Hi, SS ...
Do the layer thing as Donna suggests. You might also want to take a "wrinkle suit" ... those flannel-lined pants and jacket that come already wrinkled for your packing convenience. A hooded, lined anorak jacket would also be good.
Don't pack a lot of sweatshirts. Buy 'em as you go along, don't spill anything on them and you can give them to your friends and family when you return.
Also a poncho. They are great insulation! And they fold up really small. You can grab them for a few dollars at your local discount department store. Umbrella, yes.
I recommend "glitter gloves" which you can find at a ski or sporting goods store. Wear them under another pair of gloves. Plain cotton work gloves serve the purpose. The point of the glitter gloves is that you can still use your camera or binocs after removing the outer gloves.
Don't forget your sunglasses !!!