textproduct: Sioux Falls

KEY MESSAGES

- Additional shower and very isolated thunderstorm chances are possible Monday afternoon into Monday night. If a storm can develop, wind gusts to around 50 mph will be possible. The better chances will be south of Highway 18.

- After seasonal temperatures into Monday, cooler than normal temperatures return midweek. Areas of early morning frost or near- freezing temperatures are possible by early Wednesday and Thursday.

UPDATE

Issued at 855 PM CDT Sun May 3 2026

The forecast tonight remains on track. Southwesterly winds look to increase near and after midnight mainly along the Highway 14 corridor of eastern and central South Dakota into the higher elevations of the Buffalo Ridge as a low pressure system deepens over western Ontario. Gusts in these locations tonight will push towards 25 mph, locally to around 30 mph in the Buffalo Ridge. This system will also bring a cold front through our area during the daytime morning hours Monday, turning winds northwesterly. Strong cold air advection behind the front will lead to another increase in winds on Monday, this time across the entire area. Winds will generally gust to 30 to 35 mph by Monday afternoon, strongest west of I-29.

Guidance continues to show some showers moving through the area behind the front as some mid-level vorticity rounds the base of the trough. A dry sub-cloud layer will keep most of this activity as sprinkles, but there does appear to be enough lift in the DGZ to allow for some light showers from time to time. And with some instability in parts of northwest Iowa, a rumble of thunder is also possible. With the dry air, sprinkles/showers could mix down a 40 mph gust, while a thundershower, if one develops, could bring down a very isolated 50 mph gust to the surface.

DISCUSSION

Issued at 152 PM CDT Sun May 3 2026

Northwest winds will gradually diminish through the afternoon and turn more westerly this evening. Some very localized elevated fire weather conditions are expected where some of the warm season grasses remain fairly cured.

A broad trough to the north will settle south tonight into Monday. This will initially turn winds to the west and southwest tonight, before turning north on Monday morning. For the most part this will be a dry front, but some mid level moisture and very weak instability may allow for a light shower. Otherwise, in the afternoon in mainly northwest IA some weak instability could allow for an isolated shower or thunderstorm, with no severe weather expected. As with last nights showers some gusty winds will be possible with any showers.

The main changes with this incoming front will be cooler, below normal temperatures. Highs on Tuesday and Wednesday will be in the 50s, with morning lows Tuesday, Wednesday and Thursday mostly in the 30s. Areas north of I-90 could see some frost and freezing temperatures all 3 mornings while areas near and south of I-90 will see the better chances for frost and freezing temperatures on Wednesday and Thursday mornings.

Otherwise, northwest flow aloft will be in place Wednesday into the next weekend which suggests that even if we can get a few waves to move through the area, moisture and instability will be a bit lacking. Temperatures Thursday into the weekend do climb back to around or a bit above normal with highs mostly in the mid 60s to lower 70s. Very little consistency in the model output for these weak waves so confidence on any isolated to scattered showers is pretty low.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 102 AM CDT Mon May 4 2026

VFR conditions expected through the period. LLWS concerns are expected mainly north of I-90 through just before sunrise as the nocturnal low level jet continues to strengthen. A cold front will move through the area through the daytime hours Monday morning, turning southwesterly winds to northwesterly. Winds behind the front will also increase, with gusts to 30 to locally 35 kts this afternoon, strongest west of I-29. Isolated to scattered sprinkles/light showers are possible mainly this afternoon and evening, and some of these showers could bring down some higher gusts as well. Instability continues to trend downward, so thunder is unlikely. Winds will begin to diminish this evening across the area.

FSD WATCHES/WARNINGS/ADVISORIES

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