Very strong low-level (0-1 km) shear.
Weak 1-3 km shear, and initially weak 3-6 km shear, however the 3-6 km shear strengthened with time.
Mid-level storm relative flow that was parallel or slightly front-to-rear in relationship to the north-south moving boundary (favorable for a squall line).
A shear vector oriented at about 45 degrees vs. the north-south frontal boundary (90 degrees is most favorable for a squall line to organize).
Weakly, positive surface-based CAPE just ahead of the cold front.
A source of dry air at mid-levels that could have helped to strengthen any downdrafts that would develop.