Interesting day with a 6,300′ QNH average cloud base later on in the afternoon. The only fly in the ointment was some weak wave interference which gave large areas of sink and made a lot of clouds look as though they should work but didn’t when you flew under them. It was a day to get high and stay high. The cloud base was very variable and I climbed to 7,250′ QHN in one patch with an exceptionally high base but got spat out before I managed to contact any wave. Depending on where you were in relation to the wave the thermal strength varied from a just sustainable 1-2 kts up to one very useful 7.5 knotter. Even the main ridge started to work with the help of the occasional thermals later on in the day.