Some places that sell them are: burlington coat factory,nordstrom, old navy, jc penny, catherines, and target. Its always a good idea to call and see what sizes might be available first.
Old Navy has a great selection of plus sized clothing, including outerwear, and they are located pretty much everywhere. Also, Walmart carries plus sized clothing and they sell outerwear as well.
Lands End, which is owned by Sears, has very cute plus sized outerwear. You can go to your local Lands End store or visit landsend.com in order to view the plus sized parkas and other cute outerwears.
Many of the outerwear options offered by Columbia are available in plus sizes. The Columbia brand website would probably be the best way to find the outerwear that suits your daughter most.
Many mainstream retailers like Walmart, Target and Macy's carry plus size clothing, including coats. In addition, there are various stores that sell only plus sized clothing such as Torrid and Lane Bryant which also carry outerwear.
No, I do not think that K-Mart sells trendy outerwear for professionals. To find trendy outwear for plus sized professionals, you should try Kohls or JCPenny.
When buying plus sized clothes online, you can choose plus size specific retailers like Lane Bryant and Avenue. They have a great selection and carry many sizes. Other stores that may not carry plus sizes in store will offer extended sizes online. Look at Banana Republic, American Eagle and The Gap.
Macy's does offer a relatively large selection of plus sized women's clothing. They carry clothing lines like J Jill that offer very stylish clothes for the plus sized.
You can get plus sized work out clothing for women at Walmart,Target,and Kohls among other retailers.
Places like Overstock, Forever 21, Torrid, and Nordstrom not only offer plus size options in terms of dresses for plus sized women, but they also offer leopard print dresses in plus sized sizes.
A great store to look at when shopping for plus sized swimsuits is SwimSuitsForAll.com. This site provides suits for plus sizes in fashionable style. http://www.swimsuitsforall.com/
The easiest way to find wear to buy plus sized Columbia outerwear is by using the site Bizrate that provides prices and links to stores selling them. Finding them cheap and authentic would be your hardest hurdle to cross since most name brands have many knock offs.
Sear's is a good source for plus sized clothing. Check out their website at www.sears.com. They offer a wide variety and at reasonable prices. They are also one of the few retailers who still have a storefront presence.