Yes, okay, we have a confession to make. We haven't done this section Northbound. Why? Take a guess. The net altitude gain is 4,636 feet. That's net. That's not counting the descent to Sunrise High Sierra Camp, the descent to Cathedral Pass and the descent to Tioga Road. The truth is, we like to end up in Yosemite Valley. If we're going to hike the distance, let's finish some place where we can stagger to a soft bed and pop open a bottle of sparkling wine. So when we did the trek from North to South (2002), we started at Tuolumne Meadows, stumbled out at Whitney Portal and then charged directly back in at Tuolumne for the descent. Suffice it to say that for people who don't cheat a little, the Southbound John Muir Trail adventure begins with a bit of an ascent. But if one were to decide on a direction based on the first few days of the trip, this end, though daunting for sure, might still be the preferred entry point. The net altitude gain is less severe than from Whitney Portal, and the highest altitude gained is but a fraction of Whitney's 14,500+ feet--a better warmup for JMT travelers.
The most amusing thing about doing this segment "northbound" is that shortly above Upper Cathedral Lake the trail crests Cathedral Pass, and then keeps going up... But seriously, if you're northbound, this is a pretty minor slope compared to what you've been through, so quit complaining. Sunrise High Sierra Camp is a fine place to spend the night (fresh water, numerous campsites, incredible morning spectacles) but this entire segment is full of camping opportunities. This is Yosemite, after all.The trail drops like a stone about two miles beyond Sunrise, you pass through a scorched section, then drop down through some gorgeous terrain to the back side of Half Dome and then finally through pink and green-clad crowds of increasing density to Happy Isles. A very fine feeling.