“It is the life of the crystal, the architect of the flake, the fire of the frost, the soul of the sunbeam. This crisp winter air is full of it.” ~ John Burroughs

All eyes should be looking skyward and all umbrellas prepare to come forth from hiding as the peak of another system moves toward our neck of the woods. If all goes as forecast, arrival time is estimated for today, Thursday; to be more specific, late morning over Santa Barbara County, during the afternoon in Ventura County, finally reaching Los Angeles County in the evening. The name and potential for these rains are unique. Okay, we are ready – bring on the rains!

This weather event is one of those so-called “Pineapple Express” atmospheric rivers that take shape over Hawaii and head towards California. Due to this year’s weak La Niña, the late arrival as such was predicted by the NWS. Originating in the Gulf of Alaska and setting up off the Pacific Northwest, its circulation swoops down, gathering up the extremely moist air in the Hawaiian Islands. In doing so, an atmospheric river is formed that can transport 10 to 20 times as much water volume as the Mississippi River and has been responsible for some of California’s most damaging winter storms.

Atmospheric rivers are a concentrated stream of water vapor in the middle and lower levels of the atmosphere. Visualize a continuous conga line of moisture streaming across the ocean without interruption until it encounters an obstacle such as the coastal ranges in California. Our so-called “obstacle” is the San Gabriel Mountains and here the atmospheric river drops buckets full of water, i.e. rain!

Some atmospheric rivers are weak and produce beneficial rain and some are larger and more powerful and produce extreme rainfall (plus floods and mudslides). Most importantly, fresh water supplies in California are replenished as reservoirs fill and slow-to-melt snowpacks form; locally, we hope for local wells to fill.

An interesting side note: The name Pineapple Express was used by sailors to describe the fast winds that propelled their ships from the Hawaiian Islands towards the West Coast. Aboard were the mostly unheard of and delicious fruit … pineapples.

Thus far, beyond the weekend two more storms are lurking in the forecast. One will stay north and the other east; so, presently and once again, my umbrella awaits the storm.

Sue Kilpatrick is a Crescenta Valley
resident and Official Skywarn Spotter for the
National Weather Service Reach her at suelkilpatrick@gmail.com.