“The question is: What makes the Northern Hemisphere warmer? And we’ve found that it’s the ocean circulation.”įrierson and his co-authors first used detailed measurements from NASA’s Clouds and Earth’s Radiant Energy System, or CERES, satellites to show that sunlight actually provides more heat to the Southern Hemisphere – and so, by atmospheric radiation alone, the Southern Hemisphere should be the soggier one.Īfter using other observations to calculate the ocean heat transport, the authors next used computer models to show the key role of the huge conveyor-belt current that sinks near Greenland, travels along the ocean bottom to Antarctica, and then rises and flows north along the surface. “It rains more in the Northern Hemisphere because it’s warmer,” said corresponding author Dargan Frierson, a UW associate professor of atmospheric sciences. In general, hotter places are wetter because hot air rises and moisture precipitates out. 20 in Nature Geoscience, explain a fundamental feature of the planet’s climate, and show that icy waters affect seasonal rains that are crucial for growing crops in such places as Africa’s Sahel region and southern India. But a new University of Washington study shows that the pattern arises from ocean currents originating from the poles, thousands of miles away. Scientists long believed that this was a quirk of the Earth’s geometry – that the ocean basins tilting diagonally while the planet spins pushed tropical rain bands north of the equator. The Palmyra Atoll, at 6 degrees north, gets 175 inches of rain a year, while an equal distance on the opposite side of the equator gets only 45 inches. Near-average amounts of rain and/or snow are forecast along much of the West, East and Gulf coasts, as well as across the northern tier.A quick glance at a world precipitation map shows that most tropical rain falls in the Northern Hemisphere. Portions of the mid-Atlantic coastline might see a wetter-than-average fall, but the drought is most concentrated over the central and western U.S., where conditions are expected to be dry. The most favored areas for below-average precipitation include parts of the lower Ohio and mid-Mississippi valleys and the central Rockies.įIRST GLIMPSE OF FALL FOLIAGE PREDICTIONS FOR THE 2022 SEASON NOAA's precipitation outlook for the next three months doesn't look very promising to help alleviate it.ĭrier-than-average conditions are predicted across much of the country, from the Rockies to the Appalachians, which means rain and/or snow will likely be hard to come by between September and November.

was experiencing drought conditions as of Thursday, according to the latest U.S. NOAA's precipitation outlook for meteorological fall (September through November).Ībout 49% of the U.S. An upper-level area of high pressure or a cold front can provide a period of warmer or cooler weather, respectively, that bucks the overall three-month trend. It's important to note that this is an outlook for a three-month period. No areas are expected to be cooler than average this fall, but near-average temperatures are forecast along the northern tier from Washington state into the northern Rockies and northern Plains. WHY FALL SHOULD ACTUALLY BEGIN ON SEPTEMBER 1 While not as far above average, temperatures are still predicted to be warmer than average in most of the rest of the Lower 48. Well-above-average temperatures are also expected across much of the Northeast and coastal mid-Atlantic, as well as from the central and southern Rockies into West Texas. The warmest temperatures relative to average are forecast to be in Utah, Colorado and parts of eastern and southeastern New England. NOAA's temperature outlook for meteorological fall (September through November).Īccording to NOAA, above-average temperatures are predicted for a majority of the nation this fall.

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