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This is a sobering fact. For the first time since they began keeping records in 1850, San Francisco received no precipitation during the month of January. Zero point zero. In all previous droughts, even just plain fluke years, California's traditionally wettest month always found at least a little something for San Francisco. It is surrounded by water, after all. The city's longterm average for the month is about 4.5 inches, but of course California doesn't really have average rain and snowfall years, it has peaks and valleys and extremes that average out to just enough. The time, in January the meters hit flat bottom in San Francisco, Santa Cruz and other spots around the Bay Area.
As the month came to a close, the second big snowpack measurement of the year in the Sierra Nevada delivered more bad news. The seven inches of snow on the ground at Echo Summit, containing just 2.3 inches of water after it melts, is down substantially from December and sits at just 12 percent of historical average.
Meteorologist Eric Holthaus mused on what it all means for Slate with a couple of days left in January.
California’s epic drought is about to set another seemingly unbreakable record….
And it’s not just San Francisco. In most of northern and central California—the hardest hit regions of the state’s drought—rainfall in 2015 has been less than 2 percent of normal.Any hopes the state had of finally turning the corner on its oppressive, possibly climate change–fueled megadrought have withered like the Sacramento River. Progress made in refilling the state’s largest reservoirs thanks to a series of major December storms has stalled, and key rainfall indices are back to being below normal. Snowpack in the Sierras, which supplies more than 60 percent of the state’s water resources, is down to a dismal 25 percent of normal. New data released by the National Drought Mitigation Center on Thursday showed 40 percent of the state is now classified as “exceptional drought,” the most severe category.
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As the drought plods along, the impact on sensitive industries like agriculture has continued to worsen. This winter, the California salmon industry was decimated by warmer-than-normal water in the state’s lakes and streams, reports Capital Public Radio in Sacramento. Meanwhile, the Sacramento Bee reports that the state is considering temporary dams on the vulnerable Sacramento–San Joaquin Delta in a desperate attempt to keep saltwater from encroaching inland into sensitive wetlands and the state’s drinking water supply.
So yeah — the drought is not just still with us. The outlook grows bleaker the further we get into the winter without cooler temperatures and an atmospheric river or two or three of free water lining up out in the Pacific. Luckily, there looks to be an "atmospheric river event" headed toward Northern California this week. From Stanford Ph.D. candidate Daniel Swain at his California Weather Blog:
As seems to have become the theme over the past few years, an intense precipitation event now appears likely to immediately follow an extraordinary dry spell across Northern California. Confidence has been growing in recent days that another extremely moist plume of subtropical moisture will take aim at NorCal during the first week in February, bringing heavy to excessive precipitation to at least the far northern part of the state.
Recent numerical model runs have been starting to shift this atmospheric river further south along the California coast, meaning that places at least as far south as the Bay Area are likely to see significant precipitation over the next 7-10 days. While there’s still quite a bit of uncertainty regarding the details of this upcoming pattern change, it’s fair to say that someone along the West Coast is going to get a serious soaking, and the focus may well be the northern 1/3 of California. Simulated rain totals for a ~7 day precip event have been very impressive for the North Coast, actually exceeding 20-25 inches of liquid in a couple of recent GFS runs (which is about as I as I can recall having seen in a global model, though it’s possible this could be at least partly due to the recent increase in GFS horizontal resolution). Atmospheric rivers are certainly capable of delivering that kind of precipitation intensity in NorCal, but the question more than a few days out is always where exactly the associated moisture plume will come ashore–and whether it will stall out over a particular region for an extended period of time, raising flooding concerns. At this point, it’s still to early to discern the details, but given the impressively juicy airmass that next week’s storms are likely to tap into I would not be surprised if at least some portion of NorCal was dealing with some significant flood concerns within 7-10 days.
All signs say that Southern California will miss the benefits of this particular atmospheric river, if that's what it turns out to be. Also from the CA Weather Blog:
In great contrast, the southern 1/3 of the state is likely to remain completely dry (and very warm–perhaps near 80 F!) for the duration of this storm sequence. Also, it’s worth noting that sea surface temperatures immediately offshore of California remain extremely elevated–and are locally more than 3-4 F above average for this time of year. These near-record temperatures could provide some extra moisture to the incoming storm systems, as occurred during the December storm sequence in NorCal.
This reaction from the National Weather Service up there:
Amazing! 16 day #GFS shows 15-25" rain total in NorCal with dry conditions for large portion of SoCal! #cawx pic.twitter.com/R95N7qG3hm
— NWSBayArea (@NWSBayArea) February 1, 2015Here's a look at the Pineapple Express pointing at California. Even I can see this one.
Can't ask for better setup for enormous rainfall totals over NorCal & now linto Bay Area in 5+ days #pineapples pic.twitter.com/cs1vT9MDIA
— Ryan Maue (@RyanMaue) February 2, 2015Drought watcher Peter Gleick points out that even the positive scraps of news about California's water situation really aren't that positive. The rain year that ended with September officially sucked, and the current rain year (starting Oct. 1) is starting out badly, since it comes on top of several years of previous bad and with abnormally warm temperatures in the Sierra Nevada and across much of the state.
California’s drought is the result of several factors: how much precipitation we receive in rain and snow; how much water is available after taking into account reservoir storage, soil moisture, and groundwater; additional losses of water due to higher than normal temperatures (the past three years have been by far the hottest in California’s record); and the human demand for water. If all of these factors are included, the current drought in California can be considered the worst in recorded history.
And it isn’t over yet.
