Is a new megadrought brewing in the West?

The far West is in the middle of a very dry summer season. Here in North Idaho, the total precipitation for July and August was 0.69 inches, well below the normal of 2.15 inches for both months. From July 7 through Sept. 6, a puny 0.12 inches of moisture was recorded.

As of Saturday, we’d had 20 days with high temperatures at or above 90 degrees. Our hottest afternoon occurred on Aug. 17 with a reading of 100 degrees. On Saturday, the mercury shot up to 98 degrees. At Spokane International Airport, there were two days with highs over the 100-degree mark. They occurred on Aug. 16 as the mercury hit 101 degrees and the following day, the 17th, when the high was 100 degrees.

August was also a torrid month for much of the western U.S. In Phoenix, there were 50 days in 2020 with high temperatures at or above 110 degrees, a record. The old record occurred in 2011 when Phoenix reported 33 days with temperatures at or above 110 degrees.

In Sacramento, where I used to live and many of my friends and relatives still reside, August of 2020 was the hottest month ever recorded. During the middle of last month, there were eight days in a row with highs in the 100s. Aug. 16 was one of the hottest days as highs in many locations across California’s Central Valley were above 110 degrees.

With the long and hot summer season, drought conditions have spread to more than a third of the U.S., especially in the far West. The latest data shows moderate to extreme drought conditions in the southwestern U.S. extended into Texas. Very dry regions have also increased in parts of the northern Great Plains eastward through Iowa, Illinois and into the Northeast.

The extremely dry weather has also led to another disastrous year for wildfires in California. Record-breaking blazes scorched about 1 million acres in August. Unfortunately, more hot weather is expected for at least another week with no rain in sight for the Golden State.

According to a new study from Columbia University and published in Science Advances, the western U.S. has experienced one of its driest 20-year periods in approximately 1,000 years. Despite a few wet years, the southwestern regions may be in the midst of another “megadrought” which, according to tree ring data, can last for decades. Since 800 A.D., evidence shows that there have been four previous megadroughts. They occurred in the late 800s, the mid-1100s, the 1200s and the late 1500s.

Researchers compared soil moisture records calculated since 2000 and concluded that the current drought is “already outdoing the three earliest ones.” The worst megadrought in the West likely occurred from 1575 to 1603. The article also states that the ancient droughts went on at least for several decades, but the one in the 1200s lasted for nearly a century.

According to the data, the 20th century was the wettest when compared to the last 1,200 years. It’s very possible that the western U.S., especially the Southwest, will be seeing more dry weather in the 2020s. Scientists blame the current western drought on natural cycles and climate change.

As I mentioned last week, since 2014, May and June’s combined precipitation in Coeur d’Alene was above normal. The following July and August had moisture totals below normal, which was the case again in 2020.

In terms of our local weather, more hot weather is expected once again toward the end of the week as the strong high pressure system intensifies over our region. It’s possible that we’ll have another day with highs around 90 degrees. The latest 90-degree day in recorded history occurred on September 26, 1963, with a record high on that date of 90 degrees.

The long-range computer models are continuing to show very dry conditions across much of the far West, including the Inland Empire through at least the middle of the month. We started this dry pattern on July 7. Typically, a wet or dry weather pattern will last for approximately six weeks. But, there are occasions when we’ll see a back-to-back six-week pattern, which is likely the current scenario. Therefore, the northwestern U.S. may not see any significant moisture until late September or early October, around the end of this current six-week dry cycle.

This long dry spell may also point to an interesting winter season. In this crazy pattern, we often go from one extreme to the other in short order. In other words, we may get another back-to-back six-week pattern of cold and snowy weather during the winter of 2020-21. Many forecasters are predicting a harsh winter for parts of the Northern Hemisphere. Stay tuned.