textproduct: Sioux Falls

KEY MESSAGES

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

- Friday now also seeing the potential for critical to near critical fire weather conditions, especially near and north of I-90.

- 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.

UPDATE

Issued at 244 AM CDT Wed May 13 2026

The challenge in reaching critical fire conditions for Thursday appears to be a extensive cloud cover in the east along with the potential for scattered showers and isolated thunderstorms. Along with this, winds remain southerly which many times limits mixing potential. Offsetting this will be wind gusts of 35 to 45 mph and fairly dry fuels. Farther west into eastern South Dakota relative humidity drops to 20 to 30 percent with these strong winds and some better potential for deeper mixing, however with an incoming wind shift to the west and northwest direction, wind speeds drop off from mid to late afternoon which will aid in limiting the fire spread potential. So, long story short, no fire weather headlines on Thursday for now with the disconnect in strongest winds and lowest relative humidity.

Fire weather concerns continue for Friday, especially near and north of I-90. Afternoon relative humidity drops into the teens in most locations with wind gusts ranging from 15 to 20 mph near the Missouri River to 25 to 35 mph near and north of I-90. With deep westerly flow and a fairly strong pressure gradient, Friday could prove to be a day with a little enhanced mixing which usually means a bit warmer, a bit drier and a bit windier, on a day that already will see dry and windy conditions.

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 /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1216 AM CDT Wed May 13 2026

VFR conditions and mostly clear skies are expected to prevail for this period. Winds will be light and variable through the overnight and most of Wednesday. By the afternoon winds become southerly but remain light through the end of the period.

FSD WATCHES/WARNINGS/ADVISORIES

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