I'm Dave Thurlow for the Mount Washington Observatory in North Conway, New Hampshire, and this is The Weather Notebook. Today on the show we talk about a weather phenomenon named after pineapples.
Near the end of last year, when the U.S. West Coast was hammered by storm after storm, the culprit was something called the Pineapple Express. The Pineapple Express is a name given to a fairly frequent atmospheric set-up, which creates the infamous rainstorms along the Pacific Coast. Weatherpeople pointed to it on Pacific Ocean satellite pictures and sure enough, you could see a blotch of thick white clouds running all the way from Hawaii - hence the pineapples - into California, Oregon, and Washington. However, looks can be deceiving.
There was indeed a rich flow of moisture coming from the subtropical Pacific into the West Coast. But satellite pictures used on TV concentrate on ice-crystal clouds that are five miles high. John Monteverdi, a meteorologist at San Francisco State University, notes that the high clouds visible on satellite and the low-level moisture aren't always in synch.
On New Year's Eve last year, San Francisco was socked with more than four inches of rain, as moisture poured into the area at all heights. On January 4, the satellite pictures showed the same set-up; however this time only a tenth of an inch of rain fell. So it takes more than one satellite picture to explain what's going on in the atmosphere. Weather's not only many-splendored, it's also multi-layered and the full extent of the pineapple express is sometimes hidden from view. Our show is written this week by Robert Henson.
Funding for The Weather Notebook is provided by The National Science Foundation. Our show is underwritten by Subaru, maker of the all Weather Legacy. Subaru -- the beauty of All-Wheel Drive.