We did an overnight, camped just below the pass.
Current conditions:
road: bad for ~4 miles. Saw a sedan in the parking lot. Not sure how scraped it was.
snow: below the pass, plenty snow, covering some trail. But overall, not difficult to figure out. Yes, always download a GPS map. From the pass to the lookout, clear of snow, lots of heather blooming. From the pass down to the lake, no one went. I went down to the camp site in between, no other footprints whatsoever. Lots of snow with rocks sticking out. I didn't go down to the lake proper. The lake is partially covered with snow. From the pass to the north Hidden Lake Peak: all rock scramble. I didn't see anyone else going there either.
flowers: quite good on the open slope in the south fork Sibley Creek valley. The slope is in full sun (facing south).
water: a lot of water, even on the open slope. Maybe later in the summer these little creek crossings would dry up.
mosquito: quite a lot in the forest and on the flowing slope. Not bad at all on the rocky traverse higher up and on the ridge. Some flying ants on the top rock next to the lookout.
Photos (more later)
1) inside of the lookout
2) land slide at the creek crossing
3) flowering slope
4) going up to the lookout
5) pano of the lookout
6) going down towards the lake
7) the summit of Hidden Lake Peak: (north of the saddle, opposite side of the peak where the lookout is) pano view to the east and south, pano of the top rock