textproduct: Sioux Falls

KEY MESSAGES

- Showers and very isolated thunderstorms expected through this evening with the greatest chances across southeastern South Dakota into far western Minnesota (80%+). Chances taper off through late evening and tonight, but scattered (30-40% chance) showers remain.

- Scattered to numerous (80-100%) showers and storms expected again Sunday into Monday. Areas of heavier rainfall are possible but for now flooding and flash flooding chances remain low (less than 20 percent).

- Isolated severe risk for areas south of a line from Lake Andes to Sioux Falls to Cherokee Sunday night; confidence remains low in occurrence (less than 20%). If a stronger storm develops, damaging wind gusts and hail are the primary threats.

- Seasonable temperatures expected through next week, with highs mostly in the mid 50s to mid 60s.

UPDATE

Issued at 259 AM CDT Sat Apr 25 2026

Rain continues to move to the northeast early this morning as a mid level wave slides across northern SD. Rain is reaching the ground now from Chamberlain to Marshall, with areas further to the south and east still struggling with saturation. Have refined the short term pops to better reflect areal coverage following some of the CONSShort guidance. Expect more locations to saturate through the overnight, so should see showers expand by daybreak as additional precipitation moves north out of central NE. Lightning has tapered down over the last hour or so, but can't entirely rule out a rumble or two of thunder. Temperatures are in the upper 30s to mid 50s, and expect morning lows in the upper 30s to mid 40s. Soundings still hint at possibly an hour or so of snow mixing in with the colder temperatures in south central SD, but not expecting any impacts or accumulations if this occurs.

Forecast through today and tonight remains on track, with WAA and a subtle mid level wave keeping showers around the area, with isolated thunderstorms. Severe weather is not expected with scant instability. Highs remain on track to be in the mid/upper 40s for south central SD in to the mid 60s in northwestern IA. Somewhat breezy conditions along with rain and clouds will make it feel a bit cooler.

DISCUSSION

Issued at 1243 PM CDT Fri Apr 24 2026

Upper level low pressure well to the north of the area will swing a smaller piece of energy into the area tonight into Saturday. Fairly strong mid level frontal forcing develops in response to this wave, with some of the stronger forcing in the 700-750mb layer. Late tonight into Saturday morning the front closer to 800-850 mb looks to be more active and could shift some of the better precipitation closer to I-90. Overall amounts within this band of rainfall will likely be about a quarter to three quarters of an inch. Instability is minimal so other than a few rogue lightning strikes this will mainly be a welcome rain event.

Weak upper level support and low to mid level warm advection continues through most of Saturday and given some very weak instability in the soundings, scattered showers will remain likely through the day. Some isolated thunderstorms will also be possible, but severe weather is not expected tonight through Saturday. The better chances for rain should remain mostly north of I-90 but could be a little more spread out across the area with isolated to scattered activity and more disorganized forcing.

Weak upper level ridging builds ahead of a stronger wave Saturday night into Sunday morning. This could be a period where activity is the most isolated.

Upper level support rapidly increases Sunday afternoon into Sunday night, leading to the areas best chance for some heavier rain Sunday night into Monday. Marginally steep elevated lapse rates along with strong low level moisture convergence will lead to showers and thunderstorms for much of the area. The trends to watch for on Sunday night will be the potential for the better forcing to produce heavier rainfall west of I-29 towards central into northeast SD and another area closer to northwest IA and points south where deeper instability could produce an MCS with that activity shifting more eastward. A very small threat for severe weather in northeast NE and northwest IA Sunday night, although model soundings and Ensemble output indicate only a very small chance for CAPE values above 1000 J/kg.

Low pressure aloft deepens over southeast SD Sunday night and slowly drifts east through Monday. This will continue the threat for rain into Monday afternoon, likely ending Monday evening most locations.

Rainfall amounts continue to trend higher with the latest NAM producing a fairly large area of 2-4" of rain for most of southeast SD through tonight through Monday. The latest GFS is very similar, just a touch lower on amounts with the Canadian and RRFS a little farther north and west with the heavy rain amounts. The latest 50th percentile from the GEFS gives the area 1-2" with the higher amounts north of I-90. The Canadian ensemble parks the higher 2" amounts across most of southeast SD. The 6z EC Ensemble very similar to this output as well.

Once this system finally exits, mainly north to northwest flow aloft is expected Tuesday into Friday which will keep seasonally cool temperatures close to normal in place each day. While there will be a few chances for showers and maybe an isolated thunderstorm the activity looks to remain fairly isolated and fairly light.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1243 AM CDT Sat Apr 25 2026

Rain continues to spread into the area from southwest to northeast, bringing in MVFR to locally IFR ceilings. This will continue to spread through our area through Saturday morning, with activity becoming a bit more scattered in nature by the afternoon especially south of I-90. This may result in a couple of thunderstorms developing in the afternoon, but confidence still remains low enough to continue excluding -TSRA mention in the TAFs as any storms would likely be isolated. If storms can develop, northwest Iowa would be the main place to watch.

Winds will be mainly out of the east-northeast through the period, with the exception being over northwest Iowa where there will be east-southeasterly flow. Winds over northwest Iowa will turn to more northeasterly like the rest of the area by Saturday evening. Winds will remain fairly light through the period, though some showers may mix down a 20 kt or so gust at times.

FSD WATCHES/WARNINGS/ADVISORIES

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