Mostly, I find writing with an outline helpful. It keeps me from having to stop writing and figure out what comes next and why, and how it should fit into the larger plot.
I knew I didn't have enough plot for Wharf Rat, but I didn't expect what happened yesterday. Three days into NaNo and I slammed to a dead halt. No clue what comes next. I haven't written a word all day. (Tweets don't count.)
The problem is that I wrote a paragraph that would launch a subplot, which I need. Usually when I do that, I can come up with something on the fly, jump right in, and go back later and backfill necessary scenes to make the subplot fit in. But this time...nothing. Crickets. Dog barking in the far distance.
So now it's 9:20 pm and I spent most of the afternoon baking (pumpkin pies that turned out terrible, blueberry tarts that turned out terrible, rice pudding that turned out wonderful thank gawd) and most of the evening browsing membase (which was funny at first and then just depressed me). And I still have to write something.
I guess I'd better skip ahead and write a scene I know I'll need. I hate doing that. I feel like I'm cheating.