I wouldn't bother with the poncho, a good waterproof coat and trousers would be better and you will get hot very quickly as the climb up is er? a steady one?? the need for more layers is essential when you get up into the wind, i think with just a base layer and a water/wind proof wind the wind chill starts cutting into you thats when your outer skin starts to get extremley cold and you risk your core body temp to reduce, so a couple of fleeces ready to put on before the wind starts to cut you in half. I was up that way a week or 2 ago and there looked like a good layer of the white stuff up there,so i would really watch your footing its a long way to drop if you come a cropper!
I'm no expert but have been up several times by several different routes and the weather and terrain can cause difficulties for the inexperienced, so if it starts to look dodgey look for the quickest and easiest way off,i would say straight down to storey arms. But most of all enjoy it!!!
The dog lives for the day, the hour, even the moment.