Drought, dry, Pacific Decadal Oscillation | The Old Farmer's Almanac

The Stubborn Drought. Any Good News?

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Once again, more than 50% of the contiguous US, where most people live, is in drought. Sigh! This is the third year in a row that the nation has been dry, dry, dry!

Click here to enlarge. Source: droughtmonitor.unl.edu

We are better than we were at the start of the year, when more than 61% of the “lower 48” was in drought. But the hopeful days of early summer, when there was more rain, particularly in the Midwest, have withered. Currently 60% of the nation as a whole and 62% of the contiguous, US are dry and 50.04% of that is in drought. As the US Drought Monitor shows—most of that dry weather is concentrated in the West and Texas.

There is a reason for this long-lasting dry spell. The Pacific Ocean has changed and the prevailing westerly winds are bringing less moisture inland. Scientists have identified a long-term pattern that they call the Pacific Decadal Oscillation (PDO) that shifts warm water to the East or West Pacific. Starting in 1999, we began to have colder waters off the West Coast. This cooled the air and cold air holds less moisture. Less moist ocean air is inland to rain and snow on the American West. We are returning to weather like the 1950s.

The last time we had the Pacific as it is now, there was one long dry spell from 1951–56. Afterwards, there were occasional dry years, but not a long drought. People grew more careful with water resources. The drier weather did not keep the US from feeding the world or enjoying the prosperity of the 1960s.

Meanwhile, the current drought is growing less severe. There has been more rain this summer, just not enough to break the drought. Most of the Southwest has received normal rain and the Central Plains have had abundant rainfall. The size of the drought has grown, but it is less intense. The Short-Term Drought map shows there has been more rain or (where it is white) normal rain—just not enough to refill the reservoirs. People still need to be careful about water.

Meanwhile, there is some hope. About a third of the different scientific weather offices are predicting a warm, wet El Niño for spring. Let’s hope they are right.