What is the El Niño? What is its current status?

Q: What is the El Niño? What is its current status?

A: The El Niño is warming of the tropical Pacific Ocean. A major El Niño event occurs every 3 to 7 years and is associated with changes in the weather patterns worldwide. Signs of an El Niño are rise in surface pressure over the Indian Ocean, Indonesia, and Australia, lower air pressure over Tahiti and the rest of the central and eastern Pacific Ocean, weak trade winds in the south Pacific, and warm water spreads from the west Pacific and the Indian Ocean to the east Pacific. This causes drought in many areas of the western Pacific and flooding in many areas of the eastern Pacific. El Niño episode is defined as an anomaly of 0.5 C in the tropical Pacific for more than 5 months. We are currently in a weak El Niño as the Niño 1+2, 3.2, 4 regions are all warming less than 1 C. Warming over 1 C in any of those three regions is defined as a moderate El Niño. The El Niño typically affects the DC area by enhancing the subtropical jet(STJ) and thus bringing above normal precipitation during the winter and fall. Temperatures usually are near average in a Niño year. The STJ helps the DC area receive more chances for snowfall due to enhanced moisture from the Gulf of Mexico and favorable coastal low development. Most of our major winter storms are due to an active STJ as it supplies the moisture and can lead to bigger storms to form rather than the Polar Jet.