Dry conditions in the West that have dashed hopes of a respite from the brutal drought are expected to persist across the region into spring and beyond, forecasters said Thursday.
Dan Collins, a meteorologist with the National Oceanic and Atmospheric Administration, said in a briefing that a continuation of La Niña, a climate pattern that originates in the Pacific Ocean and affects weather worldwide, will contribute to what is expected to exceed normal temperatures, and less than normal precipitation, over much of the west through May.
dr. Collins said he didn’t expect much improvement after that month either, especially in California, which suffered extremely dry conditions last summer that led to water shortages and contributed to several massive wildfires.
“From a climate perspective, there doesn’t appear to be a major change in drier-than-normal conditions in the coming months,” he said.
Most of the western half of the country remains in drought, although wet weather in the second half of last year reduced the severity of conditions in many areas. The forecast for more heat and drought means that the drought will continue over most of the west.
For much of the Southwest, that very likely means a prolonged severe drought, or megadrought, which started in 2000, will continue for a 23rd year. Scientists studying the region’s past climate said in a study published this week that the current megadrought is now the driest two-decade period in at least 1,200 years. Their simulations also predicted that it would continue this year and likely longer.
dr. Collins said droughts could also develop in some areas, particularly south-central Arizona and eastern and coastal Texas. The situation could improve in much of eastern Washington state.
During La Niña, colder-than-normal sea surface temperatures in the equatorial Pacific affect the amount of energy put into the atmosphere, which in turn affects the jet stream, the flow of fast-moving air high in the atmosphere. In the United States, La Niña usually, but not always, results in warmer conditions in the southern part of the country.
dr. Collins said La Niña was expected to last through May and sea surface temperatures in summer are likely to shift to neutral conditions, neither warmer nor colder, reducing the atmospheric effect.
The next three months are also forecast to be warmer than usual in most of the eastern half of the country. Wetter-than-normal conditions are forecast for the Ohio Valley and droughts are likely to develop in Florida.
Despite the snow storm that hit much of the northeast at the end of January, the month was drier than average across the region.
The blizzard was what meteorologists call a bomb cyclone, which occurs when a mass of cold air collides with a warmer one, leading to a very rapid drop in air pressure, high winds and, especially if it happens along the coast, heavy snowfall.
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Samantha Borisoff, a climatologist with the Northeast Regional Climate Center at Cornell University, said it happened on Jan. 28. The storm formed over warmer-than-normal ocean waters and absorbed more moisture, resulting in snowfalls of 3 feet or more in some places.
Ms. Borisoff said that while it can’t be determined with certainty at this time, global warming may have affected the storm’s strength because as humans pump greenhouse gases into the atmosphere, both the ocean and the atmosphere are getting warmer.
A bomb cyclone depends largely on the temperature difference between the cold and warm air masses for its energy, so an air mass developing over a warmer ocean would create a greater temperature difference with the cold mass developing over land, causing the storm. Coincidentally, Ms Borisoff said, parts of the western North Atlantic have been “pretty warm.”
NOAA data showed January was the sixth warmest globally in the modern record, which is 143 years old. Given La Niña and other factors, forecasters said there was only a 10 percent chance that 2022 would be the warmest year on record. But as in years past, as the world continues to warm, this year is almost certainly in the top 10 warmest.