my son is in 7th grade and has the same issue. His IEP states that the teacher has to break these larger assignments up into smaller "chunks" with due dates. First the outline, then paragraph one, etc. It really helps because if he doesn't have things correct at that point he can just redo that part instead of having to start all over again. It also helps my son to do his papers on the computer instead of actually writing a rough draft. That way it's easier to delete and insert things without drawing little arrows and having to rewrite an entire paragraph just to fit a few words in or take a sentence out.

My child with ASD is little but I really like "The Paragraph Book" series by EPS for teaching how to write a coherent paragraph. The teacher's manual is geared towards classroom use so I didn't bother getting it after the first book. http://eps.schoolspecialty.com/products/details...

How about making an outline using different color index cards for each disaster. Hurricanes could be on blue index cards b/c they usually form over water. Tornados could be another color, etc. Hope this helps. :-)

My son is 14 and in ninth grade and still struggles in the same way. Fortunately he has an IEP so he has some accommodations.

For his composition class last semester he had one longish paper to write. He chose the topic and did the research for himself. Like your son the problem came with the actual formation of paragraphs that stayed on topic and logically followed each other. His teacher helped him write an outline and I used that to help him write the paper.

When I say I helped him this is what I did: First I told him he needed an opening sentence, he came up with one that he verbally told me and I wrote it down. Next I said he had to state his topic sentence. He did and I wrote that down. Then I told him to come up with three our four more sentences to support his topic sentence. We continued this way for the entire paper. I told him what type of sentence he needed, he came up with one and I wrote it down. I guess I kind of pulled each sentence out of him.

Probably not the best way but the ideas and sentences were his. Also we followed the outline the teacher helped him with. I know that the organization was mine but at this point that is the route we took.

My daughter also has problems with writing. She is 18 and can't get beyond one or two sentences and has trouble organizing her thoughts. She gets help in school from teaching assistants but I wonder how much they do it for her.
When she gets writing assignments I try to help her write an outline to organize her thoughts. The Big 6 looks very good.