textproduct: Aberdeen

KEY MESSAGES

- A Slight Risk (Level 2 of 5) for severe weather is in place for storms this afternoon and evening, mainly east of the Missouri River. Large hail of 1-2" in diameter and wind gusts of 60 to 70 mph are the main threats. Tornadoes will be a secondary threat, as will flash flooding due to heavy rainfall. Areas west of the Missouri River are under a Marginal Risk (Level 1 of 5).

- Thursday, another Slight Risk for severe weather is in effect along and south of US Highway 12. Areas to the north of US Highway 12 are under a Marginal Risk. Large hail of 1-2" in diameter will be the main threat, with wind gusts of 60 mph as a secondary threat.

DISCUSSION

Issued at 235 AM CDT Wed Jun 3 2026

Sub-severe showers and storms are overhead early this morning, and the expectation is that storms will continue to weaken as they move east. Some weak showers to perhaps isolated thunderstorms will linger through the morning, but expecting very little out of what remains of these storms.

Focus then shifts to the severe threat this afternoon and evening. Model guidance has trended storm development a bit to the west, mainly along a cold front that will be passing through during the course of the day. Storm mode will begin as discrete cells (forming between the James River Valley and Missouri River) before turning into a line of storms in the evening as they progress east of the James River. Hail is expected to be the main threat, particularly with the earlier storms. Significant hail development (2"+ in diameter) will be possible, with 2000-2500 J/kg of CAPE, 30-40 knots of shear, and mid-level lapse rates > 7 C/km all supportive of the threat. Severe wind gusts will be the secondary threat, with northeastern South Dakota being the main potential threat area with the linear storm mode. DCAPE over 1000 J/kg will be present, along with near-surface lapse rates of 8 C/km, supporting easier mixing to the surface. Concern for tornadoes will also be in place, although there is a bit more uncertainty here. Low-level shear will likely be the main limitation here, but can't rule anything out at the moment. Also can't rule out heavy rain leading to flooding either, although this will be most prevalent while storms are in the discrete mode early on. Once storms form the line, the chances for training and/or slow moving storms are expected to decrease.

Another Slight Risk is in place Thursday evening, with the main threat being over central South Dakota. Strong CAPE > 2000 J/kg will be present in that area, along with shear of 40-50 knots. This along with lapse rates of 7 to even 8 C/km will support severe hail as once again being the main threat. Wind and tornado threat is less of a concern at the moment. However, can't quite rule out a stray gust or two with some marginal DCAPE over central South Dakota, nor can tornado development be entirely disregarded. At this point, the most favorable locations for both of those hazards will be over central South Dakota, as is the largest hail threat.

A weak upper-level ridge builds overhead late Friday into Saturday, temporarily cutting off precipitation chances for the weekend. This break may not last long however, as ensemble confidence remains fairly high on another upper-level trough developing over the western CONUS by next week.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1242 AM CDT Wed Jun 3 2026

Terminals KABR,KATY,KPIR,KMBG

Convection timing and intensity will be the primary concerns for the forecast period. Ongoing convection over south central SD will shift to the east through the night. Thinking that the thunder threat will diminish with time, so showed PROB30s for the showers potentially making it far enough east/northeast to reach KABR/KATY. Meanwhile, expect KPIR to stay primarily rain showers as the existing thunder threat departs to the east and the upstream convection likely stays south of the site.

Convection is expected again this afternoon as a cold front moves east through the area. Expect initial development in central and especially north central SD around 20-21Z, then spreads to the east-southeast with time through the evening. Tried to time out the best rain/thunderstorm threat in the FM/PROB30 groups, with future TAF issuances likely being able to bump the thunder into the FM groups. Finally, behind the front, could see some MVFR ceilings in north central SD (KMBG) in the evening.

ABR WATCHES/WARNINGS/ADVISORIES

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