The severe drought that hit much of the western half of the United States in the spring and summer is likely to last at least into late autumn, state forecasters said Thursday.
The September through November outlook compiled by meteorologists for the National Oceanic and Atmospheric Administration suggests that above-average temperatures are likely across most of the west, with the exception of Washington and parts of Idaho, Montana, and North Dakota.
Rainfall is expected to be below normal from the southwest to the Rockies and Northern Plains.
Taken together, this means bad news for a part of the country that is already experiencing significant drought effects, including dwindling water supplies, stunted crops, barren pastures and exploding forest fires.
“We expect a prolonged drought in much of the western United States,” said Matthew Rosencrans, a NOAA meteorologist, during a conference call with reporters.
According to the United States Drought Monitor, 47 percent of the land area of the contiguous 48 states is currently affected by varying degrees of drought, almost all of them in the High Plains or from the Rocky Mountains to the west. Drought affects nine states, including California, Nevada, Arizona, Utah, Oregon, and North and South Dakota.
Last month the drought in Arizona and New Mexico subsided. So-called monsoon rains helped, said Mr Rosencrans. These occur in summer when atmospheric conditions draw Pacific moisture into the region.
But elsewhere in the west, dry and hot conditions lasted until July, NOAA said. California, Nevada, Oregon and Washington saw their hottest July in 127 years, while five other states, including Utah and Colorado, were on the verge of breaking records.
The drought situation is particularly dire in California, where 49 percent of the state falls into the worst drought category. Farmers in the state’s Central Valley have slashed their water allocations, wells are drying up in some cities, and several large forest fires are raging now, including the Dixie Fire, now the largest single fire in California history.
About half of Utah, a third of Nevada, and a quarter of Oregon are also in the heaviest category.
In the next three months, the drought could develop in northeast Colorado and western Nebraska, Rosencrans said. The only improvement could be in the western parts of Oregon and Washington.
As for the outlook beyond November, Mr Rosencrans said the likelihood of La Niña developing in the fall and lasting through the winter is better than 50 percent.
In La Niña, sea surface temperatures in the equatorial Pacific Ocean drop below normal, causing changes in atmospheric circulation that can affect weather around the world. In the United States, this often, but not always, means warmer and drier conditions in southern California, the southwest and southeast, and colder and wetter conditions in much of the northern part of the country.
Overall, according to NOAA, the 48 contiguous states experienced the 13th warmest July ever. To compensate for the westerly heat, temperatures below average were recorded in the central plains, parts of the Midwest and Southeast, and northern New England.