It is because in 2000, the Western U.S. It came at the beginning of what scientists call the megadrought - the second worst in 1,200 years - created by a combination of dry natural cycles and man-made climate change.
Twenty years ago, the worst drought ever occurred in 2003 and 2013 - but what is happening now seems to be the beginning of something very serious. And as we enter the dry summer season, the stage is set for an increase in extreme dry conditions, extensive water restrictions and another dangerous fire season to come.
The picture above is a time of drought in western countries from 2000 to 2021. This latest spike for 2020-2021 (right) is as impressive as any other, but with one significant difference - in this case, the area of the "different drought" is much larger than any other speaker, covered by more than 20%. As we enter the dry season, there is very little chance of improvement - in fact it may only be dry.
With this in mind, there is no doubt that drought in the West, especially in the Southwest, this summer and autumn will be the strongest in recent memory. The only real question is: Will it last as long as the last extended period of drought from 2012 to 2017? Only time will tell.
Currently, U.Somiso Monitor puts 60% of Western provinces under severe, extreme or different drought. The cause of the great drought is doubled; long-term drought exacerbated by man-made climate change and, in a short time, a La Niña event in which the cooler waters of Equatorial Pacific failed to absorb excess moisture.
As a result, last winter's rainy season was quite wet. In fact, it only adds to the damage, when only 25 to 50% of normal rainfall crosses southwest California and California. This was followed by one of the driest and hottest summers in modern times, with two waves of heat history, a cycle of summer rains that has not been seen even in the worst fires of modern times.
The diagram below shows the so-called precipitation precipitation from October to March, compared to the previous six months and the equivalent of six months each year for the past 50 years.
The light brown shading indicates areas where the last six-month extension was 10% dryer over the past 50 years. The dark brown shade indicates areas that have received their lowest rainfall on record during the last six months. Almost all areas are covered with one of those two shades.
Kelsey Satalino, Digital Communications Coordinator from NOAA's National Integrated Drought Information System, says that over the past few months, many provinces including Nevada, Arizona, New Mexico and Utah have experienced a drought since the drought began in 2000. As a result, soil moisture is at its lowest level for at least 120 years.
The Pacific Northwest, however, is very different this season. The northern part of the West has experienced regular snowfall even higher this winter, in line with expectations during a typical La Niña event featuring another jet stream storm track. That fortune did not extend south, however, most areas now have only 50 to 75% of normal snow.
Since the West depends on the melting of snow to fill lakes, dams and rivers, such as Colorado, water availability will be limited this summer. The Colorado River and its tributaries supply water to about 40 million people and five million acres [5 million ha] of farmland. The amount of water flowing into Lake Powell, at the heart of the Arizona-Utah state, in the coming months is expected to be about 45% of normal capacity. Lake Meade, in the Arizona-Nevada state line, has only 40% power.