Winds are cranking up in Sioux Falls and SE KELOLAND, a brisk south wind that is drawing moist air into KELOLAND. A cold front, with a wind switch to the north, is already working its way through northern South Dakota. Ahead of the front it is very warm, with temperature rising through the 80s. It is ten to fifteen degrees cooler behind the front in northwestern South Dakota.
This evening and overnight, that incoming front may produce strong or severe thunderstorms in Sioux Falls and SE KELOLAND. The Storm Prediction Center has rated the area a slight risk of severe weather. The expectation is for isolated or scattered thunderstorms, producing damaging winds and hail. There could also be some pockets of heavy rainfall during the evening and nighttime hours.
Otherwise, just a few light showers in northern and western South Dakota, with the north wind cooling areas behind the front to the mid 40s to low 50s with partly cloudy skies.
After the thunderstorms end tomorrow morning, skies will clear and it will be a sunny but cool day. Highs will be below-normal, in the upper 60s to low 70s Friday afternoon.
The weekend still looks great. Sunny and warm – but also breezy both days. Saturday’s highs will be in the upper 70s to low 80s East River, and the upper 80s to low 90s West River.
Sunday will also be sunny and breezy, with the upper 80s to low 90s – more than ten degrees warmer than normal for the final weekend of summer.
Models have come into agreement for a widespread round of thunderstorms on Monday. How strong they will be is yet to be determined. It will also be a breezy day with the thunderstorms, and highs will be in the mid 80s for western and central South Dakota. Rapid City will be much cooler – around 70 – behind the main cold front.
The middle part of the week looks cooler, below normal, in the mid 60s to low 70s. that includes Wednesday, the first day of Autumn. Temperatures may recover a little for the end of the week and the following weekend (September 25-26).