How Dry is California Going to Be in the Next Year or Two?

The latest U.S. winter outlook spells trouble for dry California.

The Los Angeles Times

The latest U.S. winter outlook spells trouble for dry California.

From the National Oceanic and Atmospheric Administration (NOAA), I’ve included this excerpt from a recent article:

It’s important to know when the drought is active in California, and when it is not. A good rule of thumb for when to expect rain is to look for the monthly rainfall in the 40th percentile of the five-year normal (a figure that varies from month to month but that you can calculate by combining the mean and standard deviation of the monthly rainfall). If it’s not 40th percentile, then the drought has passed and the rain is on its way.

During the month of May, for example, the 40th percentile of the normal is 40.6 percent. So you know that May will bring the start of the next wet, rainy season. During April, the normal 40th percentile is 39.5 percent. So April is a bad month to look for rain, because it’s the end of the wet season.

In the following month, June, the dry season runs into the end of the season, and we have the dry period of August. There are lots of models that have been put forward, and they all have different assumptions and different models, but I’ll call this a 50-50 shot.

This is the first year that we have a 50-50 shot, and it is hard to go backward with the models. We know that for three years, the wet season ended in September, even though we had some rain in May, June, and July. The trend line on the average of the five-year averages of the last five years is going over toward the June to September range.

Now the question is, how dry is California going to be in the next year or two? If we’re going to be less than 40 percent moisture, then we’re going to get a lot of rain, and this time it’s going to be on an even larger scale than in 2015. And even with a greater chance of rain during this next winter, it will be quite dry.

That’s the forecast for how California will look for the next year or two. There

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