In the coming days, the northern Sierra Nevada in California is going to get pounded with a literal rushing “river” of moisture that promises to dump upwards of five feet of snow in some of the mountain range’s higher elevations and as mush as two feet of rain in parts of nothern California.
Within a few days, the mighty system will sweep down into some of the more drought-parched regions of southern California, too.
“This is what we’re supposed to be getting,” Johnnie Powell, a meteorologist at the National Weather Service, told the Los Angeles Times.
“After six years of a drought, I love saying that. This is normal rain and snow that we’re supposed to be getting in December and January.”
So, the end of the five-year California drought is nigh, right? Well, no. It’s not nigh.
The Great California Drought’s end is not nigh for the simple reason that what we are witnessing on the Left Coast is weather. And while an extended “weather” feature like drought is a function of climate, “weather” all by itself is not.
The difference between “weather” and “climate” is a fundamental meteorological distinction.
“Weather is the daily condition of the atmosphere, (including) specifics of temperature, humidity, wind and precipitation,” said Arizona State Climatologist Nancy Selover.
“Climate is the long-term average and extremes of those daily values.”
It is possible, but far from certain, that the enormous “atmospheric river” of precipitation now beginning to batter California is the return to “normal” that Powell of the NWS describes.
That hopeful anticipation is bolstered by other meteorological developments. Northern California also experienced its wettest October in 30 years. And, as reported by the National Weather Service, the same region experienced above-average precipitation in December.
So, is California – and, by extension, the Southwest – out of the drought-woods?
Wet weather is nice, but it would take a long-term trend of similar weather patterns for it to constitute a change in climactic conditions away from the lingering pattern of chronic drought that has left its mark in California for the last five years, as well as in the Southwest for going on 17 years.
And while some parts of the Sierra Nevada range may be getting crazy-deep snow deliveries, the distribution of moisture is far from universal. Despite all that October and December rain and snow, for example, the California-wide snowpack has been measured at just 70 percent of normal, as reported by the California Department of Water Resources.
Of course, that was before that megillah of a storm system began hitting the California northlands – a storm system that, while enormous, still constitutes nothing more than a very encouraging weather pattern.
“We often say, ‘Climate is what we expect, but weather is what we get,’” said Selover.