Record snow falls and atmospheric river

Our record breaking current snow has been caused by another “Pineapple Express”, the name for an atmospheric river that forms near Hawaii, pineapple’country. 

That kind of precipitation carries warm, moist air north to the West Coast of North America, where it can drop up to 5 inches of rain a day. 

This large, narrow stream of water vapor up in the sky can stretch to 1,000 miles long and more than 400 miles wide, and on average, carries an amount of water equivalent to 25 Mississippi Rivers, according to Marty Ralph, a researcher and director at the University of California San Diego's Scripps Institution of Oceanography. 

The term atmospheric river was first coined in 1998 by Massachusetts Institute of Technology researchers Yong Zhu and Richard Newell, but ARs had been observed before then. They usually begin life in the tropical ocean regions near the equator, and can bring large masses of warm air and water to areas like North America's west coast. 

As the rivers cross from the ocean to the land and then to the Rocky Mountains, the vapor condenses into precipitation, sometimes dumping a month's worth of rain or snow in a matter of days. In altitude, where snow normally starts falling at 36-37 degrees F, it will still be rain at 30 degrees F as it did few days ago in Park City when that atmospheric river reached us...