Think on These Things
January 22, 2014
Bitterly cold air is again settling southward from the Arctic into a large part of the Eastern states. Unlike the outbreak from early January, this time the cold will have more staying power.
Into the first part of next week, the polar vortex will hover just north of the United States border causing waves of frigid air to blast into the Midwest and much of the East.
The polar vortex is a commonly used term among the meteorological community to describe an intense storm with frigid air and strong winds that spends much of its time above the Arctic Circle. Occasionally, during the autumn, winter and spring, this storm can dip farther south, approaching the mid-latitudes.
While much of the United States has experienced a weather year with fewer extremes and an easing drought, the record-breaking California drought – the worst since 1895 – is not leaving the region anytime soon, according to climatologists.
The unseasonal balmy but dry weather is the result of an equally unprecedented high pressure ridge lurking offshore and blocking the typical winter storms needed to drop precipitation all along the West Coast.
This ridge has persisted for 13 months and the longer it lingers, the less likely it is to leave, points out climatologist Brian Fuchs, from the National Drought Mitigation Center in Lincoln, Nebraska. This high pressure ridge system is feeding on itself, “creating a sort of perfect environment for perpetuating the dry conditions” it creates, he says.
High-pressure systems are not uncommon, but it is abnormal for them to hang around uninterrupted for so long. “This makes it even harder as winter storms approach for them to break through and change that pattern,” he adds.
Yes, 2013 was the driest year in California since the 1840s, when recordkeeping started. But Lynn Ingram, a climate expert at the University of California, Berkeley, thinks this could be the Golden State’s driest year in half a millennium.
“This could potentially be the driest water year in 500 years,” said Ingram, a paleoclimatologist.
She studies fossilized records of earth’s climate going back millions of years — layers of rock or sediment, shells, microfossils — or other indicators, including rings in trees, seeking a long view.
Based on the width of old tree rings, Ingram concludes California hasn’t been this dry since 1580.