Image source: http://www.esrl.noaa.gov/psd/atmrivers/questions/
The storm that hit our coast last week, resulted in power outages to more than 160,000 customers, downed trees that caused a major fire, and extreme wind gusts around Western Washington. For further description of storm effects on areas around Washington, click here.
Warm, moist air was funneled into the West Coast from the tropical Pacific in what's known as an "atmospheric river." Due to the river's weather pattern migrating winds from the southwest (near Hawaii) to the West Coast, the event is often labeled as a "Pineapple Express."
Atmospheric rivers (AR) are relatively narrow regions in the atmosphere that horizontally transport water vapor outside of the tropics. While the shape and size of ARs can vary, they have the potential to create extreme rainfall and floods. These events can disrupt travel, induce mud slides, and cause catastrophic damage to life and property. In November 2006, an AR produced heavy rainfall and devastating flooding and debris flows that resulted in region-wide damage exceeding $50 million (http://www.esrl.noaa.gov/psd/atmrivers/questions/).
So why is understanding atmospheric rivers important?
"Better coupling of climate forecasts with seasonal weather forecasts of ARs can improve water management decisions. Long-term monitoring using satellite measurements, offshore aircraft reconnaissance, and land-based atmospheric river observatories, combined with better numerical modeling, scientific progress, and the development of AR-based smart decision aids for resource managers, will enable society to be more resilient to storms and droughts, while protecting our critical ecosystems" (http://www.esrl.noaa.gov/psd/atmrivers/questions/).
Links for more information about last week's storm:
For more information about pineapple express and atmospheric rivers: