A Severe Thunderstorm Watch is already out for most of western South Dakota. That goes (for now) until 10:00 p.m. MDT but could be extended east and later into the night. There are also several individual supercells that are warned thunderstorms in far western South Dakota. We’ve had reports coming into the storm center of nickel-sized hail near Spearfish and Deadwood.
More storms are on the way this evening and overnight. The primary threats from these are large hail and damaging winds. There could also be isolated tornadoes this evening along the boundary we’re watching. These are more likely when the storms are separate, before they line up. Storms will push East River this evening. There are still good chances of rain, even heavy rain, East River. The best chance for rain in the east continues to be after dark. Today’s humid feel and warm temperatures are pushing along a wide boundary just north of I-90. Reinforcing energy from Colorado still isn’t quite here yet; once it gets here more storms will take off.
Along with hail, wind, lightning, etc. there will be heavy rain in many locations. Since the rains will likely continue through early in the workweek, localized flooding is a possibility. Moisture trackers now show that some could see more than FOUR inches of rain by the time it’s done.
Tomorrow the threat of severe storms pushes east into SE KELOLAND. More heavy rain is possible and a lot of this round will come late in the day. These storms still look to emerge from Nebraska and will be close to Sioux Falls late in the afternoon. Hail and winds are again the primary issues, with isolated tornadoes possible. Tomorrow will also be cooler for many of us, and there should be less lightning West River.
Monday and Tuesday will be cooler but the potential of heavy rain continues. Rain is likely up until midweek. By then, things start to quiet down and slowly warm. More showers are possible by Friday in Rapid City.