Step 2

Step 2) Take another hour and expand that sentence to a full paragraph describing the story setup, major disasters, and ending of the novel. This is the analog of the second stage of the snowflake. I like to structure a story as "three disasters plus an ending". Each of the disasters takes a quarter of the book to develop and the ending takes the final quarter. I don't know if this is the ideal structure, it's just my personal taste.
If you believe in the Three-Act structure, then the first disaster corresponds to the end of Act 1. The second disaster is the mid-point of Act 2. The third disaster is the end of Act 2, and forces Act 3 which wraps things up. It is OK to have the first disaster be caused by external circumstances, but I think that the second and third disasters should be caused by the protagonist's attempts to "fix things". Things just get worse and worse.
You can also use this paragraph in your proposal. Ideally, your paragraph will have about five sentences. One sentence to give me the backdrop and story setup. Then one sentence each for your three disasters. Then one more sentence to tell the ending. If this sounds suspiciously like back-cover copy, it's because . . . that's what it is and that's where it's going to appear someday.