Monday, April 21, 2014

Swirling Cyclone Bears Down on California

As I write this, California is being lashed by rain and wind from a storm bringing much needed moisture — but which also threatens to cause some havoc in the form of mudslides and flooding.

Here’s how the National Weather Service in Los Angeles described it in their forecast discussion this morning:

A VIGOROUS WINTER STORM WILL AFFECT THE AREA THROUGH SATURDAY. EXPECT RAIN...MOUNTAIN SNOW...GUSTY WINDS...POSSIBLE THUNDERSTORMS...WATERSPOUTS...URBAN FLOODING...AND MUD AND DEBRIS FLOWS NEAR RESENT BURN AREAS. RAINFALL WILL BE INTENSE AT TIMES. A CLEARING AND DRYING TREND WILL START SUNDAY AFTERNOON. CLEAR WITH A WARMING TREND FOR EARLY NEXT WEEK.

Waterspouts?!

In the gallery above, you won’t see any of those. These images are various satellite views of the swirling cyclone that is bringing both relief and risk to California today and through tomorrow.

The first is a visualization of the storm’s cyclonic winds, as forecast by supercomputers. I chose it to lead off the gallery because it really emphasizes the structure of this powerful storm.

The next three images come from the GOES-13 weather satellite. The first is a true-color image of the storm. Next is a picture that shows water vapor over the Pacific. And in the third, North American is seen in the infra-red portion of the electromagnetic spectrum. I included this one because it shows the broader geographic context — and just how huge the storm is.

After the GOES satellite imagery comes two images captured by NASA’s Aqua satellite on Thursday, February 27. The first is in natural color, and it too emphasizes the sheer size of the storm. But I’m also intrigued by the much smaller cyclone-like pattern of clouds to the east, closer to the West Coast.

The second Aqua image is in false-color. Based on light in the visible part of the electromagnetic spectrum and short-wave infrared, this color scheme is good for revealing snow and ice — including small ice crystals in high-level clouds, which appear reddish-orange or peach. (This is the 3-6-7 band combination of Aqua’s MODIS instrument. For more detailed information, go here.)

Lastly, an image showing total precipitable water over the Pacific. The colors give an indication of the amount of atmospheric water vapor from the top of the atmosphere to the surface. It really emphasizes the tropical source of the moisture now dumping on California.

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