Saturday, May 18, 2024

Glorious rain here, horrid drought there

| May 24, 2020 1:00 AM

After a drier-than-normal April across the Inland Northwest, the storm door has opened and some much-needed rain has fallen over the past week.

The recent moisture has sent our precipitation total in May well above the normal of 2.37 inches as about 3 1/3 inches of rain has fallen. This wetter-than-normal pattern is expected to continue into early June.

As Cliff and I have been mentioning, conditions across the region should start to turn drier and warmer toward the middle of next month. For the summer of 2020, we do see hotter weather with a few days at or above the 100-degree mark.

Despite the recent moisture across the Pacific Northwest, the winter of 2019-20 has been drier than average across many stations in the Far West.

For example, since Oct. 1, 2019, Portland has received just over 75 percent of its normal precipitation. Northern and central California has also seen less rainfall as Redding is reporting only 61 percent of normal and Sacramento has only had about 54 percent of its average seasonal rainfall.

However, in Southern California, moisture totals are close to average levels for the 2019-20 season. Last year, sea-surface temperatures were a little warmer, which enhanced some Pacific storm systems that moved into that part of the country.

At Cliff’s station, moisture totals are above average as nearly 14 inches of rain and melted snow has been reported since Jan. 1. The normal is around 11.50 inches.

At Spokane International Airport, precipitation since the beginning of the year is over 7.50 inches, which is above the average of around 7.25 inches.

In other areas of the Northwest, Moses Lake, Wash., is about 80 percent of normal for the 2020 season. Lewison is having a good year as it is currently around 25 percent above average.

Last month, a study published in Science says that much of the western U.S. and northern Mexico may be in an extreme long-term drought worse than any in recorded history. The research is based upon modern weather observations and new tree-ring reconstruction data dating back over 1,000 years.

According to an article from Columbia, based on tree-ring data dating back to 800 A.D., there were four major megadroughts in the western U.S. These occurred in the late 800s, mid-1100s, the 1200s, and the late 1500s.

All of the “ancient megadroughts” were longer than 19 years and the one in the 1200s lasted for nearly a century. There were other studies that said that within the last 1,200 years, scientists claim that there were two long dry spells in parts of California, each lasting for nearly 200 years.

The recent study primarily covers an area across nine states, including Oregon, California, Nevada, Utah, Arizona, Wyoming, much of New Mexico, the western half of Colorado, the extreme southwestern portion of Montana, extreme western Texas, central and southern Idaho.

Since 2000, much of this region has been suffering through a long string of dry years. Scientists from this study say that data from 2000 to 2018 shows that the current drought is worse than the three earliest megadroughts. The worst megadrought was from 1575 to 1603 and this particular one of the 21st century may soon rival the fourth big period of dryness. Also, this current drought “is affecting wider areas more consistently than any of the earlier ones.”

Scientists say Earth’s rising temperature and other climate change factors are the likely cause of this current drought pattern in the Far West. Some also say that these western droughts are projected to be longer and more severe down the meteorological roadway. Although last year was wetter than normal across much of the Far West, the drier than normal weather pattern did return for this season.

From the late 1970s to the mid 1990s, much of the western U.S. was enjoying a period of generally wetter-than-normal weather. With a much bigger population and agriculture, the demand for water is higher than ever. Water tables are already much lower than in previous years and if a new cycle of a long period of dryness is indeed moving in, then much of the West, especially California, may be in for some very challenging times for water later this century.

We’re already seeing the effects of the dry conditions since 2000 as many reservoirs have been dramatically lowered in the southwestern U.S. In 2017 and 2018, there were record wildfires in the Far West, especially in California.

However, here in North Idaho, we’ve been having a period of near- to above-normal moisture over the last 15 years. And, it looks like 2020 will be another year with good precipitation totals despite the forecast of the drier-than-average summer season.

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Contact Randy Mann at