I may be well able to help you there.
Mountain Designs parka in XL Good to -25/-30 C when active Lower when properly layered
viewtopic.php?f=13&t=22956Also if you don't want to buy I could hire it too you by refunding most of the purchase cost when you get home and send it back to me.
Rates negotiable
Won't be going to Nth America this Christmas so I won't be using it until next year
You will need an over-parka/ windproof anorak to protect it tho