penumbra

Hi, New to Oregon and trying to find a suitable bivy/sleeping bag combo. My yearly goal is to do 3-4 day backpacking trip about twice a month, with a few Mt. Hood trips thrown in for fun. However, coming from sunny southern california, my gear is targeted for the mild and dry weather and maybe woefully underprepared for the infamous moisture-laden/drenched areas of the PacNorWest. I want to first make sure my shelter is adequate. I have a Integral Design Unishelter EXP E-vent bivy/tarp setup and want to pair that to a synthetic bag. While I have down bags (Mountain Hardware Ghost SL -40F bag, and a Sierra Design +32F 600 fill bag), I want a workhorse syn-bag that can withstand the condensation of a bivy, the moisture intrusion of heavy rain while setting up bag and bivy or midnight bathroom trips, or even just jamming my wet clothes (excluding shell) into my bag to dry. I have never gotten my down bags wet, and don't think I will with careful planning. However I like the additional insurance just in case I did screw up in PNW. Such as day hikes away from camp and returning to a drenched bivy/sleeping bag because I forgot to zip it up completely in heavy rain, or setting up camp not realizing my bivy has a puncture and letting in rain/runoff, etc. That said, what will be a general purpose synthetic bags that I can use for Hood and surroundings during fall/winter/spring? -20F to +15F bags? I'm currently looking at TNF Tundra -20F syn-bag with Polar Guard Delta for $150. Any other suggestions? Thanks, Frank