BestsellerMagazine.com - CATEGORY Breaking news: TITLE
In what is being called “The Big Dark” by some, the 5,000 mile long atmospheric river is a band of water vapor that’s expected to drop a lot of rain and snow in the Northwest. Josh King has the story (@abridgetoland).Media: Buzz 60
They're called "atmospheric rivers," and these supercharged storm systems are known for delivering massive amounts of snow and rainfall in a matter of days on the West Coast of the United States.
The long plumes of water vapor in the atmosphere are like rivers in the sky—250 to 375 miles wide on average. On the West Coast, they most often originate in the South Pacific, and as they travel from the tropics across the ocean, they collect incredible amounts of moisture, and funnel it into cities like San Francisco, Sacramento, Portland, and Seattle, where the runoff systems are often unequipped to deal with the days-long deluge.
An atmospheric river carrying moisture from as far away as Hawaii to the West Coast is what's known as a "pineapple express."
When an atmospheric river hits landfall, the water vapor rises and cools, unleashing precipitation. The amount that falls is dependent upon the strength of the storm and its moisture content.
National Weather Service meteorologist Brian Garcia likens being at the core of one of these storms to standing under a waterfall.
"Some are intense and will put immense amounts of water on you, while others can be seemingly trickles and only bring a little," Garcia says. "Either way, if you move away from the core of the waterfall, it's more of a spray."Photo: National Weather Service Image 1of/3
CloseImage 1 of 3
A satellite image from Monday afternoon shows visible water vapor over the western half of the United States. The storm system moving inland over the Northwest was already bringing high winds and rain to the Seattle area and beyond.less
A satellite image from Monday afternoon shows visible water vapor over the western half of the United States. The storm system moving inland over the Northwest was already bringing high winds and rain to the... more Photo: National Weather Service Image 2 of 3
One time use: Researchers at Scripps Center for Western Weather and Water Extremes mapped the atmospheric rivers that made landfall on the U.S. West Coast from Oct. 1, 2016, to March 31, 2017.
One time use: Researchers at Scripps Center for Western Weather and Water Extremes mapped the atmospheric rivers that made landfall on the U.S. West Coast from Oct. 1, 2016, to March 31, 2017.Photo: Scripps Institution Of Oceanography At UC San Diego / Center For Western Weather And Water Extremes Image 3 of 3
A graphic from the National Weather Service describes the science behind atmospheric rivers.
A graphic from the National Weather Service describes the science behind atmospheric rivers.Photo: NOAA What's an 'atmospheric river' and why do we get these supercharged storms? 1 / 3 Back to Gallery
For more perspective, the strongest atmospheric rivers carry an amount of water vapor equivalent to about 7.5 to 15 times the average flow of liquid water at the mouth of the Mississippi River, according to the National Weather Service. When a sytem of this strength stalls over an area, it can dump tremendous amounts of rainfall, causing flooding, or immense amounts of snowfall, covering roads.
An unprecedented number of these fierce storms battered the Western United States and especially Northern California in the 2016–17 rainy season, filling up reservoirs and piling up a record-breaking snowpack in the Sierra Nevada mountain range. These atmospheric rivers were hailed as ending California's five-year drought.
According to researchers at Scripps Institute in San Diego, a total of 45 pummeled the west coast between Oct. 1, 2016, and March 31, 2017. Of these, three were categorized as extreme, 12 were strong, 20 moderate and 11 weak.
BestsellerMagazine.com, set News , Photos, Profile, Video, Artist & Celebrity World complete.
Source : http://www.sfgate.com/news/article/atmospheric-river-storm-rain-snow-floods-12356694.php