A wet fall and snowy winter in the Northwest United States this year will be the result of one of the most powerful El Niño events on record. Oregon Capital Chronicle reports. Climatologists cannot make an accurate forecast, because against the backdrop of global warming, the behavior of both El Niño and its opposite phase, La Niña, becomes less predictable.
El Niño is a natural climate cycle in which temperatures in the central and eastern equatorial Pacific Ocean become at least 0.9°F (0.5°C) above normal. This occurs due to the weakening of the trade winds, which usually bring cold water to the surface. The phenomenon alternates with the La Niña phase, during which, on the contrary, the waters in the region become cooler than usual, RTVI.US previously reported.
This climate phenomenon influences weather patterns, air temperatures and storm tracks. El Niño and La Niña occur at irregular intervals – usually every 2-7 years.
On June 11, the US National Oceanic and Atmospheric Administration (NOAA) announced the formation of El Niño in the tropical Pacific Ocean and issued an official warning (El Niño Advisory). According to forecasts, the phenomenon may reach a level of moderate to severe intensity by the fall. There is a 63% chance that ocean surface temperatures will be more than 3.6 °F (2.0 °C) above normal. In this case, NOAA classifies the event as a Very Strong El Niño.
“This could be one of the strongest El Niños we've ever seen,” said Oregon climate scientist Larry O'Neill.
A strong El Niño typically creates conditions in the Caribbean and tropical Atlantic that prevent storms from forming. The Gulf Coast and eastern United States may experience extended periods of dry weather.
At the same time, hurricane season tends to become more active in the central and eastern Pacific. In the western US states, many of which are suffering from drought, El Niño could bring long-awaited rain. Due to record heat in the west of the country, very little snow fell in the first months of this year, which is why a “reservoir” of water from the snow cover did not form. NOAA estimates that there is a 50% to 70% chance of temperatures remaining above normal between July and September.
If El Niño is weaker than expected, the drought could continue. In the event of the formation of a powerful phenomenon, the water level in reservoirs will increase and snow reserves will be restored.
O'Neill emphasized that El Niño's influence on weather patterns does not always correspond to climate models.
“In recent years, La Niña has behaved completely differently than before. For example, last year we had a weak La Niña, which usually provides good snowpack, but we ended up with the worst snow season on record. Therefore, it is quite difficult to predict exactly how El Niño will develop,” O’Neill added.
