textproduct: Aberdeen

KEY MESSAGES

- There is a Marginal Risk, level 1 out of 5, for severe storms for portions of central South Dakota this evening and tonight and a Marginal Risk again Monday evening through Monday night along and east of a line from Philip to Sisseton. Main threats include 1 inch diameter hail and wind gusts of 60 mph. Brief heavy rainfall is also possible.

DISCUSSION

Issued at 138 AM CDT Sun Aug 16 2026

Zonal flow continues this morning turning northwesterly aloft this evening as a negative tilted ridge amplifies a bit over the western CONUS with an ongoing large troughing pattern in Canada. Quiet conditions expected through this afternoon as high pressure centers itself over the region. The high pressure system will exit towards the southeast tonight into Monday morning as a surface trough, extending from a deepening low tracking across Canada, will track east/southeast across the region Monday followed by a cold front plunging southward out of Canada Tuesday.

CAMS keep the storm potential spotty as a cluster of storms are forecast to move into north central and another area into central/south central SD, tracking southeast this evening through tonight. There is timing and coverage differences between the individual CAMs with NBM doing a good job broadbrushing pops between 35-45% mainly along and west of the Mo River. CAPE generally will be at and below 1000j/kg but shear will be around 30kts. A lack of a LLJ will keep the threat low for any organized severe storms or long lasting storms. With more of an isolated threat, the SPC has a Marginal Risk, level 1/5, for severe storms over portions of central SD this evening into tonight.

As the trough tracks eastward across the Dakotas Monday, CAMs indicate additional spotty chances of showers and thunderstorms continuing here and there, mainly east of the Mo River during the day (where the trough will be) and along and east of the James River in the afternoon and evening as the axis of the trough moves over this area. Better development (and more of a threat for organized severe storms) seems to occur to our east/southeast of the CWA, per HREF. Winds at 500mb will increase between 40-50kts Monday evening with CAPE values increasing to around 1500j/kg over south central to northeastern SD/MN, bulk shear of around 30-40kts, with dps in the 60s. However, there is not much in a way of a LLJ as speeds are forecast below 20kts nor steep lapse rates. So this keeps down the threat for long lived severe storms through the overnight hours. Due to this, the SPC has highlighted a Marginal Risk again (level 1/5) due to this isolated threat mainly along and east of a line from Philip to Sisseton. Hail 1" in diameter and 60 mph wind gusts are possible along with brief heavy downpours.

The cold front from this system will plunge southward Monday evening into Tuesday bringing additional shower and thunderstorms chances. Behind the system, shortwave energy continues and if it can line up with the surface boundaries over the region, additional threat for rain and storms continues through the end of the week.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1222 AM CDT Sun Aug 16 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are expected at all terminals through this forecast cycle.

ABR WATCHES/WARNINGS/ADVISORIES

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