Maybe it is H, maybe it is, but i'm adamant that there is a population of them a little further north just as there might be in the GPNF area where you are talking of in general.
I don't think we are taking of a mass migration of hundreds of animals all across the South Cascades Geographical Zone. I think we're talking about little groups moving for whatever reason towards or from the Olympic Peninsula and the numbers seem to suggest that this happens, a little further north than what you're saying, in the Spring time.
This may coincide with the lack of South Cascade Geographical Zone reports in the Winter and sees animals returning to there from the Olympic Peninsula in Spring, or it might see animals going to the Olympic Peninsula for what could be mating purposes.
Small populations of any animal would have to travel fair size distances to find mates and as per what some locals in that general area have gone on record in saying, their belief due to certain factors including extreme vocalizations that don't happen at any other time of year, is that Sasquatches do mate in the general area south of the Capitol State Forest.
Of course what i've written may be well wide of the mark and we're nowhere near on the right track, but i will always side with what the numbers are telling us and will always attempt to look to breaking them down and finding genuine, logical reasoning for them. where possible