Eastern South Dakota
A few cities include: Aberdeen, Sioux Falls and Watertown.
Local tornado season: Peaks in June, but May and July are active in some years.
Terrain: Mostly plains with some ponds, lakes and rivers.
Road network: Relatively good in most areas.
Radar coverage: Good, except in south-central South Dakota.
Eastern South Dakota experiences more tornadoes in most seasons than western parts of the state. There have even been a few strong, long-track tornadoes, so significant tornado events are not totally unheard-of here. Large to occasionally very large hail are potential hazards as well. Some developing squall lines will also produce damaging winds in eastern South Dakota.
Terrain
Eastern South Dakota, for the most part, has very friendly terrain for storm chasing. The Missouri River forms a valley across the middle part of the state, another valley/lowland is evident in eastern parts of the state. Overall, the land feels like classic plains territory, other than the fact that it is a bit “wetter” with several ponds and small lakes dotting the countryside. Some gentle, rolling hills separate the two valleys. Away from rivers there are not too many trees across most of eastern South Dakota.
Road network
As favorable as the terrain is, the road network is mostly cooperative for storm chasing, too. Most primary roads either run north-south or east-west across eastern South Dakota and secondary roads continue the grid-pattern in between. There are some gaps from time to time, but these are generally not too obtrusive when it comes to storm chasing. Interstate-29 runs north-south in far eastern South Dakota, while I-90 is the freeway that travels west from Sioux Falls and east into southern Minnesota.
Radar coverage
Eastern South Dakota has two radar sites in KABR and KFSD. Radar coverage starts to become limited to the west and there is little to no coverage available as one gets close to the Missouri River. This lack of radar can be particularly rough. Storms will often move from west to east across South Dakota, crossing through large radar hole. Without radar being able to sample the storms in the area, you will need to rely on your own visual cues from the sky and perhaps some help from observations/mesoanalysis and satellite imagery.
In summary, eastern South Dakota is generally favorable when it comes to storm chasing. The terrain is relatively flat, the road network, for the most part, is good and terrain issues are minimal. Radar data does start to drop out toward the Missouri River, but will good visibility to the west; perhaps you can let your eyes do the storm analysis.
Notes
Far southeastern South Dakota, near the Missouri River, has not been included in this chase zone, as it is grouped within the Mid-Missouri Valley area.