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Will there be an El Nino? What does it mean?



Despite my Ph.D. in meteorology and the fact that I successfully predicted both the drought and the most recent lottery number*, I have no idea if this El Nino that seems to be brewing in the Pacific will have the desired impact here in dry, dry California, where we’re currently in the midst of a horrible fire season, and the worst months lie ahead.

We were told last year that El Nino was coming and that it could have a positive impact on the drought. And then we ended up with the third driest winter in California’s history.

No wonder everybody got so excited when predictions of a new El Nino started surfacing some months ago. I’ve been watching the media on this, and the drumbeat is getting louder and louder. Now, the San Francisco Chronicle (which has been covering the drought quite closely) is forecasting that this winter’s El Nino will be “worse than ‘97-‘98” and could in fact be a “monster.”

That is great news, but if you really pay attention to these things you know that El Nino, in and of itself, is a very poor indicator of coming precipitation. Just three days ago, the same Chronicle noted that some of the state’s wettest winters have occurred when no El Niño was present, or during the opposite condition, La Niña, in which the Pacific Ocean is cooler than usual,” and they added this kicker: “Fact is, out of 23 El Niño events over the past 65 years, only nine resulted in wetter-than-average winters.”

Still, NOAA, the National Oceanic and Atmospheric Administration, is bullish. In their most recent update, they predict “a strong [El Nino] event” that will achieve “peak strength” early this coming winter, followed by “a 90% chance that El Nino will continue through [the] Northern Hemisphere winter” and then “last into early Spring 2016.”

What does NOAA think it means for rain? Here’s a map showing the current prediction status for next December, January and February, traditionally California’s rainiest months.


You can see that NOAA is thinking the big rains will be in the far southern part of the state. According to the map, Northern California, from about Mendocino down to San Luis Obispo, might be slightly higher in rain than normal. From SLO down to about L.A. the chance of higher than normal increases, although not by much. It’s not until you get from L.A. south to San Diego and Mexico (where the darker green is) that there’s the greatest chance for significantly higher rainfall.

That’s too bad. The majority of California’s water comes from Northern and Central California’s reservoirs, water tables and Sierra snowpack, so even a ton of rain and snow in the San Gabriels and the deserts will make barely a dent in the drought. Still, one can always hope.

* Actually, none of these claims is true, but it was fun to say them

  1. More rain is predicted for Northern California than Southern California despite the fact that Southern California is predicting ~50% increase in rainfall over average while Northern California is predicting ~33% increase. That puts the additional rainfall in Healdsburg for example at 14 inches additional precipitation (.33*42 inches annual precip) for a total of 56 inches while Los Angeles will only receive 7.5 inches of additional precipitation (15*.5) for a total of 22.5 inches.

    Granted this is all speculation and I don’t trust these forecasts until the rain is on the ground, but it is still important to note that 33% increase up here is a much larger volume of water than a 50% increase in Southern California, though it will be a more statistically significant event in Southern California.

  2. doug wilder says:

    That map looks oddly like Cookie Monster.

  3. Bill Stephenson says:

    All that rain in the spring means little in late summer unless there is adequate storage.

    As a California resident you know this, Steve, but for your non-Cali readers it goes like this. . .

    In the past 35 years California’s population has grown by 100%.
    Farm use of water has increased by 170%
    Mandated fresh water flow to protect aquatic species has increased by an unknown but substantial number.

    Federal and State funded water storage (construction of dams) has increased by 0%.

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