My last indicator for winter, a cold surge from east, won't occur any more (or is very unlikely to occur). For this reason winter 2015/16 will never reach 100% - which corresponds with the general impression we have of this "winter". There are already several signs for early spring but they aren't in my list for the four main seasons; therefore spring 2016 is still 0% (doesn't match our feeling). There are two ways to incorporate such observations: allow indicators for early and late spring as well and thus have more indicators for each of the four seasons [if I would deduct the indicators after the peak of the season I would get a sine-shaped diagram that would correspond the sun's declination] or define up to 12 seasons (early, mid/high and late).
