  The Sun exhibits a well-observed modulation in the number of spots on its
disk over a period of about 11 years. From the dawn of modern observational
astronomy sunspots have presented a challenge to understanding -- their
quasi-periodic variation in number, first noted 175 years ago, stimulates
community-wide interest to this day. A large number of techniques are able to
explain the temporal landmarks, (geometric) shape, and amplitude of sunspot
"cycles," however forecasting these features accurately in advance remains
elusive. Recent observationally-motivated studies have illustrated a
relationship between the Sun's 22-year (Hale) magnetic cycle and the production
of the sunspot cycle landmarks and patterns, but not the amplitude of the
sunspot cycle. Using (discrete) Hilbert transforms on more than 270 years of
(monthly) sunspot numbers we robustly identify the so-called "termination"
events that mark the end of the previous 11-yr sunspot cycle, the
enhancement/acceleration of the present cycle, and the end of 22-yr magnetic
activity cycles. Using these we extract a relationship between the temporal
spacing of terminators and the magnitude of sunspot cycles. Given this
relationship and our prediction of a terminator event in 2020, we deduce that
Sunspot Cycle 25 could have a magnitude that rivals the top few since records
began. This outcome would be in stark contrast to the community consensus
estimate of sunspot cycle 25 magnitude.
