California, United States

A series of atmospheric rivers slammed California in the United States as the forecasters issued warnings against severe storms, strong gusty winds, heavy downpours and a risk of flash floods.

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The atmospheric river storm, known as “Pineapple Express” battered the state and left behind a trail of damage, flooded roads and fallen trees. It also caused major traffic disruptions.

The storm is also likely to dump heavy snow over the Sierra as well as the Intermountain West region.

Here’s all you need to know about California's current weather patterns and the impact it is likely to have in the western part of US.

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What is an atmospheric river?

The atmospheric river systems, also called as “rivers in the sky” by the National Oceanic and Atmospheric Administration, refer to the long streams of moisture present in the atmosphere.

The atmospheric rivers which affecting western US are getting supercharged by the water vapours evaporated off the Pacific Ocean and are being moved from the tropics or subtropics by other weather systems.

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Also read: El Nino could make 2024 hotter than record 2023

An average atmospheric river can carry the amount of water gushing from the mouth of the mighty Mississippi River. The strong ones have the capacity to hold 15 times that amount.

After the atmospheric river makes landfall, it releases the moisture as rain or snow depending on its size, intensity and timing. The resultant storm has the potential to be extremely beneficial or highly destructive.

What is a Pineapple Express?

The storms which have been hitting California in the current week are part of the “Pineapple Express” system, which is one of the types of atmospheric rivers.

The storms, which have been named on the basis of their origin around the Hawaiian Islands, are generally strong systems and have unleashed torrents of precipitation after hitting the west coast of the US and Canada.

As per the National Ocean Service, the Pineapple Express has the capacity to dump as much as 5 inches of rain on California in one day.

Why are atmospheric rivers making people anxious?

The storms this week have become a great concern for the officials and residents, partially because of their timing.

California was battered by a similar kind of brutal atmospheric rivers last year which had drenched the state and unleashed historic levels of rainfall which caused landslides, road closures and urban flooding.

Although the current winter has not witnessed a similar level of rainfall, they have already seen various instances of severe flooding.

These storms have been incredibly dangerous and destructive, scientists have warned that they are just a hint of what is likely to come next.

Watch: UK hit by more than 600 flood warnings after storm Henk downpours

Ahead of the storms this week, unsubstantiated posts went viral on social media which expressed the anxiety of people over the chances of weather getting a lot worse.

Can the atmospheric rivers leave any positive impact?

Even though the atmospheric rivers are potentially dangerous, they are incredibly important for California where they get welcome from water officials who are still navigating ways to emerge from prolonged drought.

California, even with the wet weather, has been lagging in snowpack this year and experts have been hoping a heavy dusting can help them get closer to historic averages by the end of the wet season in April.

The snowpack is important for the water supply of California, which acts like a water savings account for the state for the rest of the year, as it melts slowly and flows into soils, streams and reservoirs when drought hits the state.

Nearly a third of California’s water needs in an entire year is fulfilled by the snowpack.

How has the climate crisis contributed to atmospheric rivers?

The climate of California has dramatically vacillated from wet to dry for a long time, but models have demonstrated how these shifts will take place with even greater intensity amid global warming.

As per the study published in Science Advances, the atmospheric rivers are slowly becoming more likely to come in sets which can increase the economic damage by four-fold.

According to the scientists, the artificial rains, which are supercharged by more moisture that comes off the Pacific as ocean temperatures increase, can also become more severe and raise the risk of more floods across California.

As the temperatures increase, the state is more likely to receive precipitation in the form of rain rather than snow, which can increase problems for the water supply of the state.

(With inputs from agencies)