Forecasters predict a well-above-average Atlantic hurricane season

Top forecasters from Colorado State University predict an exceptionally active hurricane season starting June 1st, marking the most active projection ever made in April. Typically, a year sees about 14 tropical storms, with seven becoming hurricanes. Last year, despite moderate forecasts, there were the fourth most named storms on record. This potentially prolific season is driven by record high Atlantic temperatures and the impending La Nina.

What record was set last year despite a more moderate forecast?

What factors are driving the potentially prolific hurricane season?