“How beautiful the rain!
After the dust and the heat….
Across the windowpane
It pours and pours;
And swift and ride, with muddy tide,
Like a river down the gutter roars…
The rain, the welcome rain!”
~ Henry Wadsworth Longfellow
Summer is only days old but already we have grown weary of the heat. Water restrictions and dead landscaping only add to this weariness. So the above quotation could be a not-too-funny joke, an optimistic vision of a wet fall and winter or a writer’s heat-induced delirium. No matter, the very mention of rain is refreshing.
Big weather news! A strong El Niño is expected this fall continuing into winter. For many of us, a simple explanation for a very complex event is in order. Our bag of “El Niño trivia” may include heavy rainfall in Southern California, warm ocean water temperatures off the coat of Chile and the “jet stream.” Those are all correct. Their intricate interaction and causation are scientifically rich. Here is my very concise El Niño interpretation.
To begin, a shift in direction of the trade winds occur. The usual east-to-west pattern reverses to a west-to-east one. Warm tropical waters flow toward South America. Ocean temperatures rise. An area of low pressure forms as warm, moist air rises. Resulting low pressure and atmospheric instability have far-reaching impacts with the primary one being the Arctic jet stream trajectory takes an abnormal dip farther south. In conveyor belt style, storms arrive one after another into Southern California. Rain!
NOAA’s Climate Prediction Center on June 22: Water temperatures in the eastern Pacific Ocean are two-to-three degrees above normal. There is a greater than 85%-90% chance El Niño will continue into 2015-16 fall and winter.
Sue Kilpatrick is a
Crescenta Valley resident and
Official Skywarn Spotter for the
National Weather Service. Reach her at firstname.lastname@example.org.