The El Niño weather pattern has arrived on the West Coast, and it is a welcome sight for those in agriculture who have been dealing with historic drought conditions for several years.

On Tuesday, Jan. 5, the forecasting division of the National Weather Service predicted that as many as 15 inches of rain could drench California over the following 16 days. While that was an upper-end prediction for the rainiest of sites, it was good news nonetheless.

Mike Anderson, state climatologist for the California Department of Water Resources, said the series of storms lined up in the Pacific Ocean and expected to hit the state over the next two weeks are what one would expect to see as a result of the El Niño conditions.

Those conditions are typically described as warmer-than-usual Equatorial Pacific waters, which tend to create atmospheric conditions that allow for greater rainfall in California. Anderson said the “flattening out” of the high pressure system off the coast of California is occurring, which enables these Pacific storms to head directly into the state rather than take a northern detour as they have the past four years.

He noted that El Niño conditions in the past have led to intense precipitation in the January-through-March time frame with rains lingering into May.

“That’s would be very helpful,” he said, noting that over the last few years California has had very little rain beyond March.

Although there has been above-normal rainfall in the state since this water year began Oct. 1, Anderson said reservoirs are still at historically low levels and a great deal of precipitation is needed to make up for previous losses. In past years, it has taken precipitation levels above 150 percent to fill those reservoirs.

While Anderson is optimistic that above-average rain in California will prevail over the next several months, he cautioned that past history upon which climatologists are basing their forecasts is limited. He said there have only been a handful of El Niño years over the past few decades and only two years that come close to duplicating the current conditions that are in effect.

In fact, no year has had as large an increase in ocean temperatures (7 degrees over average) or as large an area of ocean affected (2.4 million miles).

In addition, Anderson said ongoing climate change has created atmospheric conditions that are quite different than the two previous strongest El Niño years (1982-83 and 1997-98).

With all of the caveats stated, however, he does say it is wise to be prepared for a lot of rain this year and all that it will bring. Municipalities throughout the state are making preparations by clearing storm drains, warning residents to do the same and offering sand bags so homeowners can direct the water where they want it to go.

For California growers of annual crops, he said it would be a good idea to assume that the harvesting and planting days they will have over the next several months will be diminished, and there will almost certainly be fewer days that crews can get into the fields.

The El Niño conditions, of course, affect more than just California. In past years, it has meant wetter weather in the southern half of the United States leading to flooding, while the northern half of the country is drier and warmer. Central America stretching to northern countries in South America has experienced dry conditions, while the lower half of South America is typically wetter than usual.

In the agricultural market, which is decidedly global, there will be many effects on growing districts all over the world. However, it is very difficult to generalize and predict outcomes.

While many more storms are expected to hit California, for example, Anderson said each storm will have its own characteristics, with no reliable predictive model until a few days before it forms.

In fact, he noted that while the National Weather Service does forecast 16 days in advance, it is only about a week out in which those forecasts are fairly accurate. There is still a lot of guesswork involved in a two-week forecast, not to mention anything longer than that.