Check out the IFR alternate minimums for Des Moines.
The way I read it, you can use the ILS, LOC, VOR/DME approaches for alternate minimum planning even WITHOUT local weather being available.
Why is this the case for just these approaches, whereas local weather IS required to be available for the GPS RNAV approaches?
The FAA seem to make it clear that alternate airport local weather IS required for a particular approach to be considered for the purpose of alternate minimum planning: "Not all airports can be used as alternate airports. An airport may not be qualified for alternate use if the airport NAVAID is unmonitored, or if it does not have weather reporting capabilities." (From the Instrument Procedures Handbook).