What size yarn is called for?` If it is fingering yarn, you could use sock yarn that's machine washable. I don't use wool, so I am not much help here.

I can think of a couple of yarns with long colorways. First is Kauni. Go to www.knit-purl.com and search for Kauni - they show small photos of the colorway changes. There was also a KAL for the Kauni cardigan and if you search on Ravelry you can find lots of knitters who have used this yarn. Kauni is not superwash.

Jojoland sells some long colorway superwash yarns, but I think it's in fingering weight. I have some Jojoland lace weight and it's lovely.

Some of the Noro yarns might be nice for your jacket.

Your jacket pattern is very pretty. Have a good time making it!

Tommeca -
I just fell in love with that pattern. I have made some squares with different shades of blue wool blend yarn. It is beautiful using the soft wool blends. Works up very easy. I'll check out the sites. You mention Noro and Jojoland are these sites too or can you buy this in stores. Do you know the names of the stores.
Thanks for the suggestions.

Claudia Hand Painted Short Sport looks like it's pretty close to what you want -- 100% Merino Wool, 50 grams/112 yds, 5-6 sts/inch, machine wash delicate. It comes in 11 colorways.

It's less than half the price of the LaLana Wools yarn -- $11.75/skein. Not cheap, of course, but not bad at all for a hand painted yarn.

You can order it online at the website below.

Here is a link that might be useful: Claudia Hand Painted Short Sport Yarn.