The Younger Dryas ended circa 11K BP; the Lake Missoula flood which produced the Channeled Scablands may be of that earlier date (I found it hard to nail down on the web, one proposed date is 14K BP), but that water went to the Pacific. :')
from Wikpedia:
The prevailing theory holds that the Younger Dryas was caused by a significant reduction or shutdown of the North Atlantic thermohaline circulation in response to a sudden influx of fresh water from Lake Agassiz and deglaciation in North America. The global climate would then have become locked into the new state until freezing removed the fresh water "lid" from the north Atlantic Ocean. This theory does not explain why South America cooled first.
I'm also reading After the Ice by Stephen Mithen, an excellent account of the Pleistocene/Holocene times. It reads like a novel. Good chapters on the day to day lief of humans in various post ice age settings, as the world grew warmer and wetter, or dryer, in some cases.