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The natural world. Looking pretty for 3.5b years.

A "River" Returns

Author: Hugh Bollinger/Wednesday, April 11, 2018/Categories: natural history, photography, sustainability, environment, climate change


                                   Atmospheric River, April 6, 2018 (credit: NCEP &

California's rainy season is almost over but an atmospheric river, commonly called a Pineapple Express, just hit the State. The National Atmospheric and Oceanic Administration (NOAA) released a radar image of the entire weather system stretching from Hawai'i and affecting the length of the California coastline.


                                              Atmospheric River, April 6, 2018 (credit: NOAA)

According to NOAA:

the image shows the total precipitable water (TPW) being carried to the West Coast mid-day, April 6th. The Agency's researchers used data from the Global Forecast System to run a predictive model for the entire coast. "Precipitable water" is an estimate of how much moisture would be present in the atmosphere if all of the water vapor in a column of air above you fell as rain. The darker blue shades show where the atmosphere was saturated in moisture, while grey-black areas are regions where the atmosphere was dry.

The atmosphere above the tropical Pacific always carries moisture but a narrow bridge connects the tropics to the West Coast. Such "bridges" become rivers of moisture when the air flows from the region around Hawaii directly towards the West Coast. Rainfall totals varied with the Sierra Nevada mountains receiving additional snow while the charred landscapes created by the recent Thomas Fire, the largest in California's history, were luckily sparred heavy rains and flooding. Yosemite National Park was closed due to the potential for floods in the world famous valley.


The University of California created a short video about atmospheric rivers and their importance to the State and the West Coast region in general:

A big question remains as to how climate change will enhance or reduce these powerful and important weather events.



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