It turns out that "Kitakata" can either designate the regional soup style of the City of Kitakata, or simply the particular type of noodle associated with that soup style, and Tanpopo was using the term in the latter sense. According to the Rameniac blog, Kitakata ramen features
"...a noodle made largely from mountain spring water. A significant amount of water is added to the noodle, which shapes up flat, wide, and curled. A tactile sensation of slurping and the chewiness are the key features of Kitakata ramen noodles."
Tanpopo is a hectic but cheerful venue which fits my imaginary picture of what a popular ramen-ya should be like, and has a long and varied menu of both ramen and sides. I'll be back.
Where slurped: Tanpopo Restaurant, 1740 Buchanan St San Francisco, On the Buchanan Street Mall.