Here is the wind data for the pertinent time period from San Francisco International:
This is not a downburst, microburst, or wind shear accident like those of the 70's and 80's!
UPDATE: 8:45PM CDT. Have been asked how I can be so sure. I was a meteorological investigator for many of the original wind shear plane crashes like Delta 191 and USAir 1016. I have done research into wind shear and I have published on wind shear in a peer-reviewed journal. Here is a blog post I wrote on the 25th commemoration of the crash of Delta 191.
You can read the entire story of Delta 191, the changes it forced in aviation and meteorology, and the subsequent litigation in Warnings: The True Story of How Science Tamed the Weather.