Originally Posted by
bedrock
I don't know anything about the CRJ, but cold soaked fuel occurs when you have been aloft for some hours and the fuel drops to very cold temperatures. The danger in this is that the wing becomes very cold as well and even slight moisture will form ice instantly all over the wing. Usually there is a mechanism to keep the fuel from getting so cold that there is any chance of ice actually forming in the fuel itself.
Chapter 2 - Theory and Aircraft Performance - Transport Canada
I see it all the time on our transcons in the Airbus. It's just the bottom of the wing that gets frost. It quickly goes away once fuel is pumped in and you sit for 30 mins.
The CRJ limitations section mentions this, allowing for frost on the underside of the wing.