textproduct: Aberdeen

KEY MESSAGES

- Areas of fog are expected this morning over northern SD into west central MN with reductions in visibility potentially down to below 1 mile.

- There is a Marginal risk (level 1 out of 5) for severe storms over central and northeastern SD and west central MN Saturday evening into the overnight hours. 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 Saturday. Highs in the upper 80s to upper 90s are expected.

UPDATE

Issued at 820 AM CDT Fri Sep 4 2026

For the most part, the forecast is on track. Did end up issuing a Dense Fog Advisory for portions of central and northeast SD into west central MN for the next couple hours.

UPDATE Issued at 627 AM CDT Fri Sep 4 2026

Aviation discussion updated below for the 12Z TAFs.

DISCUSSION

Issued at 139 AM CDT Fri Sep 4 2026

Central and northeastern SD and west central MN will be getting a little bit of a break from the scattered early morning showers and storms today. While there will not be any showers, weaker winds over northeastern SD and west central MN as well as high relative humidity values will help patchy to areas of fog to develop this morning. This fog could cause localized areas of visibilities to drop below 2 miles at times this morning over portions of northeastern SD and west central MN, which should dissipate once the sun rises. As this is happen, an upper level ridge will start to build over SD into the weekend. The flow under this ridge will help warm, moist air to move into central and northeastern SD today and into the weekend. Temperatures today will be about 10-15 degrees warmer than normal, with highs in the upper 80s to mid 90s. Things will warm even more Saturday, with highs in the upper 80s to upper 90s. With the warm, humid air around Saturday, the heat index values could reach the triple digits in some areas over central SD.

Models are forecasting multiple upper-level shortwaves to move along the top of the ridge over SD. There is slightly lower confidence in the timing of these shortwaves as the models are not in consensus on it. While these shortwaves could provide upper-level support for shower and storm development, there also needs to be a source of lift at the surface. There will be a lee of the Rockies surface trough sitting over western SD and models are hinting at an attached warm front slowly moving in and sitting over the area this afternoon and into the weekend. These boundaries will be able to provide some of the lift needed for shower and storm development, though the storms will need to overcome a fairly decent cap to have any longevity and/or become severe. This cap is from an inversion due to the warm air moving in aloft. Instability will be building over central and northeastern SD today, with CAPE values of 1000-2000 J/kg over the area this evening. With this instability, as well as the moisture moving in and the lift from the surface trough and warm front, showers and storms could try to develop late this afternoon into tonight. However, there is lower confidence in this as they would have to be able to overcome the cap. As stuff tries to develop, it could cause some isolated pulse, pop up showers and storms that could try to get going but are not able to stay up for very long. If anything were able to overcome the cap and become a stronger storm, there will be lapse rates of 7-8 C/km and bulk shear values of 35-40 kts that could help the storm to have some larger hail develop, though there is very low confidence that this will happen.

Depending on when the upper-level shortwave move through, these pulsy showers and storms could pop up and move over central and northeastern SD tonight through Sunday. The model soundings show that there is plenty of instability and moisture that sticks around though Sunday to help things develop. The instability will increase Saturday afternoon and through the night to be between 1000-3000 J/kg over SD. With steep mid-level lapse rates between 6-8 C/km and bulk shear values of 30-35 kts over central and northeastern SD, the environment will be primed for severe storms to develop with large hail and gusty winds Saturday afternoon and into the overnight hours. There is a Marginal risk (level 1 of 5) for these storms to become severe. While these storms will most likely develop along the surface trough in western SD and then move into central SD, there is lower confidence in the timing and how far east they will make it do to models all varying the outcomes because of how they handle the upper-level support from the shortwaves. This will need to have an eye kept on it to see if models start to come to more of a consensus.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 627 AM CDT Fri Sep 4 2026

Terminals KABR,KATY,KPIR,KMBG

Patches/areas of FG/BR (IFR/MVFR VSBY) across northern SD this morning, along with patches of IFR CIGs. KABR/KMBG/KATY stand a chance to see these conditions this morning and have inserted TEMPO mentions for this. Otherwise, VFR conditions are forecast once the fog and low clouds burn off later this morning. There is a small area of SHRA/TSRA across southwest SD and northwest NE moving off to the northeast. Will be watching this for potential movement into central SD later this morning into early afternoon. No mention of this in KPIR/KMBG TAF for the time being, but will continue to monitor.

ABR WATCHES/WARNINGS/ADVISORIES

SD...Dense Fog Advisory until 11 AM CDT this morning for SDZ006- 008>010-016-017-021-037. MN...Dense Fog Advisory until 11 AM CDT this morning for MNZ039-046.