What is causing the drought in the West? Could it be a jetstream phenomenon connected to the cold winter being experienced back East? Which could be connected to blockages interrupting the polar vortex, causing it to spill southward into places like the Ohio Valley? And could those blockages be connected — as researchers such as Jen Francis contend — to global warming?
In other words — could global warming be bringing us dryness here in California?
The possibility could be a big story, with — as they say in the journalism trade — lots of moving parts.
Many studies have suggested the possibility that global warming could intensity drought in the West, but some of the leading modelers have tried to replicate the causal mechanism without success statistically, resulting in a genuine controversy in the field. In turn, the modelers have been sharply criticized for ignoring crucial factors such as soil mositure, by the likes of Kevin Trenberth, as discussed by Joe Romm in a ClimateProgress report.
Not all climate science is settled to the nth degree. As long as reputable scientists are presenting research disputing the global warming/Western drought connection, the truth of the charge is unproven.
Still, it's hard to avoid the possibility, especially in the High Sierra.
Let me offer an example:
On the shoreline at Lake Tahoe, where snow should be piled high by now, Valerie Chown and her family this week stumbled across a most unusual winter phenomenon.
There, on the beach, was a nude sunbather.
"It was crazy," said Chown, 59, of Los Altos Hills, about the encounter at Secret Cove, where a few too many secrets were revealed, at least for this time of year.
Only in California. That's from Peter Fimrite of the San Francisco Chronice.
The signs aren’t good when the chief of California’s snow survey has to walk over bare ground to take a snowpack measurement in the Sierra Nevada, as Frank Gehrke did Friday near Echo Summit.
Manual and electronic readings up and down the range placed the statewide snowpack at 20% of normal for this date, adding to worries that 2014 could be a bad drought year.
The meager snowpack was not a surprise. Last year was California’s driest in 119 years of records, according to the Western Regional Climate Center in Reno.
This story includes a picture, though it's not much fun. All the officials are looking down:
Meanwhile, as Climate Central reports, the center of the country is being hit hard by an outbreak of the polar vortex, depicted here in a model for January 6 by WeatherBELL Analytics:
Or, more precisely, in the words of Climate Central:
The cause of the Arctic outbreak can be traced to northeastern Canada and Greenland, where an area of high pressure and relatively mild temperatures is set to block the eastward progression of weather systems, like an offensive lineman protecting the quarterback from the other team.
The atmospheric blocking is forcing a section of the polar vortex to break off and move south, into the U.S. The polar vortex is an area of cold low pressure that typically circulates around the Arctic during the winter, spreading tentacles of cold southward into Europe, Asia, and North America at times. Except this time, it’s not a small section of the vortex, but what one forecaster, Ryan Maue of WeatherBELL Analytics, called “more like the whole enchilada” in a Twitter conversation on Thursday.
How cold will it get? Computer model forecasts project low temperatures on Monday night in Washington to drop to near zero, and below zero in Boston and possibly New York City as well. Dayton, Ohio, is likely to see lows from 10-20°F below zero, and parts of Iowa could see temperatures into the minus 30s°F.
This raises the inevitable connection: Is there a Western onnection?
According to Fish Out of Water, for KOS, the answer is…yes:
This image shows that the lower half of the atmosphere above the northeastern Pacific was much warmer and thicker than normal in 2013, blocking jet stream flow that would bring storms to California.
The jet stream tracked far north of normal in 2013, leaving the west coast of the U.S. in drought. A dome of warmer than normal air and higher than normal pressure pushed west coast storms towards Alaska.
But is this atmospheric high pressure system the cause of California's drought, or a consequence of an oceanic pattern?
An alternative view puts responsibility at the feet of the Pacific Decadal Oscillation, better known as the PDO. As Bill Patzert told the LA Times:
In the cycle's negative phase, the surface waters of the western Pacific warm while the eastern Pacific cools, rather like a big La Niña that pushes the jet stream and the storms it carries to the north of California.
The reverse ocean temperature pattern prevails when the oscillation is in the positive phase, producing wetter, El Niño-like conditions.
For more than a decade, the oscillation has tended toward the negative. "Since 1997-98 more or less, we've been in a dry pattern" in the West, Patzert said.
A glance at the weather service records backs that up. Of the 10 driest years recorded in downtown L.A., two — 2013 and 2007 — have occurred in the last decade.
Which is to say — natural variability. And the KOS blogger does admit the possibility, and fall into speculation in the conclusion to his post:
I suspect the weakening of the thermohaline circulation around Antarctica resulting from the freshening of the waters is driving an acceleration in the trade winds and the ocean currents. About 20% less water is sinking around Antarctica, so the thermal gradient is increasing around Antarctica. This is paradoxically increasing Antarctic winter sea ice while the global oceans warm up faster than expected.
And he adds:
Of course, there are natural cycles and there's always natural variability.
To which one can only say: Of course.
Frankly, at this point, we can only hope for an outbreak of natural variability — anything to vary the pattern from dryness.
Went to Death Valley after Christmas and was struck by the fact that it seemed only slightly drier than the rest of Southern California. Which usually by now has had more than an inch or so of rain, when absolutely none is foreseen for this month: