You would think Himalayan trekkers would all carry something like this: https://www.youtube.com/watch?v=al4UUSAd5yQ
‘Live and learn or you won’t live long’! http://www.lifesystems.co.uk/products/outdoor-survival/4-person-survival-shelter.html
I am taking the two person model (350 grams) to EBC in November 2016.
The new breathable ‘Escape Bivy’ (http://www.adventuremedicalkits.com/survival/survive-outdoors-longer-escape-litetm-bivvy-1.html) @ 157 grams is surely a must in your day pack along with (eg) something like this to keep your dry and warm (http://www.adventuremedicalkits.com/survival/survive-outdoors-longer-survival-poncho.html) @ 65 grams. Surely a small price to pay (both in weight and dollars) to save your life.