textproduct: Sioux Falls

KEY MESSAGES

- Near critical to critical relative humidity leads to locally elevated fire danger today, despite lighter winds. Continue to use caution to prevent a spark.

- A return to more seasonable temperatures today through mid next week, with highs mostly in the mid 50s to mid 60s.

- Scattered (50-70%) showers and thunderstorms return tonight into Saturday. Scattered to numerous (50-90%) showers and storms expected again Sunday into Monday. Some locally heavier rainfall is possible.

UPDATE

Issued at 314 AM CDT Fri Apr 24 2026

Temperatures this morning are falling into the lower 30s and lower 40s as we've seen some breaks in the clouds and decreasing northwesterly winds. An area of high clouds is pushing east of the I- 29 corridor at the time of this discussion, with mid clouds moving through central SD. No significant changes to the forecast this morning, with cooler but seasonal temperatures today and clouds west of the James River. Locally elevated fire danger is expected today with near critical and critical RH values (around 25% or less) for most of the area; however, widespread concerns are tempered by light winds.

Still looks like dry sub cloud layer keeps much of the area dry into the early evening hours as the first short wave moves through earlier today. Anticipate shower and isolated storm chances to increase late tonight into Saturday morning from west to east as the next mid level wave and upper jet streak rotate around the upper low to our north and lower levels saturate.

DISCUSSION

Issued at 1256 PM CDT Thu Apr 23 2026

The severe weather threat for mainly northwest IA will gradually come to an end late this afternoon as the dry line/cold front race southeast. So far the front is a bit ahead of schedule so some potential for most of the activity to be out of our area by 4-5pm. The storms that do develop this afternoon will have about 1500-1750 J/kg CAPE and moderate shear so hail to the size of half dollars and wind gusts to 60 mph seem like the main threats. With the potential for some surface connection with the updrafts a very isolated tornado cannot be ruled out.

The fire weather threat will diminish this evening as temperatures fall and dew points increase behind the cold front. This will lead in to a quiet and cooler Friday with highs mainly in the upper 50s to mid 60s.

Rainfall probabilities for the weekend into Monday continue to indicate good chances for a meaningful rain. Not completely ready to jump on board just yet, but the data is starting to make it look difficult to miss out. Both the Canadian and EC Ensemble indicate a widespread 1" plus for pretty much the entire area while the GEFS suggests there will be a sharper cutoff from northwest to southeast with the higher amounts from northwest IA southward. Although the latest GEFS has increased rainfall amounts compared to yesterday across the entire area, just not as much as the Canadian and EC. Even a quick look at the 10th percentile suggests pretty much a quarter to a half an inch everywhere except closer to highway 14.

Right now the severe weather threat looks pretty low during this time. Will keep an eye on Sunday night into Monday as low pressure deepens and moves into the area. Maybe enough forcing to generate a few stronger updrafts. But all in all the instability tends to stay locked up from roughly I-80 southward.

The low pressure that brings the area the potentially meaningful rainfall will drift east towards the Great Lakes Tuesday into Thursday, leaving the area in drier northwest flow. This will continue the trend of near to a bit below normal temperatures. Precipitation chances will remain spotty through this time with a few weak waves expected to rotate southeast through the strong northwest flow.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 614 AM CDT Fri Apr 24 2026

Mostly VFR conditions through the period, with mid and a few high clouds, mainly focused west of I-29 early in the period. Showers move east from central SD through the day today and tonight; however, think that we'll remain dry during the day due to dry sub cloud layer, with bonafide showers moving in west of the James closer to 25.03z. Have refined the timing at KHON, and added a PROB30 of -SHRA at KFSD. Showers could lead to some MVFR conditions. Winds through the period remain light and somewhat variable in direction.

FSD WATCHES/WARNINGS/ADVISORIES

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