Nope, I'd say this is permanent. TWC's official schedule has WWCH at 9PM and 12AM.
However, the schedule says the 3AM long-form block will be discontinued (both weekdays and weekends), as well as the 11PM and 1AM blocks on weekends. This means EE will air 8-9, 10-12, & 1-4 ET weekdays, and 10-12 & 1-4 ET on weekends (PME will still air at 8PM on weekends). I wonder if Steph and Mike will host the 8PM hour of weekday EE then?
As for weekends, we may end up seeing three shifts of OCM's working from 2PM-4AM now instead of two because of the discontinuation of overnight long-form programming. Looks like this means we'll see various OCM pairings on Weather Center just like how it was pre-2005.
There's also no mentioning of ICHT and FFN from 2-4 PM weekdays, so that long-form block can't be permanent.