It is not difficult to understand an El Niño in theory, but each one plays out in reality with a good deal of variance. Considering that weather itself is generally unpredictable, it is not surprising that forecasting the patterns and potential impact of an El Niño each season is also not an exact science. The basics are as follows:
- Under normal conditions, Pacific trade winds blow over the region, typically moving from east to west, pushing the water at the ocean’s surface toward South Asia and Australia. During an El Niño, the Pacific Ocean’s warmest water moves eastward, with the strongest tropical thunderstorms shifting to the central Pacific.
- The shift in thunderstorms alters jet-stream wind patterns.
- Typically, this results in warmer than normal winters.
- A strong El Niño can cause powerful winter storms and mudslides, especially in California.
- Southern regions typically experience wetter than average winters.
How El Niño Affected California This Season
Experts were hoping that this season’s El Niño would be the answer to California’s serious drought issue. “February was incredibly warm and dry,” says David Pierce, a researcher at Scripps Institute of Oceanography. “If you look at the curves of El Niño, February to April is when we see rainy years differentiate themselves.” While California has experienced some recent deluges, by the second week of March, results were mixed. Rain drenched the Bay Area in early March, but California as a whole appears to be on track this year to record just average precipitation, despite El Niño.
The timing of precipitation varies based on the intensity of the El Niño pattern. Looking back to 1998, water temperatures peaked in November and much of the rain fell in February. In 1983, the intensity peaked in January, as it did this year. So if history repeats itself, most of the rain will fall in California in March and April. The latest meteorology reports state that 391 billion gallons of water have filled California’s reservoirs thanks to El Niño, however they are still below capacity. Weather experts and farmers still hope that the Sierra snowpack will attain normal to above-normal levels and that the state’s three largest reservoirs will reach capacity. These are the two key indicators of how precipitation is impacting a specific region or state. Only then will California be on the right path to recover from its devastating drought.
El Nino’s Effect on the Entire U.S.
NOAA’s National Centers for Environmental Information stated that the 3-month meteorological winter period of December 2015 through February 2016 set records going back to1895. Every state had above-average temperatures, with 36 states recording a top-10 warmest winter ever. The most notable warmth was in the Northeast, where all of New England experienced their warmest winter on record. However, 90 percent of this was attributed to climate change, with the remaining percentage due to the slowly waning record-strength El Niño event in the Eastern Pacific. In early March, severe storms, heavy rains, and flooding pummeled parts of Louisiana, Oklahoma, Texas, Tennessee, and Arkansas.