Originally Posted by exAC

Even more complex than that.

These are enroute alternates. If SEA, PDX, SFO are all forecasted to be fogged in then the flight could need to hold enough fuel to divert to LAX or even further inland like LAS. There would need to be enough fuel onboard to divert to these places up to half way across to HNL.

It is much more rare not to e able to plan a suitable airport somewhere in the islands.