High Sierra Topix

I was looking at this forecast for around Parker Pass and it has nighttime lows in the upper 40s.

http://forecast.weather.gov/MapClick.ph ... tType=text" onclick="window.open(this.href);return false;

Is this really what to expect at 10800 feet in the next couple of weeks? Nighttime lows of 46-49? I ask because I have heard people caution about Tuolumne Meadows being in the 30s at night in the summer, so it surprises me to see a forecast for 2000 feet higher hovering in the 40s (which the NWS forecast has seemed to be at for a month now). I was actually hoping more for 30s since my 20 bag unzipped is still a bit warm when I sleep in 40 degree weather. I have no idea how accurate a forecast that isn't in a town would be, so figured I'd ask you guys who spend time up there.

Either way it'll be a nice break from the current 1AM temperature of 83 with 65% humidity I'm enjoying in South Texas right now.

Next week is going to be close to as hot as it gets in Yosemite during the year, which normally happens in July. The low 40s is probably a little warmer than normal for Parker Pass in July because the drought is so bad this year that most of the snow is long gone at those altitudes, and the snow is very helpful for driving the night temperature down to freezing. At the pass or any other exposed area above the tree line, you may experience local winds periodically that effectively lower the perceived temperature by several degrees (wind chill factor), so you may still get a chance to really use your gear. It is always better to be prepared for more cold than you expect, since the forecast is really just an educated guess. I cannot begin to tell you about all the snow storms I have lived through on summer/fall trips that were not in the forecast when I started my trip.

If it does not get very cold at night, you will be fried during the heat of the afternoon sun and need extra water and energy, so either way you will have a challenge.

Just unzip your bag all the way and use it as a blanket, leave all your vents and doors
open, and do not put you fly on your tent if you have that option.
The weather is fickle in the Sierra, have experienced snow in every month, so anything
is possible, especially a couple of weeks out. 30's as an average at that elevation is
more towards spring/fall.

My rule of thumb is that in stable weather conditions I wouldn't expect a frost at Cottonwood Lakes when the daytime high in Lone Pine is above 90 degrees (i.e. most of the summer). At Soldier Lakes last July (10800ft) the nighttime low was mid to high 40s and the daytime high in the low 70s, but that was almost the hottest week of the year in Lone Pine (daytime high was 104). I was happy because I forgot to take my jacket/sweater and only had a long sleeved T-shirt.

Up in the Emigrant wilderness, not too far north of Yosemite, we had nightime lows in the 50's about a week ago at 8600 feet, and the upper 40's at 9500. So it can definitely be in the 40's at 10000 feet sometimes. And then it can drop down into the high 20's.
Personally I don't usually adjust my gear for the short-term forecast, I just have my standard summer in the Sierra gear and I bring that every trip. It's so changeable that I just don't trust a forecast past 2 or 3 days, and it might be fairly warm but windy as all get out, or something like that.