Photo by Mary O’KEEFE
Heavy rains downed power lines in the 2400 block of Montrose Avenue on Tuesday interrupting
electricity for several blocks.
Living up to the hype, El Niño arrived knocking out power and drenching the foothills.
By Charly SHELTON
It finally happened. The long-awaited “Godzilla El Niño” has arrived. For weeks leading up to these first storms, hitting the Southland between Tuesday and Saturday, there has been wacky weather with storms and flooding across the Midwest, abnormally warm temperatures in the east and tornadoes up and down Tornado Alley. So where is this crazy weather from and what does it have to do with El Niño?
“Well there are two things that are happening here over North America,” said Bill Patzert, climatologist at JPL. “There is a strong subtropical jet stream coming up out of the Central Pacific. This jet stream is aimed at us, and this is what brings us in an El Niño year – uncommonly high temperatures in the equatorial region of the Pacific causing massive, water laden clouds, which are then funneled up to the Southwest via a jet stream where it cools and dumps all of its rain.”
Patzert explained that the second aspect is the cold air, noting that for the last two weeks it has been colder on average in L.A. than in New York City.
“An unusual amount of storms over the north Pacific is forcing a mass of cold air down on us in the Southland to give us the coldest Christmas we’ve had in a while,” he said. “As the cold dry air moves down from the north, it is diverting the subtropical stream off to the east and soaking the Midwest. When this combination of cold air and warm air meet in Tornado Alley, the masses of air blow quickly across the plain and tumble over each other, with the air rising and falling as they move. Then, with the right speed and wind conditions, it can be tilted up by a hill and turned into a tornado, which is why we have seen those sprouting up here and there across the Midwest as well.”
Into January and February, the pattern will become more zonal meaning that a series of storms is expected coming from north of Hawaii out of the west.
“Ultimately heavy rainfall will soak the southern tier of the United States, and the northern tier of the U.S. will get less volatile and milder,” Patzert added.
On Tuesday, this new pattern kicked in. With 3.3 inches of rain reported in the Crescenta Valley on Tuesday alone, with two more storms touching down on Wednesday and Saturday, this El Niño is starting with a big, wet bang. Patzert warned that although getting so much rain sounds like a great idea during a terrible drought, it could be dangerous as well.
“There’s a famous saying: great droughts end in great floods,” Patzert said. “The United States has some of the most volatile, punishing weather of any country on the planet. It’s mostly part of our geography; for instance 80% of all the tornadoes that happen in the world happen in the United States. Not just here in the west but across the country flooding is a big part of our history. Here in California I always say there are four seasons: drought, fires, floods and earthquakes.”
The problem with getting so much water after getting so little water is that the soil adapted to the drier conditions. With so little water falling into local mountains and riverbeds the past several years, the ground is very dry and compact without the room between grains of soil and sand that water would usually occupy. Just a little bit of water keeps the ground looser and therefore able to take in more water. For example, spread some sand in a layer about an inch thick across the bottom of the shot glass, pour a bit of water in and flip it upside down over cheesecloth. As the water strains out of the sand it moves each of the little grains closer together and makes it more compact. After that sand has completely dried, it will fit together more tightly and form a little cake. Doing this on a large scale and allowing it to dry over hundreds of years results in what most of California is built on – sandstone.
On a much more minute scale, this is what is beginning to happen to the sand and soil in the foothills. Although not sandstone yet, the grains of sand and soil fit much closer together and when water tries to seep in it can’t saturate as much as it used to. With the current amount of water flowing into the ground, it won’t all be absorbed and a lot of it will run off, causing floods and debris flows.
“There’s good news and bad news,” said Patzert. “We’ve concreted and put an awful lot of flood control infrastructure in place in Southern California. A good example, of course, is the L.A. River, which is 51 miles of concrete connected to 2,600 miles of storm sewers. This essentially protects us from large-scale regional flooding like we’re seeing in the Midwest. But the bad news is that we’re surrounded by mountains to the north and mountains to the east and below that are the foothills, which are set at the end of arroyos and canyons. As the waters come out of the mountains, [we’re] prone to floods and mudslides. Everything below that is a floodplain – L.A. is a floodplain.”
Not all is doom and gloom though. With proper home maintenance and inspection of car tires and wiper blades (remember that headlights must be manually turned on when wipers are on), the El Niño may pass homeowners by without doing damage. Because of the drought, getting this much rain is definitely helpful. Though one massive El Niño year is not enough to completely end the drought – California is four to five years deficient in water collection –it will go a long way.
“If everybody uses a little common sense, this is a nice down payment on [ending] the drought,” Patzert said. “It’s not a drought buster but it’s a nice down payment.”
To find out what you can do to get your home and property ready for the storms that are expected to hit from now to March, visit elninoready.org and check CVWeekly.com for previous stories about El Niño preparedness.