The Climate Prediction Center has backed off its forecast for a weak or moderate El Nino this winter. The NOAA forecast is now for neutral conditions: the infamous El Nothing.
At this time of the year, it’s understandable as these predictions often change and here’s why.
We’re in the so-called “Spring Predictability Barrier.” In spring, the El Nino Southern Oscillation (ENSO) is often in a transition from one phase to another. For example, an El Nino condition could be decaying and passing through neutral condition to a La Nina phase, or vice-versa. Overall, at this time of the year, El Nino or La Nina events are notoriously difficult to predict.
Of course, another factor is, as you get closer to winter, the models become more accurate because there’s less time for inaccurate oceanographic and atmospheric data to be amplified at model initialization. In this period of the year, you can either shake your fist at the sky in frustration or as astrophysicist Dr. Weymann of Atascadero would say, “Many climate scientists think the most reliable strategy is ‘WAS’ (wait and see).”
As the temperatures and currents of the Pacific Ocean change, so does our weather. Changing conditions in the Pacific can trigger El Nino and its sister, La Nina, which can actively influence our weather — either wet or dry. Neutral conditions typically don’t produce any reliable seasonal rainfall predictions along the Central Coast.
Since 1950, NOAA has used sea surface temperatures (SST) in a central equatorial region of the Pacific Ocean called Nino 3.4 as the standard for classifying El Nino (warmer-than-normal SST) and La Nina (cooler-than-normal SST) events. The fortune-telling SST cycles in Nino 3.4 are categorized by the amount they deviate from the average SST. In other words, an anomaly.
A weak El Nino is classified as an SST anomaly between 0.5 and 0.9 degrees Celsius; a moderate El Nino is an anomaly of 1.0 to 1.4 degrees Celsius; and a strong El Nino ranges from 1.5 to 1.9 degrees Celsius. A very strong El Nino anomaly is anything above 2.0 degrees Celsius (or 3.6 degrees Fahrenheit). Neutral conditions — El Nothing or El Nada —ranges between plus 0.5 and minus 0.5 degrees Celsius anomaly levels, or the sector between El Nino and La Nina.