jet and trough axis continues to move southeast through the overnight hours, with showers and isolated storms lingering as well. Severe weather risk remains low through the early overnight hours as storms move into our less favorable environment, especially west of I-29. Could maybe still see a rogue stronger gust - most CAMs now keep stronger gusts around 40-45 knots (45-50 mph) instead of 50 knots (58 mph).

As we head toward 4 AM CDT and later, guidance continues to show increasing moisture and instability in response to the WAA and increasing LLJ along and east of IA/MN State Hwy 60. Any storms that could develop (or restrengthen from earlier in the overnight) could produce hail to half dollars is possible. Storms early Wednesday morning will have to overcome a bit of a cap even if we see instability increase to around 500 J/kg. Shear and lapse rates are both supportive of large hail through 7-8 AM CDT.

Wind Advisory remains in good shape as strengthening CAA and compressed surface pressure gradient lead to wind gusts to 55 mph across the area through the day.

DISCUSSION

Issued at 226 PM CDT Tue Jun 16 2026

Starting to see some echoes on radar begin to move into the forecast area from central South Dakota this afternoon as we begin to see an upper level wave push into the Northern Plains. With dry air in the low levels, little if any rain will reach the surface. Could see an isolated wind gust up to 30-40 mph as the showers push through. The main forcing from the wave will come during the overnight hours which will increase the coverage of showers and some storms. Latest hi-res guidance shows a strengthening low level jet (LLJ) that will bring a small elevated moist layer northwards. This moist layer will push into locations around highway-60 eastwards. This will be a brief window where weak elevated instability on the order of about 300 to 500 J/kg of CAPE can be generated and support the potential for an isolated severe storm. The timeframe is between 4 am to 7 am. Large hail up to quarter size is possible. These showers will continue to push off to the southeast and begin exiting the area through tomorrow morning.

A cold front will push through the area early Wednesday morning. A strong push of cold air advection (CAA) will accompany the cold front. Despite the CAA, highs look to warm to the 70s and 80s. The main impact from the CAA will be strong northwest winds. Winds will gust up to 45-55 mph Wednesday afternoon across the entire area. As such, a Wind Advisory has been issued for the entire forecast area from 10 am to 9 pm. Another round of isolated to scattered showers is on the table as well for Wednesday afternoon. Isolated higher wind gusts are possible within these showers. Elevated fire danger is possible across south central South Dakota where the humidity will be lowest. The shower activity will be waning through the evening along with the strong wind gusts.

Thursday and Friday will be relatively quieter days with high pressure pushing through the area. High temperatures will warm to the 70s and 80s. A few showers are possible on both days but otherwise the days should largely be dry. Low temperatures will fall to the upper 40s, 50s, and low 60s. The warmest lows will come Friday night.

Upper level troughing will be pushing eastwards on Saturday, putting the right entrance region over the forecast area. This looks to bring a warm front near the Missouri River valley. Medium range guidance has the surface warm front south and west of the forecast area. The ensembles also support this as they also show the surface front residing south and west of the forecast area. The vast majority of machine learning guidance (ML) further supports this conclusion as well. That said, this is the surface front location. Can't rule out the potential for elevated storms though it is too far out to say for sure if the elevated boundary may make it to near the Missouri River Valley. The ensembles also show the highest probabilities (60-80%) for rainfall amounts exceeding a tenth of an inch south and west of the Missouri River as well. Aside from storm chances, Saturday looks to be a near seasonable day with highs in the upper 70s and 80s.

Zonal flow looks to take over for Sunday and Monday. This could result in additional chances for rain but this remains uncertain due to the variance in shortwave troughs evolution among the medium range guidance. The ensembles reflect this uncertainty as they only show a 20-40% chance for rainfall amounts to exceed a tenth of an inch on both days. Otherwise temperatures look to remain near seasonable in the 70s.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 628 PM CDT Tue Jun 16 2026

Mostly VFR conditions through the period, although MVFR and briefly lower conditions are possible with showers and thunderstorms. Scattered showers and very isolated thunderstorms continue to stream in from the northwest tonight, with additional showers/thunderstorms possible Wednesday afternoon. Have limited mention to PROB30 groups at all sites, and excluded TSRA mention for tonight given some uncertainty in coverage of precip.

LLJ strengthens overnight, which could lead to some LLWS for much of the area. However, omitted mention as speed shear is below criteria with the anticipated gusts overnight, although directional shear at times could be around 40-60 degrees. Otherwise, surface wind direction through the overnight will be a bit variable between east and south, with gusts around 20 knots. Winds Wednesday morning shift northwesterly and quickly strengthen with gusts around 35-40+ knots through much of the day.

FSD WATCHES/WARNINGS/ADVISORIES

SD...Wind Advisory from 1 PM to 9 PM CDT Wednesday for SDZ040-056- 062-067-071. Wind Advisory from 10 AM to 9 PM CDT Wednesday for SDZ038-039- 050-052>055-057>061-063>066-068>070. MN...Wind Advisory from 1 PM to 9 PM CDT Wednesday for MNZ071-072- 080-081-089-090-097-098. IA...Wind Advisory from 1 PM to 9 PM CDT Wednesday for IAZ001>003- 012>014-020>022-031-032. NE...Wind Advisory from 1 PM to 9 PM CDT Wednesday for NEZ014. Wind Advisory from 10 AM to 9 PM CDT Wednesday for NEZ013.