Punctuation when writing out a numbered list with the words "one", "two", etc

Question

I am unsure of the proper way to write out a numbered list when the individual numbers "one, two", etc. are spelled out. Here's an example of what I'm talking about:

"The plan failed for three reasons: one, nobody checked beforehand to see if the zoo was open on Sundays; two, my mother forgot to put mayonnaise on my sandwich again; and three, Alec Baldwin showed up."

I'm almost certain I've committed some punctuation atrocities here. What is the proper way to write this paragraph?

Answer 1

From Purdue:

Use semi-colons between items in a list that already involve commas.

- I have lived in Chicago, Illinois; Kansas City, Missouri; and Omaha,
Nebraska. 
- The sweaters I bought today were purple, blue, and green;
yellow, white, and red; and pink, black, and grey.

From the APA Style Blog:

Semicolons

This gets more complex when an item or multiple items in your list already have commas. In these cases, separate the items with semicolons:

Each child was seated at a separate station and given the following
plush toy or toys: an elephant, which all children saw in the previous
experiment; a kangaroo, which only half of the children saw in the
previous experiment; or both the elephant and the kangaroo.

From these examples, it appears that your usage of semicolons to delimit a list that includes commas is correct.

If you are specifically referring to the usage of numbers within (although your sentence looks fine regardless), see this question.

Edit: I also found an MLA resource here (look for the parts on semicolons).