California Receives Massive Rainfall, Drought Remains

by | Feb 4, 2017 | News, page 2

Following California’s heavy rainfall, various news outlets proclaimed that 40 percent of the state has received enough precipitation to lift drought classifications. This news is easily and eagerly welcomed, since the last three years of the drought has pushed California to its ecological limits.

In this period, California has been ravaged by wildfire but is now seemingly quenched by the recent precipitation; these weather patterns are polar opposites, yet they are occurring in close time frames. These heavy rains seem like a sign that California’s drought may finally come to an end.

However, it is not quite time to start taking longer showers. University of Redlands professor and resident paleoclimatologist and geologist, Dr. Hillary Jenkins, explained that a drought this severe cannot be that easily remedied.

It is fundamental to understand that even though California may see more rain, the effects of the drought and the drought itself is far from over. Jenkins explained that the severity of California’s drought emerges from an anomalous high pressure system, called the Aleutian Low, that sits near the Pacific Northwest. The Aleutian Low, atmospheric circulation cell that casts weather patterns for North America, blocks air from passing across. Rainfall depends on that airflow. The flow coming from the Pacific Ocean is the source of the rainfall that California receives.

aleution-low

She continued that the westerlies, wind blowing from the west, meander the passage that is like a jet stream across the Pacific and bring moisture that deposits precipitation in the Sierra Nevada Mountains. But during a drought, the pressure system created an atmospheric wall, that blocked the moisture needed for rainfall. Instead, the moisture was directed all towards Canada, resulting in a large influx of rain for our neighbors to the North.

The Aleutian Low will steer a higher amount of storms during the winter months into the Pacific Northwest.

“The funny thing is, this year it is the opposite [of what we’ve seen]. Instead of an anomalous high pressure, it’s a low pressure there [Aleutian Low],” Jenkins commented. “So instead of a wall, it’s like an atmospheric river, an enhanced stream that is transporting all this moisture through wind and onto the land.”

We are seeing these results of a low pressure system from the strong El Niño year. Because of the change to high pressure from the Aleutian Low, California has recently received mass rainfall. Extreme rainfall may seem bizarre, but nothing about California drought is regular, as this is the driest California has been in 500 years.

“We are moving into a time where we can anticipate more frequent drought-like events, and yes, there have been studies that suggest we should expect more intense precipitation, and that is also true,” Jenkins continues. “The problem is we are seeing an intensification of the cycle, we should expect more intense drought and more intense rainfall. The reality is we are moving into a period of Pacific Decadal Oscillation (PDO), which is likely to encourage more La Niña-like events within the Pacific Ocean region.”

El Niño- Southern Oscillation (ENSO) is an irregular periodical change in winds and water temperatures over the Subtropics of the Pacific Ocean. The pattern has two phases described by NOAA; El Niño, the more commonly discussed of the two phases, is the warm weather phase of that causes an increase in water temperatures while La Niña describes the cooling phase. ENSO and PDO share many similarities, but they mainly differ in the the time they occur. Whereas ENSOs typically last around six years, PDOs last, on average, 20 to 30 years.

“La Niña events are likely to cause drying, especially in the Southern California region,” Jenkins said. “On average we’re going to have more La Niña-like events.” She continued, “we had a nice snap of really wet weather this year, but that is going to be atypical for what we can expect for the next 25 to 35 years.”

“The problem is the models are suggesting that we are leaning towards frequent intense precipitation, so that does mean the chances of flooding are going up,” Jenkins said, “That doesn’t mean overall we are getting wetter. We are having these events where we have so much rainfall that we can’t contain it and roads are flooded, and I think that’s really unfortunate because of flooding danger and the water will just flow off into the ocean. While as if rain is just slow and steady the ground can soak it up and we can transport it into groundwater, and that is not something that can happen in an intense event.”

In early 2014, California Governor Jerry Brown declared a state of emergency for the state’s intense drought. On Jan. 23, Brown declared a state of emergency for 50 out of 58 counties due to the intense rainfall, which led to widespread flooding across the state. These two dangerous extremes will become normal in California.

Jenkins suggests to prepare for this, “We need to move towards a regime where [this] part of the country needs to prepare for intense drought and flooding at the same time.”

The impending and atypical weather patterns will raise issues for Californian policy and infrastructure.

“On the one hand, [the state] may want to invest in having great gutters that shut off water or capture it. Or you could have these big open areas to prevent channelization of water,” Jenkins proposed, in regards to the issue of California’s unsupportive infrastructure that is prone to flooding. Because of the low levels of water in reservoirs and the desperate need for groundwater, Jenkins stated “You want to capture [rainfall] during the drought.”  

In regards to the recent rain, the San Diego County Water Authority released a public statement saying, “We have sufficient supplies to reduce the state-mandated conservation standard for our region to zero through January 2017.”

Although they encourage residents to continue their water conservation efforts, Jenkins is wary of how quickly Californian policy makers are repealing restrictions. On Jan. 1, the United States Drought Monitor recorded that parts of California were in exceptional drought. Since the heavy precipitation, they have recorded that no part of California falls under this classification. While this is cause for some celebration, parts of California remain in extreme drought. This classification is severe and should not be taken lightly.

California’s residents should not carry the mentality that their times of conservation efforts are over. Although it may be tempting for Californians to assume the threat of drought is gone after experiencing heavy rainfall, Jenkins stressed the importance of stepping beyond our personal experience and instead to understand the paleoclimatic impacts of drought.

Jenkins indicates that these floods aren’t a quick fix to California drought. Instead, California will need to receive normal amounts of precipitation for prolonged periods to restore the groundwater and reservoirs.

cali-drought-monitor

“This drought was multiyear, prolonged, and intense. And this burst of intense rain fall is not going to be efficiently captured to recover from the drought,” Jenkins said. “Has it helped? Absolutely. Is it going to restore our groundwater stores by 40 percent? No, I don’t think so.”

 

[cover photo courtesy of Halie West]

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