A monster El Nino may be on the horizon

A new forecast from NOAA’s Climate Prediction Center is that a “super El Nino” is likely late this year, perhaps starting in October. The odds are about 65% that this new warm water phenomenon will be one of the strongest in recorded history as sea-surface temperatures would be at least 3.6 degrees above normal. Oceans waters are also warming faster than originally anticipated and scientists anticipate a new El Nino will be declared at any time between now and July.

As I mentioned several months earlier, a strong El Niño occurs when unusually warm ocean temperatures develop in the central and eastern Pacific Ocean, altering atmospheric circulation and weather patterns across the globe.

In the United States, these changes are especially noticeable during the winter months. For example, the northern United States, including the Pacific Northwest, northern Plains, and parts of the Midwest, typically experiences warmer and drier conditions during a strong El Niño as the northern polar jet stream, the one that has a high influence on our weather, will often weaken and move northward. The winter seasons in these regions, including North Idaho, are often milder than usual with reduced snowfall.

By contrast, the subtropical jet stream tends to strengthen and move northward. As a result, the southern portions of the U.S. from Southern California eastward across the southern Great Plains and into the Southeast, will often experience much wetter than average precipitation. This pattern can be beneficial in drought-stricken areas, particularly in California, where increased rainfall would help replenish reservoirs. However, excessive precipitation can also lead to flooding, landslides, and infrastructure damage, especially when storms are intense or prolonged.

One of the strongest El Niño events in human history occurred during the late 1880s. Scientists often describe it as a “monster” El Niño because of its powerful effects on weather around the world. The strength of the 1877–78 El Niño was reconstructed using ship records, rainfall data, and coral studies.

The event caused major changes in rainfall and temperature patterns. California experienced intense winter storms, flooding, and mudslides as Pacific storms moved farther south than normal. Rivers overflowed and transportation systems were damaged by heavy rain and flooding. By contrast, severe droughts were reported in Asia and Australia, while parts of South America experienced destructive flooding.

The 1938 Southern California flood was one of the most destructive natural disasters in the history of California and remains a landmark flooding event often compared to modern El Nino events. In late February and early March 1938, a series of powerful Pacific storms struck Southern California after weeks of earlier rainfall had already saturated the ground. Rivers rapidly overflowed across Los Angeles, Orange County, Riverside County, and surrounding areas. Across the Inland Northwest, moisture totals were about 70% of normal for 1938 and 1939.

The 1982–83 El Niño was one of the strongest of the 20th century and caused more widespread flooding, coastal erosion, and mudslides across Southern California. Torrential rain overwhelmed rivers and flood channels in places such as Los Angeles, Orange County, and San Diego. Roads collapsed, homes were destroyed, and coastal highways suffered severe erosion. The storms caused billions of dollars in damage and led to major improvements in flood-control infrastructure afterward. During this El Nino, total precipitation was slightly above average, but snowfall totals were slightly below normal.

The 1997–98 El Nino event is often considered the benchmark for modern flooding in California. Southern California experienced repeated powerful Pacific storms from late 1997 to early 1998. In Orange County alone, flooding caused tens of millions of dollars in damage. Some areas received over a whopping 7 inches of rain in a single day. During this time, the Inland Northwest had near-normal precipitation, but less than half of average seasonal snowfall.

The big El Nino event in 2015-16, which is widely considered to be the strongest ever observed, triggered periods of intense rainfall, flooding, and mudslides across Southern California. Heavy storms in January 2016 flooded roads, damaged homes, and triggered evacuations in foothill communities. This El Nino had the highest sea-surface temperature anomaly with readings warmer than normal by approximately 5 degrees Fahrenheit. There is a chance the one expected late this year could rival or surpass that anomaly. Precipitation was close to normal at this time across the Inland Northwest, but snowfall was about 80% of normal.

The most recent El Nino occurred from May 2023 to March 2024. Scientists state that the phenomenon was at least partially responsible for 2024 being the hottest year ever recorded on the planet. They are also suggesting that if the upcoming El Nino is super strong, then 2027 may turn out to be Earth’s hottest year.

In terms of our local weather, scattered showers and thunderstorms are possible into early June, but high pressure is expected to rebuild across the northwestern portion of the country later next month. With the developing El Nino, the upcoming summer across the Inland Northwest is expected to be drier and warmer than average. Wildfire predictions for the northwestern U.S. are for “above normal potential” to develop in June and persist through much of the summer season.

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Contact Randy Mann at [email protected].