> I've been comparing the temps recorded at CWD (~10k ft elevation) with the forecast for the area.
Which forecast are you looking at?
I've been using forecast.gov and mountainforecast.com. For example, for the low temp Fri night (Sept 26):
forecast.gov prediction @ 10,000 ft: 36 degrees
mountainforecast prediction @ 11484 ft: 28 degrees
CWD observed low @ 10150 ft: 23 degrees
The guy that took the photos I posted said it dipped into the teens Friday night at the Cottonwood Lakes where he camped.
I follow the -4 degree for every thousand feet rule and it's been close. Based on that, you should expect the temps in your predictions for Langley if not even lower due to wind chill factor.
EDIT:
You might find useful-
http://mtsanjacinto.info/viewtopic.php?f=11&t=4938 I believe I've read 3-5 degrees per 1,000 ft depending on humidity and cloud cover. I usually go with 5 degrees.
Thanks - Sounds like he was on the trail at the same time as the hiker that took the photos above.
A friend of mine has a similar story from Rabbit Peak a couple of years ago. He joined a group for the hike, going with people that had completed the hike several times. They got stuck in a bad storm. The leaders were 'map & compass only guys (oddly enough they left them at home),' but due to the very poor visibility, my friend ended up leading the group off the mountain using the 'backtrack' feature on his GPS. It was a good reminder to be self-sufficient, even when going with experienced hikers.