I am writing from the UK (Europe) where we don't have most of the detailed US aviation weather services.
As a very general question: do these "area icing" charts mean very much in practice?
Obviously if you are high enough to be in VMC, then you won't pick up ice. And if you are in IMC, between 0C and about -15C (nonconvective cloud assumed) then icing is IMHO a certainty eventually, so one should not fly in such conditions on a long enroute section unless appropriately de-ice equipped and, if significant convective (in this case embedded TCU/CB ) weather is forecast, radar as well.
I have seen "icing hazard" charts for Europe, most notably
here (under Flight Hazards), but they just seem to correlate with where one would obviously expect convective conditions by taking one look at any chart that shows fronts e.g.
here.
In between fronts that are say 200nm apart, I don't see how one can reliably forecast where one parcel of air is going to have more supercooled water droplets than another parcel lying say 50nm away. And on the actual location of a front (which is usually pretty obvious from one look at a satellite image) you could draw an area showing an icing hazard and be right 90% of the time
Does the above make any sense?