Why do neutral years in the La Nina/El Nino cycle produce more serious storms?
Keep in mind the La Nina/El Nino pattern is a cycle averaging 3 to 7 years (meaning there's a lot of variation from one cycle to the next!). Our La Nina pattern is fading, and we're moving rapidly to the neutral phase of the cycle. Statistics do show 'major' storms are most frequent in 'neutral' phase years. At this point, the statistical relationship does seem valid, but there's not enough data to permit conclusions. We do know that El Nino patterns feature a split jetstream, which would work against allowing intense lows to persist, and La Nina patterns tend to block major lows from advancing northeastward from the tropics. But this matter needs more study.