|Examples/ definitions with source references|Level 5 atmospheric river to unleash flooding across drought-stricken California
October 21, 2021 ...
After nearly a year without rain, a series of potent Pacific storms are directed at Northern California this week, potentially bringing as much as a foot of rainfall and up to three feet of snow in the Sierra Nevada.
Supercharged by a classic atmospheric river pattern, the storms could lead to flash floods and dangerous debris flows in a wide swath of the region already devastated by recent wildfires.
With each successive storm, the moisture potential increases, peaking with possibly a rare category 5 atmospheric river event on Sunday. ...
Atmospheric rivers are a narrow band of concentrated moisture in the atmosphere, cruising more than two miles above the ocean; they can transport as vapor, more than 20 times the water that the Mississippi River does, as a liquid.
By the time Monday morning arrives, the parade of storms could drop as much as 8 to 12 inches of rainfall in parts of Northern California and add another 1 to 3 feet of snow to the high Sierra. For an area plagued by drought, a foot of rain is too much, too fast and too soon and will likely lead to run off, flash floods and debris flow in burn scar areas.
Burn scars -- the charred landscape -- left behind after the Dixie Fire, near Mount Lassen and the Caldor Fire, not far from South Lake Tahoe, remain susceptible to flash floods and debris flows.https://edition.cnn.com/2021/10/20/weather/at...Powerful storm hits California amid warnings of ‘potentially historic rain’
‘Atmospheric river’ expected to bring record-breaking rainfall and strong winds and wreaking havoc across the northhttps://www.theguardian.com/us-news/2021/oct/...Bomb Cyclone and ‘Atmospheric River’ Pummel California With Rain and Wind
Much of the Bay Area was under a flash flood watch on Sunday, with the National Weather Service warning of the potential for mudslides across the region. ...
California bore the brunt on Sunday of what meteorologists referred to as a “bomb cyclone” and an “atmospheric river,” a convergence of storms that brought more than half a foot of rain to parts of the Bay Area, along with high winds, concerns about flash floods and the potential for heavy snow in the Sierra Nevada.
The National Weather Service warned that the rainfall could cause mudslides, especially in areas scorched by wildfires. ...
An atmospheric river is a concentrated plume of moisture that extends over the ocean, typically in the troposphere, the lowest layer of the atmosphere, Mr. Miller said. The current trough was angled toward the North Bay, he said.
In the Pacific Northwest, a bomb cyclone, a type of storm known for its falling atmospheric pressure, was expected to push the atmospheric river south, affecting areas south of San Francisco ...https://www.nytimes.com/2021/10/24/us/bomb-cy...'Too fast, too furious': Bomb cyclone, atmospheric river pound California with heavy rain, flooding ...
A furious storm unleashed from a "bomb cyclone" over the Pacific Ocean slammed ashore Sunday in drought-plagued Northern California, blasting a wide swath of the West Coast with heavy rain, damaging winds, flooding and mudslides.
Over 160,000 homes and businesses in California, more than 170,000 in Washington, and over 28,000 in Oregon were left without power on Sunday due to the extreme weather.
Flooding across the San Francisco Bay Area closed streets in Berkeley and inundated the Bay Bridge toll plaza in Oakland, with some roads under two feet of water in San Rafael. The National Weather Service in Sacramento warned of "potentially historic" rain for the city's downtown.
North of the state capitol in Butte County, California's Highway Patrol closed down State Route 70 due to mudslides and debris flows near the now-contained Caldor Fire, which scorched more than 346 square miles of the Sierra Nevada and burned hundreds of homes. ...
A bomb cyclone forms when air pressure rapidly drops as the storm explosively strengthens. The phenomenon was pulling deep tropical moisture from the Pacific, creating an "atmospheric river," AccuWeather meteorologist Jon Porter said. He described the river as a "firehose of moisture in the sky" capable of unleashing intense rain and mountain snow. https://www.usatoday.com/story/news/nation/20...An atmospheric river (AR) is a narrow corridor or filament of concentrated moisture in the atmosphere. Other names for this phenomenon are tropical plume, tropical connection, moisture plume, water vapor surge, and cloud band.
Atmospheric rivers consist of narrow bands of enhanced water vaportransport, typically along the boundaries between large areas of divergent surface air flow, including some frontal zones in association with extratropical cyclones that form over the oceans.
Atmosphärische Flüsse (engl. atmospheric river, AR) ist die Bezeichnung für 400 bis 600 km breite und bis zu mehrere tausend km lange Bänder feuchtigkeitsgesättigter Luft aus den Äquatorialregionen in ca. 1 bis 2,5 km Höhe. In ihnen findet der größte Teil des Feuchtigkeitstransports in der Atmosphäre außerhalb der Tropen statt.
Atmospheric rivers are relatively long, narrow regions in the atmosphere – like rivers in the sky – that transport most of the water vapor outside of the tropics. These columns of vapor move with the weather, carrying an amount of water vapor roughly equivalent to the average flow of water at the mouth of the Mississippi River. When the atmospheric rivers make landfall, they often release this water vapor in the form of rain or snow.
The term atmospheric river is used to indicate narrow, elongated corridors of concentrated moisture transport associated with extratropical cyclones. Atmospheric rivers are the largest transport mechanisms of freshwater on Earth. This moisture transport occurs under particular combinations of wind, temperature, and pressure conditions. Atmospheric rivers are typically located within the low-level jet, an area of strong winds in the lower levels of the atmosphere, ahead of the cold front in an extratropical cyclone.
An atmospheric river is a recently coined weather feature that is both a necessity and, all too often, a destructive menace particularly for those near the West Coast of the United States.
Put simply, an atmospheric river (AR) is a thin, but long plume of moisture in the atmosphere that stretches from the tropics or subtropics into higher latitudes.
The term was first used in a 1994 research paper and is now widely used by meteorologists.
( http://onlinelibrary.wiley.com/doi/10.1029/94... )
A more recent study published in August 2015 by the University of Reading and University of Iowa
( http://journals.ametsoc.org/doi/abs/10.1175/B... )
questions whether the term "atmospheric river" is misleading.
The study argues that the AR may not be so much a moisture pipeline from the tropics or subtropics, as previous conceptual models, but rather simply a "footprint" of moisture ahead of the cold front.
Explosive cyclogenesis (also referred to as a weather bomb, meteorological bomb, explosive development, bomb cyclone or bombogenesis) is the rapid deepening of an extratropical cyclonic low-pressure area. The change in pressure needed to classify something as explosive cyclogenesis is latitude dependent.
related discussion: bomb cyclone / bombogenesis event