textproduct: Sioux Falls

KEY MESSAGES

- Critical fire weather concerns continue through Tuesday evening. Use extreme caution when working or spending time outdoors.

- Critical fire weather may return again Thursday as winds gust above 40 mph, along with a risk for isolated to scattered thunderstorms. Severe storms are not expected.

- Temperatures continue to warm though the weekend, with high temperatures expected to be 10 to 20 degrees above normal.

- Regional rain chances increase Saturday and especially Sunday. A great deal of uncertainty remains, but a few signals present for strong storms late Sunday.

DISCUSSION

Issued at 1239 PM CDT Tue May 12 2026

THIS AFTERNOON: Hot, dry, and windy conditions which have been the story of much of May, continue this afternoon. We'll continue to see gusts 35 to 45 mph at times this afternoon as relative humidity continues to fall into the 20 percent range. Some reports this afternoon of blowing dust from farm fields, so will include patchy mention in the forecast until wind relax.

TONIGHT: Winds gradually relax this evening, turning light and variable into Wednesday morning as the surface ridge of high pressure slides southeast. With temperatures in the 40s, no frost concerns.

WEDNESDAY: Winds remain light and variable into early afternoon before a steady increase in southerly winds across central Nebraska/South Dakota by late afternoon. High temperatures rise through the 70s and may reach the 80s near the MO river valley.

THURSDAY: A mid-lvl ridge axis will slide east Wednesday night, pushing east of I-29 by daybreak Thursday. Models continue to show signals for low-lvl moisture convergence by daybreak Thursday which could spark elevated showers and a few thunderstorms moving eastward into the afternoon. MUCAPE remains limited AOA 700 J/KG, so not anticipating severe weather. Further west, a frontal boundary forms in central South Dakota and become a potential focal point for surface based convection late in the afternoon. Dew points ahead of the boundary may only reach the low 50s, but the increase in synoptic lift and steepening lapse rates may support an isolated storm or two marching eastward in the evening. Winds and fire weather may be the bigger story during the day as NBM probabilities for wind gusts over 40 mph surpass 70% by mid-day. Should dew points mix into the lower 40s, then RH may fall near 25% at times, leading to critical fire danger. Fire weather watches may be needed if forecast conditions remain as currently projected. One alternative scenario to watch is a stalled area of mid-lvl clouds east of I-29 that could temper the rise of temperatures in the afternoon and keep fire weather danger in check.

FRIDAY: A stronger frontal boundary pushes southeast by daybreak Friday, lowering dew pints and bringing slightly cooler northwesterly surface winds into the area. Another dry day with low RH is anticipated.

SATURDAY-MONDAY: There remains quite a bit of model discrepancy heading into the upcoming weekend, focusing on precipitation chances as well as severe weather risks. By Saturday morning we'll begin to see some influence of broadening southwesterly mid-lvl flow and slowly increasing moisture return. First likely in the form of increased cloud cover, but then by increasing PoPs Saturday night. Sunday poses considerably more uncertainty as Mid-lvl flow tries to turn more southerly and results in stronger poleward return flow. The latest LREF 24 hour POP over 0.10" has continued to increase on Sunday, as high as 60-70% in some locations but especially focused along and east of I-29. The high probabilities of lower totals followed by lower probabilities of higher totals (>0.50") would signal agreement in the risk for rain, but minimal agreement in where meaningful rain might develop. Severe weather risks also remain very uncertain especially given uncertainty in just how far north the warm sector may lift. Conditional probabilities would suggest greatest potential is focused south of I-90, and this is supported by the AI-learning outlook products. Temperatures this weekend will be highly dependent on cloud cover and rain, but there remains potential for highs to climb into the 80s. A cold front sweeps southeast on Monday, lowering temperatures for the new work week.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1203 PM CDT Tue May 12 2026

VFR conditions with gusty northwest winds continue into the evening. Winds gradually weaken and turn light and variable by daybreak Wednesday.

FIRE WEATHER

Issued at 1239 PM CDT Tue May 12 2026

Latest observations continue to show RFW criteria building through the forecast area Tuesday afternoon. Wind gusts will rise into the 30 to 40 mph range into early evening as relative humidity values fall in the 20 to 25% range.

Thursday will be another potential critical fire danger day as southwesterly gusts increase quickly in the morning, gusting over 40 mph at times into the afternoon. While relative humidity values will be slightly higher, any further mix-down in afternoon dew points could push values to critical thresholds. One concern in the forecast may be morning scattered showers that could linger into the afternoon potentially impacting temperature forecasts and lowering risks slightly. This will need to be monitored in future forecasts.

FSD WATCHES/WARNINGS/ADVISORIES

SD...Red Flag Warning until 9 PM CDT this evening for SDZ038>040- 050-052>071. MN...Red Flag Warning until 9 PM CDT this evening for MNZ071-072- 080-081-089-090-097-098. IA...Red Flag Warning until 9 PM CDT this evening for IAZ001>003- 012>014-020>022-031-032. NE...Red Flag Warning until 9 PM CDT this evening for NEZ013-014.