textproduct: Sioux Falls

KEY MESSAGES

- Light rain will continue into the evening though amounts are expected to be rather light. Occasional spits of rain/drizzle may persist overnight.

- Numerous showers with embedded thunderstorms will develop Sunday afternoon. Brief pockets of moderate rain will be possible into the early overnight, though storm motion will limit flooding potential.

- A stronger storm or two may develop Sunday evening and linger into the early overnight hours south of I-90. Hail would be the primary risk, but isolated wind gusts possible near Highway 20.

- After rain ends Monday afternoon an extended period of cooler than normal temperatures will continue through the week with only minor rain chances late Wednesday.

DISCUSSION

Issued at 1219 PM CDT Sat Apr 25 2026

THIS AFTERNOON: Mid-lvl vorticity tracking through central NE will continue to produce areas of light rain into the evening. Generally rainfall totals have been running well short of CAM guidance this morning, suggesting greater impact from linger dry air. As the wave slowly slides east, we'll continue to see forcing near both areas of 850 and 600mb frontogenesis. Absent any meaningful instability, rainfall rates will remain quite. One item of note: We have received a couple reports of sleet on the western side of the precipitation area this afternoon. This process should diminish as strong warm advection increases.

TONIGHT: After a light uptick in echos in NW Iowa early this evening, the initial wave of vorticity will move east after dark. In it's wake, a very weak low-lvl warm advection regime will stay in place. The persistence of this weak lift may allow sprinkles to isolated showers to linger into Sunday morning, but QPF amounts will again be very light.

SUNDAY-SUNDAY NIGHT: Broad and weak warm advection persists Sunday morning again allowing the development (or redevelopment) and northward propagation of sprinkles to very light showers through the Tri- State area. By the afternoon we'll begin to see a shift in the mid-lvl flow as troughing begins to eject out of the Central Rockies. The advection of weak to modest elevated instability along with both the increasing low-lvl convergence and nose of the upper lvl jet energy should allow for numerous showers and thunderstorms to form over Nebraska early in the afternoon. The increase and slight veering of the LLJ should push this activity northward into the Tri-state area in the evening. Rainfall rates based on HREF guidance may range anywhere from 0.10" to as much 0.75" per hour, but with the fast northeast progression of rain any flash flood risk should be minimal.

One hazard to monitor will be the progression and northward extent of mostly elevated instability lifting northward Sunday evening. Latest guidance would suggest the northward advection of mostly elevated MUCAPE of 400-800 J/KG south of I-90. Soundings suggest this is a tall but thin CAPE profile, and while overall shear/wind profile isn't all that strong, CAMS are suggesting potential for a few bowing segments with small hail mostly near the Highway 20 corridor.

MONDAY: Upper troughing ejects into the Plains early on Monday, keeping rain chances high throughout the daytime hours. Greatest focus for isolated thunder will be through the morning hours before mid-lvl dry air arrives. Further west, the deepening upper trough would suggest a deformation band develops west of the James River early and then drags itself eastward into the early evening. With temperatures stuck in the 40s, a rather raw and windy day may be expected.

TOTAL QPF POTENTIAL: This system remains one that should bring some relief to what's been a very dry Spring season. The latest HREF 25/75th percentile guidance suggests that by 7am Monday most should see between 0.75" and 2". By the time the deformation band tracks through, some model guidance suggesting localized 2.5-3" totals may not be far off. Of course, the track of convection Sunday evening will determine the final totals.

TUESDAY-FRIDAY: Confidence remains quite high that the rest of this week will be cooler than normal. Deepening low pressure over the eastern third of the CONUS will keep a persistent northwesterly low- lvl flow in the region. The resulting high temperatures will climb into the upper 50s to a few 60s, just a shade below normal. The only meaningful risk for additional rain this week will present itself on Wednesday night into Thursday as a subtle wave passes through the NW flow. At this time, with no instability, any amounts will be very low.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1219 PM CDT Sat Apr 25 2026

Light rain continues to move through the Tri-State are this afternoon. We're continue to see gradual lowering of ceilings towards MVFR levels, and potential for drops to IFR continue to possible in a narrow corridor into this evening. Visibility generally remains above 4SM.

Widespread light rain dissipates early this evening, only to be replaced by occasional very light isolated showers or drizzle. Ceilings may fall below 1000 ft AGL in a few pockets.

Rain showers try to redevelop Sunday morning, through greater coverage will be focused on the afternoon. MVFR ceilings expected to continue.

FSD WATCHES/WARNINGS/ADVISORIES

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