textproduct: Aberdeen

KEY MESSAGES

- There is a Marginal risk (level 1 out of 5) for severe storms over central and northeastern SD and west central MN this afternoon into tonight, as well as on Sunday and Monday. The primary hazards will be 1 inch in diameter hail and 60 mph wind gusts.

- Our warming trend continues into the weekend, peaking at 15 to 20 degrees above normal today. Highs in the low 80s over northeastern SD to upper 90s over central SD are expected. Higher humidity values over central SD will lead to heat index values in some places to get into the triple digits.

UPDATE

Issued at 805 AM CDT Sat Sep 5 2026

No changes planned to the today period forecast. The forecast contains some locations running heat index values up to ~97-102F degrees this afternoon across central/north central South Dakota for maybe 3 or 4 hours. Satellite and surface obs hint at a cool/stable boundary layer over the CWA in the wake of last night's/early this morning's convection. So, unless there were to be some new (elevated) mid-level WAA-forced showers/storms out across the northeast corner of CWA, there shouldn't be any further areas of precipitation over the CWA today. Will likely have to wait for daytime heating to destabilize the BL and for the shortwave energy noted back over Wyoming and Utah to make its way over into this region many hours from now. By late this afternoon, models depict plenty of instability (RAP13 has ~2000-3500J/kg CAPE) and deep layer shear (RAP13 has ~20-35 knots) will be around for multi-cellular to super-cellular storm modes, continuing into tonight. Best low level jet tonight is currently progged to set up across northeast South Dakota, eastern North Dakota and the northern half of Minnesota. This is probably also where the best low/mid-level WAA and moisture advection juxtaposes with the strongest deep layer shear around.

UPDATE Issued at 628 AM CDT Sat Sep 5 2026

Aviation discussion updated below for the 12Z TAFs.

DISCUSSION

Issued at 140 AM CDT Sat Sep 5 2026

As an upper-level shortwave has moved over SD last night into this morning, scattered showers and storms continue to pop up and move over areas east of the Missouri River. The low level jet has set up over the area and has been helping to develop and support these showers and storms and it will continue to support them into the morning. Confidence in the timing of showers and storms is a bit low this morning, as the high-res models have had a harder time correctly showing what is actually happening when they initialize, which makes a person have a harder time trusting what the models have happening later on in the run. With warm, moist air continuing to move into central and northeastern SD, the environment is primed for showers and storms to continue to develop early this morning. CAPE values this morning are between 1000-2000 J/kg over central and northeastern SD. There are mid-level lapse rates of 7-8 C/km and about 30-40 kts of shear in the environment. While so far the scattered pulsy showers and storms haven't become severe, if they are able to get strong enough to tap into the environment and the support of the low level jet, then they could become severe. If that happens, then the storms could have hail up around 1 inch in diameter and wind gusts of 60 mph. After the low level jet dies back this morning, the showers and storms will likely back off for a few hours.

More warm, moist air will be pushing into central and northeastern SD today. Temperatures will be getting up into the low 80s over far northeastern SD and increase to the west with highs in the upper 90s. The higher humidity values will cause the heat index values over central SD to increase and get into the triple digits in some areas. After the showers and storms move through this morning, the heat and humidity will help to increase CAPE values back up to 1000- 3000 J/kg this afternoon and tonight. 850mb temperatures will also be warmer today, with models showing temperatures between 20-28 degrees C. These temperatures will help to place a pretty decent cap over central and northeastern SD. This will likely be a similar situation to yesterday, where there will be scattered junky and pulsy showers and storms that start to pop up in the afternoon along the surface trough in the Rockies and the attached frontal boundary that stretches from northwestern to southeastern SD and showers and storms will continue this pattern through the night. However, with the potential for an upper-level shortwave to provide support to the storms at some point as well as an environment conducive to severe storms if they can break through the cap, some storms could become severe. Lapse rates late this afternoon into tonight will be between 7-8 C/km and bulk shear will be between 35-45 kts. With this environment in place, there is a Marginal risk (level 1 of 5) for storms to become severe, with hail up around 1 inch and wind gusts of 60 mph possible. Confidence in timing for these storms is low due to the cap that will be in place and not knowing where and when something might be able to break through a weak point.

While moisture will continue to move in over central and northeastern SD Sunday and Monday, the surface temperatures will cool slightly. High temperatures these days will be in the low 80s to low 90s. Instability will start to increase again over central SD Sunday, with CAPE values in the afternoon into the nighttime hours between 1000-2000 J/kg. As more upper-level shortwaves move over SD, they will be able to provide support for showers and storms to continue to develop along the surface trough and frontal boundary that have parked themselves over the state. Slightly cooler temperatures aloft will help to weaken the cap slightly, however with 850 temperatures still looking to be between 18-24 degrees C, there will still be a cap to limit storm development. As with yesterday and today, there could be junky, pulsy scattered showers and storms through the afternoon and night in this environment. Lapse rates look to be slightly weaker Sunday, between 6-7 C/km, as well as a bit weaker shear over the area compared to today. If a storm is able to break through the cap, there is a marginal chance (level 1 of 5) it could become severe Sunday afternoon through the overnight. The primary hazards will be hail up to 1 inch and wind gusts of 60 mph. While the start of Monday looks to have similar conditions, an upper-level trough will be pushing the ridge that sits over the area out, while also providing support for a cold front to push through overnight Monday into Tuesday. This will have more storms along it, but once the front pushes out of central and northeastern SD, we will finally get a little break from the pattern we have been stuck in as well as some cooler temperatures.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 628 AM CDT Sat Sep 5 2026

Terminals KABR,KATY,KPIR,KMBG

Areas of -SHRA/SHRA and -TSRA/TSRA still lingering near the KABR/KATY terminals at 12Z this morning, although expecting this activity to dissipate/depart the region by mid/late morning. There are also some patches of MVFR CIGs across northeast SD which could briefly affect KABR/KATY this morning. For this afternoon, generally VFR conditions are forecast. There is a threat for additional TSRA activity late this afternoon into the nighttime hours, but confidence on areal coverage and locations of these storms is low. Will defer to later TAF issuances for possible insertion of PROB30.

ABR WATCHES/WARNINGS/ADVISORIES

SD...None. MN...None.