Another mild day is in the forecast, but big changes are ahead as a powerful storm system heads toward the region the next few days. Starting with today, high temperatures will be near 80 in Sioux Falls with a breezy southeast wind at 15 to 25 miles per hour. Also, areas of showers and thunderstorms will be developing during the afternoon, becoming more numerous during the evening. A couple of the storms could become severe, but most will produce locally heavy downpours and lightning. Farther north, Aberdeen and Pierre will both be mild in the lower to middle 70s today with a slight chance of rain extending as far north as Aberdeen. Rapid City looks partly cloudy, with a stronger north wind at 20 to 40 and highs in the mid 60s.
Tonight's forecast calls for areas of showers and thunderstorms to move east into southern Minnesota and northern Iowa, with other areas of showers developing in far western South Dakota into the northern Black Hills. Areas of rain will be most likely in western KELOLAND on Thursday AM, with temperatures holding in the mid 50s in Rapid City. Sioux Falls will be near 70, with Aberdeen and Pierre in between in the 60s.
More widespread rainfall will develop across KELOLAND Thursday night into Friday. Rain will likely change to snow in the Black Hills Thursday night into Friday, leading to a winter storm watch in effect for that area. This means the potential for 6 inches of snow is possible.
Colder north winds will continue to filter through KELOLAND on Friday, except for the southeast where thunderstorms could develop in northwestern Iowa Friday afternoon. In fact, the Storm Prediction Center has posted a severe weather outlook for our northwest Iowa counties at that time.
As colder winds filter in Friday night into Saturday, more rain will mix with snow in parts of central and western KELOLAND. It's still too early to speculate how much snow will fall. However, we will continue to watch the latest trends as the system develops throughout the plains on Saturday. It looks like at the very least, very chilly rain will occur on Saturday with cold north winds at 20 to 40 miles per hour. A frost or a freeze is possible on Sunday morning, followed by highs in the upper 40s low 50s on Sunday. Slightly warmer trends should return to most of the area by Monday and Tuesday.
One more story…heavy rain totals are possible over the next few days at 1-2” in many areas. Stay tuned.