Atmospheric rivers are a plume of moisture that extend across the Pacific to near Hawaii. When they hit land they can cause heavy rains and snow. Here’s a look at the phenomenon:
Atmospheric rivers are long and relatively narrow bands of water vapor that form over an ocean and flow through the sky, transporting much of the moisture from the tropics to northern latitudes.
They occur globally but are especially significant on the West Coast of the United States, where they create 30% to 50% of annual precipitation and are vital to water supplies but also can cause storms that produce flooding and mudslides, according to the National Oceanic and Atmospheric Administration.
Formed by winds associated with cyclones, atmospheric rivers typically range from 250 miles to 375 miles (400 to 600 kilometers) in width and move under the influence of other weather.
Many atmospheric river events are weak. But the powerful ones can transport extraordinary amounts of moisture. Studies have shown that they can carry seven to 15 times the average amount of water discharged daily by the Mississippi River, according to the U.S. Geological Survey.
When the moisture-laden air moves over mountain ranges such as the Sierra Nevada along the California-Nevada line, the water vapor rises and cools, becoming heavy precipitation that falls as rain or snow, according to NOAA.
While traditional cold winter storms out of the north Pacific build the Sierra snowpack, atmospheric rivers tend to be warm. Snow may still fall at the highest elevations but rain usually falls on the snowpack at lower elevations. That can quickly prompt melting, runoff and flooding and decrease the snowpack needed for California’s water supply.
It is a nickname for a strong atmospheric river in the tropical Pacific near Hawaii.
The name came from research published in the 1990s by scientists Yong Zhu and Reginald E. Newell of the Massachusetts Institute of Technology. Atmospheric rivers are often referred to as ARs.
Workers shield themselves from the rain at the Griffith Park Observatory Thursday, Feb. 13, 2025, in Los Angeles. (AP Photo/Damian Dovarganes)
FILE - Residents evacuate past damaged vehicles after storms caused a mudslide, Monday, Feb. 5, 2024, in the Beverly Crest area of Los Angeles. (AP Photo/Marcio Jose Sanchez, File)
RABAT, Morocco (AP) — Tanzania and Tunisia secured the last two available spots in the Africa Cup of Nations last 16 on Tuesday, thanks to their 1-1 draw in Group C.
It wrecked Angola's hopes of squeezing through as one of the best third-place finishers with just two points from Group B. Angola’s goal difference was better than that of Comoros, the third-place finisher in Group A.
Feisal Salum’s equalizer for Tanzania sent the Taifa Stars through. While Tanzania and Angola both finished with two points and a goal difference of minus 1, the goal scored by Salum, who is commonly known as Fei Toto, took Tanzania's tally to three — one better than Angola's two goals.
All the other group stage survivors were decided already on Monday because of Angola and Comoros’ relatively low points total. It meant teams that already had more than two points and were already assured of at least third place in their groups could be certain of reaching the last 16.
The four best third-place teams from the six groups progress, along with the top two in each. Head-to-head results are the first determining factor if two teams finish with the same amount of points in a group.
Here's a look at which teams went through from the six groups:
Host nation Morocco progressed as the winner of Group A, followed by second-place Mali with just three points from three draws. Morocco next faces a third-place finisher from Groups C, D or E on Sunday. More importantly for the Atlas Lions, they will continue their run to the final in the almost 70,000-capacity Prince Moulay Abdellah Stadium, which will also stage the final on Jan. 18. Mali awaits Tunisia for a showdown in Casablanca on Saturday.
Seven-time champion Egypt won Group B to advance with South Africa in second, ahead of Angola. Egypt stays in Agadir and next faces a third-place finisher from Groups A, C or D on Jan. 5. South Africa faces a likely tough game against the runner-up in Group F on Sunday.
Nigeria was already sure of topping Group C before its 3-1 win over Uganda on Tuesday. The Super Eagles will remain in Fez for their first knockout game against a third-place finisher from Groups A, B or F on Jan. 5. Tunisia faces Mali in the last 16, and Tanzania progressed as the fourth-best third-place finisher.
In Group D, which had its final games later Tuesday, 2021 winner Senegal, Congo and Benin were all sure of progressing as they all had three points or more, and were already certain to finish above Botswana, which lost to Senegal and Benin before its final game against Congo. Even if Botswana beat Congo, it could not finish above Benin because of their head-to-head record.
Algeria is certain to win Group E before its final group games, and Burkina Faso and Sudan are certain to advance because they cannot finish below Equatorial Guinea, which lost both games against them. Algeria will play the second-place finisher from Group D on Jan 6. in the same Rabat stadium where it has played all its games so far.
Defending champion Ivory Coast, five-time winner Cameroon, and Mozambique are assured of progress from Group F. Gabon, sure to finish last, was already eliminated before the last round of group games on Wednesday, when the order of the top three teams will be decided. Ivory Coast plays Gabon and Cameroon faces Mozambique.
AP at the Africa Cup: https://apnews.com/hub/africa-cup-of-nations
Morocco fans wait for the start of the Africa Cup of Nations group A soccer match between Zambia and Morocco in Rabat, Morocco, Monday, Dec. 29, 2025. (AP Photo/Themba Hadebe)
Tunisia's supporters wait for the start of the Africa Cup of Nations group C soccer match between Tanzania and Tunisia in Rabat, Morocco, Tuesday, Dec. 30, 2025. (AP Photo/Mosa'ab Elshamy)
A Moroccan fan waits for the start of the Africa Cup of Nations group A soccer match between Zambia and Morocco in Rabat, Morocco, Monday, Dec. 29, 2025. (AP Photo/Themba Hadebe)
A Moroccan fan waits for the start of the Africa Cup of Nations group A soccer match between Zambia and Morocco in Rabat, Morocco, Monday, Dec. 29, 2025. (AP Photo/Themba Hadebe)
Senegal fans support their national team during the Africa Cup of Nations group D soccer match between Senegal and DR Congo in Tangier, Morocco, Saturday, Dec. 27, 2025. (AP Photo/Themba Hadebe)
