textproduct: Sioux Falls

KEY MESSAGES

- Isolated sprinkles to showers are possible this afternoon and may continue into the evening.

- Showers and embedded thunderstorms arrive by daybreak Tuesday and spread eastward in the day. Very isolated strong storm redevelopment is possible in the afternoon with a risk of hail. - Below normal temperatures continue through mid week before more seasonable temperatures return from late week into the weekend.

DISCUSSION

Issued at 1256 PM CDT Mon Jun 22 2026

THIS AFTERNOON/EVENING: Isolated to widely scattered sprinkles to showers will persist into early evening, as soundings indicate sharp low-lvl lapse rates and a small pocket of instability. The lack of low-lvl flow would suggest no strong organization to this activity. These sprinkles/showers may linger into the evening given weak perturbations in the mid-lvl flow, but QPF will be minimal.

TONIGHT: Ejecting shortwaves off the Central/Northern Rockies will develop several clusters of convection over the western Dakotas and Nebraska Panhandle this evening. With this activity outrunning most of it's meager instability by midnight, it will begin to cross into the western CWA by daybreak. While a low chance, a few 30 to 40 mph gusts may be possible.

TUESDAY: Showers and embedded thunderstorms move east through the CWA on Tuesday. Eventually by mid-day to the early evening a few pockets of clearing may try to develop along and ahead of a weak cold front drifting eastward. While soundings suggest instability is marginal (700-1000 J/KG), if those larger pockets develop (where the uncertainty in the forecast remains), slightly more unstable airmass could develop. Shear throughout the effective layer supports some storm organization, however mid-lvl lapse rates are marginal. All that said, a continued potential for isolated strong storms with hail will be possible Tuesday afternoon and early evening.

Wednesday: High pressure arriving will lead to a very pleasant and dry Wednesday. Temperatures rise into the middle to upper 70s.

THURSDAY-FRIDAY: Slightly cooler than normal temperatures remain in place for the end of the week as the mid-lvl flow remains westerly. A subtle trough passing through the Central Plains may cast an increase in cloud cover and perhaps a few showers through the MO River valley Thursday . A stronger upper wave ejects to the northeast by Friday bringing with it an increased chance for showers and thunderstorms (60+%) by Friday. Greatest potential appears to be north of I-90, but quiet a bit of variability remains with the track of this wave.

SATURDAY-SUNDAY: The longwave pattern appears to shift for the upcoming weekend, with this pattern amplifying into next week. By Saturday a long wave trough forms over the western third of the CONUS, with an increasing ridge in the southeastern part of the CONUS. Sharpening southwest flow over the Plains will help push both warmer temperatures and increasing convection risks through central Canada and the Northern Plains. Temperatures will also rise back to normal or above normal levels towards the 90 degree mark.

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.