What could cause cold weather electrical problems, after normal startup? on 2007 Ford Five Hundred

On 2 of the coldest mornings this year (~20F), I've started the car to warm it up. After the car started normally, I noticed that nothing electrical either on the dash or head lights would come for the first ~5 minutes. Eventually, power would start flickering in such short durations that it was almost un-noticeable, and then in longer and longer intervals until continual power. Any ideas?

Asked by for the 2007 Ford Five Hundred
poss relay sticking open under those conditions