this far, I only manually add the weather from http://wttr.in/?FT1q (the F, T 1 and q url params can be read on http://wttr.in/:help). I then give 5 spaces before the region name and 2 spaces before the weather ASCII image to make them quote
I use the CSS for markdown from [[A CSS to embellish *MultiMarkdown* rendering]]
I might improve the above AppleScript sometime later, but currently quite busy myself. Do let me know if you’ve found the solution yourself! I will do the same 