Space Weather Predictions while a Solar Cycle Fades (Invited Presentation)

Solar Cycle 24 has almost disappeared and we anticipate Solar Cycle 25 will begin its rapid rise in a year or two. We have learned much about predicting solar activity in Solar Cycle 24, especially with the data provided by SDO and STEREO. These advances have come in the short-term predictions of solar flares and coronal mass ejections, which have benefited from applying machine learning techniques to the new data. The arrival times of coronal mass ejections is a mid-range prediction whose accuracy has been improving, mostly due to a steady flow of data from SoHO, STEREO, and SDO. Long-term (greater than a year) predictions of solar activity have benefited from helioseismic studies of the plasma flows in the Sun. While these studies have complicated the dynamo models by introducing more complex internal flow patterns, the models should become more robust with the added information. But predictions made long before a sunspot cycle begins still rely on precursors. I will describe the prediction of the SODA polar field precursor method, which has accurately predicted the last three cycles, for Solar Cycle 25. I will also examine the so-far unpredictable aspects of solar activity, coronal holes and their high-speed streams, with an eye towards understanding the polar regions of the Sun.