Measuring atmospheric rivers - CBS News 8 - San Diego, CA News Station - KFMB Channel 8

Measuring atmospheric rivers

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SAN DIEGO (CBS 8) - Imagine getting rain heavy enough to cripple freeways, flood valleys and resolve droughts in a matter of days. We're talking about the equivalent of 7 1/2 to 15 times the flow of water at the mouth of the Mississippi River.

It's happened before and it will happen again - this rain event comes from what researchers call an atmospheric river.

"On one hand they can be a hazard, but important for water supply that we generate here in the West," research meteorologist Dr. Dan Cayan said.

These atmospheric rivers tend to be most active winter through spring, which is why local researchers from Scripps Institution of Oceanography and NOAA, the National Oceanic & Atmospheric Administration are climbing to new heights -- 45,000 feet up for the best chance at collecting valuable data.

"Our colleague Marty Ralph, who's a researcher here, leads a center studying these extreme weather events, the Center for Western Water and Weather Extremes is probing these streams of fast flowing air," Cayan said.

Last week during the major downpour over the Pacific northwest, research meteorologist Dr. Marty Ralph and his team flew several hundred miles offshore, using specialized instruments to collect data, making this the first ever flight into an atmospheric river with NOAA aircraft.

"We ended up leaving with cloudiness and bumps, flew well offshore, we ended up with 23 dropsondes we released into the storm," Ralph said.

What good is an atmospheric river to San Diego when we have a ridge of high pressure blocking the wet weather?


"Any relief to the entire system is good for us. Agriculture, water supply-wise, and then there's hydro power, which we depend on in the summertime," Cayan said.


Despite receiving several inches of rain from last week in Northern California, atmospheric experts are saying we'd need four or five of these events to get out of a drought for the entire state of California.


"We still have about 75 percent to get back to normal," Cayan said.


That's why these offshore flights will be helpful when it comes to predicting what the next atmospheric river will deliver. In the past, forecast landfall positions have been off by as much as 300 km. That distance is equivalent to Santa Barbara to San Diego.

"As a forecaster, one of the challenges is are the tools I have to predict the phenomena, but can it predict at the right time, right place, right strength?" Marty said.

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