If I use the

player.forceav carryweight ###

console command does it permanently force the weight to always be that number or does it still increase with stamina and such and simply set its current value to the specified number?

I think it continue to increase.

If you want other bonuses like stamina to apply use modav instead of forceav.

Never use forceav as it adds a permanant modifier to the stat in question. Your carryweight will still increase normally, but you'll never be able to get rid of that modifier without further use of forceav to account for the altered stats.

In short, use modav as was pointed out - far safer.

Thank you, I appreciate your replies. modav will work perfectly

I always mod the carryweight and yes it does increase with stamina.