BEFORE & AFTER Atmospheric rivers impact

“Before” satellite image – 3 weeks before the rains came

After at least nine atmospheric rivers in a little more than three weeks dumped more than 30 trillion gallons of water on California, the state’s landscape of deep valleys, tall mountains and rugged coastlines has been visibly altered. Those changes, which extend well out into the Pacific Ocean, can be vividly seen from space now that the storm clouds have cleared.

Satellite imagery from before and after the atmospheric rivers, which are narrow bands of extreme moisture that produce heavy rain and snow, tell the story of a state that has seen devastating flood damage, rising reservoirs, and billions of gallons of water lost to the ocean after a three-year drought.


Understanding How Atmospheric Rivers Control Most of Earth’s Precipitation

The rain currently pummeling coastal California is relieving parched crops. It’s also a nuisance that’s delaying flights, uprooting trees, and causing devastating flooding.

Atmospheric rivers (ARs) are to blame. These regions of humid air flow from the tropics into colder climates as strong winds, and condense when they encounter mountains. The warm air rises and cools over elevated land, forming clouds that dump rain and snow onto the earth below. ARs originate in the tropics because warm air holds more moisture.

“Atmospheric rivers are literally rivers in the sky, the rivers of water vapor that transport massive amounts of water in the atmosphere,” Marty Ralph, a hydrometeorologist, tells Popular Mechanics…To predict precipitation over the West Coast, Ralph and a co-researcher began studying atmospheric rivers. “We’re essentially measuring the atmospheric river itself over the ocean,” Ralph says. “We need to know the vertical details of the AR and [analyze] the lowest 10,000 feet.” Very little data exists on this region, because clouds tend to block ARs from a satellite’s view.

So, Air Force planes do the job; they fly into atmospheric rivers, dropping 10–12 little sensors that are about the size of a Coke can and equipped with parachutes. As they descend, the sensors measure temperature, pressure, wind, and moisture, and then communicate that data back to the airplane via radio. Next, the airplane sends the data via satellite to “a big bucket of weather data that weather prediction models around the world draw from to start the next forecast,” Ralph explains.

Meteorology has advanced so much in recent decades. It boggles the mind. Though there remains insufficient connections between informed professionals and a public which might live a safer, more productive life with more information available…in understandable form.

It never ends…Storm Dennis follows Storm Clara

Click to enlarge

Storm Dennis, one of the deepest low-pressure centres to have formed in recent years, has brought severe weather to Iceland and many western and central parts of the UK.

Some of the regions now being affected by Dennis were also hit by a preceding storm, Ciara, which brought stronger winds than Dennis but less rain. Nevertheless, rivers were already full and the ground saturated before Dennis’s arrival.

The military has been called in provide assistance in parts of northern England, where rivers have overflowed in recent days.

Click through and check out the photos. The worst waves haven’t hit land [yet?]. They’re up to 100 feet high.

Atmospheric river storms are getting stronger

Atmospheric rivers are long, narrow bands of moisture in the atmosphere that extend from the tropics to higher latitudes. These rivers in the sky can transport 15 times the volume of the Mississippi River. When that moisture reaches the coast and moves inland, it rises over the mountains, generating rain and snowfall and sometimes causing extreme flooding.

Recently…a team of researchers from Scripps Institution of Oceanography and the Army Corps of Engineers in the first systematic analysis of damages from atmospheric rivers due to extreme flooding. We found that while many of these events are benign, the largest of them cause most of the flooding damage in the western U.S. And atmospheric rivers are predicted to grow longer, wetter and wider in a warming climate.

RTFA. More info. A scale for evaluating the dangerous potential in these rivers. Another wake-up call for this nation.