Meteorologists have been warning the public for months that this year’s El Niño would likely be one of the strongest on record, and the recent wave of storms flooding California has so far proven that to be true. But what you probably haven’t heard in the news is that El Niño isn’t the only climate phenomenon at work — the heavy winter weather is also getting a boost from the less well-known Madden-Julian Oscillation, or MJO.
If you’ve never heard of the MJO before, you’re not alone. It’s a cycle of tropical winds and rain that moves between the Indian and Pacific oceans every 30-60 days, usually resulting in heavier rain and snow along the West Coast during winter. When combined with the El Niño phenomenon, this effect is even more pronounced than normal.
Unfortunately, what this means for the West Coast and the rest of the US isn’t exactly clear right now. Scientists don’t have a lot of data on the combination of the two weather phenomena, so all they’ve been able to offer at the moment are a best guess. It’s likely that heavy storms will continue to batter California in the coming weeks, with unusually cold temperatures hitting the eastern US in mid to late January.
With the MJO enhancing the effects of El Niño, you could be forgiven for assuming the weather patterns are relatively similar. However, there’s one big difference between the two: El Niño creates a warm sea surface along the Pacific Ocean and remains stationary for several months, while the MJO moves back and forth across the ocean in a matter of weeks. So once the MJO has passed, a slightly less stormy El Niño will probably remain in effect until Spring.
Images via David Prasad