It’s been a sunny and warm week here, which may make some of you envious, but it comes at a price:

Persistent zone of high pressure blamed for West Coast drought

As California struggles through a run of historically dry weather, most residents are looking at falling reservoir levels, dusty air and thirsty lawns.

But meteorologists have fixed their attention on the scientific phenomenon they say is to blame for the emerging drought: a vast zone of high pressure in the atmosphere off the West Coast, nearly four miles high and 2,000 miles long, so stubborn that one researcher has named it the “Ridiculously Resilient Ridge.”

The mass of high air pressure has been blocking Pacific winter storms from coming ashore in California, deflecting them into Alaska and British Columbia, even delivering rain and cold weather to the East Coast. Similar high-pressure zones pop up all the time during most winters, but they usually break down, allowing rain to get through to California. This one has anchored itself for 13 months, since December 2012, making it unprecedented in modern weather records and puzzling researchers.

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With each passing week, California’s lack of rainfall becomes more serious.

Last year was the driest calendar year in recorded history in California in most cities, with records going back 160 years. The first snowpack reading in the Sierra Nevada this month found a snowpack of just 20 percent of normal.

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