El Niño means tropical Pacific is warmer than normal, which improves chances that typhoons will form…typhoons on both sides of the equator are helping to reinforce a big burst of westerly winds along the equator. These westerly wind bursts are a hallmark of El Niño, and help push subsurface warm water toward the coast of South America. If enough warm water butts up against Peru, the normal cold water ocean current there can get shut off, exacerbating the pattern.
Exactly how this all gets kicked off is an area of active research, but it’s clear that big El Niños need deviant trade winds to maintain the feedback loop. During especially strong El Niños, like this year’s promises to be, the trade winds can sometimes reverse direction—and this week’s off-the-charts wind surge is at record-strength for so early in an El Niño event.
PS Typhoon Soudelor hits Taiwan reported rainfall 1.5m in 48 hours – ouch!