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14 FOUR SEASONS BREEZE | JANUARY 2016 By Len Tavernetti El Niño is a farmer. It farms the moisture from the ocean, packages it in clouds and ships it across the ocean. For shipping it relies on Atmospheric Rivers (AR). ARs can be thousands of miles long but are relatively narrow (200-300 miles wide) and carry tremendous amounts of vapor -- more water than the Amazon River. They travel about one mile above the ocean and on reaching land are forced upward to begin releasing their cargo. ARs traditionally travel north along the western Pacific up to Alaska. Here the winds of semi-permanent high pressure whips them around clockwise sending them southeast toward the North American heartland. As El Niño pushes these clouds of vapor north, more and more precipitation is delivered. A strong El Niño, like the current one, will produce record amounts of rain and snow. The Alaskan high periodically oscillates to the west around the winter solstice. As it does, it squeezes the AR and restricts flow (like construction on HWY 91). Since the El Niño is still pushing water vapor north, an outlet detour develops near Hawaii to relieve the pressure. Because of its proximity to Hawaii, the detour is called the Pineapple Express. With the high gone, a low pressure cell forms off the coast of British Colombia and its winds circulating counter clockwise draw the AR detour toward our northwestern states. This traditional El Niño condition saturates northern California with record amounts of rainfall. In December and January of 1861-2 it rained for 43 straight days. The next atmospheric development is very important to southern California. The low can weaken, allowing some of the vapor traffic to stay south. This re-direction sends the AR toward central or sometimes southern California. So, if all three conditions occur, an El Niño forms (which it has this year), the Alaskan high oscillates and a weak low develops off the California coast, Beaumont could receive a large amount of rain this winter. What is it like being the bullseye of the Pineapple Express? In January 1993 Beaumont received 18 inches in a fortnight. The Redlands Daily Facts newspaper covered the story for its city, our nearby western neighbor. Their daily rainfall chart accounts for nearly 12 inches of rain. On Jan. 5 the residents were looking forward to a rainy winter following several years of drought. By the 10th they were worried. Alabama Street was flooded and closed. Daily accidents on I-10 were common. By the 16th San Timoteo Creek had undercut the railroad bridge at Live Oak Canyon and the Alabama Street bridge over the Santa Ana River had collapsed. The major problem for residents seemed to be the psychological depression of 14 uninterrupted days of rain. The Pineapple Express was finally ended by a cold front with freezing temperatures, which brought clear skies and sunshine relieving the depression. Unlike a hurricane that delivers a large amount of water all at once, the Pineapple Express spreads a large amount of water over several days and these manageable bites minimize damage. Redlands daily rainfall in Jan. 1993 Day Rain 6 1.30 7 2.50 8 0.84 9 0.16 10 0.29 11 0.29 12 0.48 13 0.90 14 0.87 15 0.90 16 2.20 17 0.69 18 0.92 19 0.14 20 0.00 The Pineapple Express The Pineapple Express heading toward California

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