textproduct: Sioux Falls

KEY MESSAGES

- Showers and very isolated thunderstorms expected tonight into Saturday (80-90 percent chance near and north of I-90).

- 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).

- A very small chance the severe weather could creep north towards northwest IA and the Mo River Valley Sunday night, but confidence is very low.

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

UPDATE

Issued at 853 PM CDT Fri Apr 24 2026

The forecast remains largely on track for tonight and tomorrow. Currently we have some areas of rain stretching from central South Dakota near and west of the James River and into north- central Nebraska. This activity will spread east-northeastward through tonight. Did bump up the winds slightly for tonight, blending in some CONSShort and a bit of NBM 90th as the rain/virga has been able to mix slightly higher gusts down as the precipitation initially fights through a dry sub-cloud layer. The highest wind gusts will generally be around 25 mph, so nothing too strong especially compared to winds we've seen recently.

Temperatures tonight look to drop into the middle 30s to lower 40s, coldest over south-central South Dakota. If temperatures trend a degree or two cooler in that area, the freezing level may be low enough to allow for a few snowflakes to mix in with the rain. This would not cause any impacts though because of warmer ground temperatures, so no concerns if it happens to occur.

Heading into the day Saturday, rain looks to continue as warm air advection increases a bit. A few thunderstorms remain possible in the afternoon mainly near and east of I-29 and into northwest Iowa where there will be warmer temperatures and more destabilization. Still looking like any storms will remain sub-severe. Highs on Saturday look to range from the middle 40s in south-central South Dakota to the middle 60s over northwest Iowa.

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 /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 650 PM CDT Fri Apr 24 2026

An area of rain over western South Dakota is beginning to move into our area to start the period. This activity will bring MVFR to locally IFR ceilings for areas mainly near and west of the James River tonight before spreading eastward to the I-29 corridor through the daytime morning hours Saturday.

Activity looks to be a bit more scattered in nature down by KSUX during the day Saturday, so only added PROB30 groups there for now. However, guidance is also indicating that a couple of thunderstorms may develop by the Highway 20 corridor Saturday afternoon, but confidence was not high enough in location and coverage of -TSRA to warrant mentioning in the TAF at this time.

Winds look to be light and variable for the most part tonight into tomorrow morning, with a slight uptick in east- northeasterly winds Saturday afternoon.

FSD WATCHES/WARNINGS/ADVISORIES

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