Southern parts of US may see intensifying drought in winter as NOAA forecasts cooler north, warmer south
An ongoing and widespread drought is currently in place across the western half of the continental US as a result of the weak Southwest summer monsoon season and near-record-high temperatures. Scientists from the National Oceanic and Atmospheric Administration (NOAA) are now forecasting that southern parts of the US may experience “expanded and intensifying drought” during the winter months ahead.
The agency’s winter outlook for the US predicts warmer, drier conditions across the southern tier of the country, and cooler, wetter conditions in the North, thanks in part to an ongoing La Niña. According to experts, La Niña is a complex weather pattern resulting from variations in ocean temperatures in the equatorial Pacific. La Niña episodes represent periods of below-average sea surface temperatures across the east-central equatorial Pacific. During a La Niña year, winter temperatures are warmer than normal in the Southeast and cooler than normal in the Northwest.
Forecasters at NOAA’s Climate Prediction Center — a division of the National Weather Service — are closely monitoring persistent drought during the winter months ahead, with more than 45% of the continental US now experiencing drought. Their analysis suggests that drought is also present in parts of the Northeast, Ohio Valley, Hawaii and Alaska. Further, the ongoing La Niña is expected to expand and intensify drought across the southern and central Plains, eastern Gulf Coast, and in California during the months ahead. Drought conditions are expected to improve in the northern Rockies, Northwest, New England, Alaska and Hawaii over the coming months.
“With La Niña well established and expected to persist through the upcoming 2020 winter season, we anticipate the typical, cooler, wetter North, and warmer, drier South, as the most likely outcome of winter weather that the US will experience this year,” explains Mike Halpert, deputy director of the Climate Prediction Center.
The greatest chances for warmer-than-normal conditions extend across the southern tier of the US, from the Southwest, across the Gulf states, and into the Southeast. More modest chances for warmer temperatures are forecast in the southern parts of the west coast, and from the Mid-Atlantic into the Northeast. Above-average temperatures are also favored for Hawaii and western and northern Alaska. “Above-average temperatures are favored in the southern two-thirds of the nation, the northeast, portions of Alaska and Hawaii. Below-normal temperatures are favored in southern Alaska and from the northern Pacific Northwest into the Northern Plains, with equal chances for below-, near- or above-average temperatures in the remaining regions,” reveals the analysis.
As far as precipitation is concerned, the NOAA predicts that wetter-than-average conditions are most likely across the northern tier of the US, extending from the Pacific Northwest, across the Northern Plains, Great Lakes and into the Ohio Valley, as well as Hawaii and northern Alaska. The greatest chances for drier-than-average conditions are predicted in the Southwest, across Texas along the Gulf Coast, and in Florida. More “modest chances” for drier conditions are forecast in southern Alaska, and from California across the Rockies, Central Plains and into the Southeast. The remainder of the US, including the Mid-Atlantic and Northeast, falls into the category of equal chances for below-average, near-average or above-average precipitation.
Meanwhile, due to the unprecedented heat globally, September 2020 has turned out to be Earth’s hottest September since 1880, according to NOAA’s National Centers for Environmental Information, which adds that 2020 could rank among the three warmest years on record for the globe. The average global temperature in September was 1.75 degrees Fahrenheit — above the 20th-century average of 59.0 degrees Fahrenheit. This surpasses the average global temperatures for both September 2015 and 2016 by 0.04 of a degree Fahrenheit, which previously tied for the hottest Septembers on record.
“The month's warmth also contributed to 2020’s trend as a remarkably hot year, with the year-to-date global temperatures running second highest in the 141-year climate record. The 10-warmest Septembers have all occurred since 2005, with the seven-warmest Septembers occurring in the last seven years,” say scientists.