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California has been stricken by severe drought for years now, to the point that the governor has been required to mandate water rationing. In an Accuweather piece about the storm currently ravaging the west coast of the US, senior meteorologist Alex Sosnowski claims:

The siege of storms has the potential to wipe out or greatly erase the long-term drought conditions in the region.

Is it realistic that this one batch of storms could end the drought?

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    You are asking about this one storm whereas Sosnowski says siege of storms. Please edit your question to remove the discrepancy. – Jan Doggen Jan 9 '17 at 12:40
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    @Jan: Be bold! Go ahead and make these edits. – Oddthinking Jan 9 '17 at 13:25
  • Could we please avoid such loaded terms as "ravaging" and "siege of storms"? OK, I realize you're just quoting that last, but still... – jamesqf Jan 9 '17 at 19:18
  • @jamesqf I don't like "siege of storms" either, it's a bit melodramatic. As for "ravaging," that's fair game if you'd like me to edit it out – TheEnvironmentalist Jan 9 '17 at 22:03
  • @jamesqf Oroville dam (the second largest reservoir in California) is being damaged by the amount of water being released sfgate.com/news/article/… and the amount going in is still 3 times the amount going out. cdec.water.ca.gov/cgi-progs/queryF?ORO water is rising 1 foot every 2 hours, and now 18 feet from the top. – DavePhD Feb 9 '17 at 21:55
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Drought conditions in the United States are monitored by the US Geological Survey (USGS).

See the following link for current California hydrological drought conditions: https://waterwatch.usgs.gov/?m=dryw&r=ca

As of 08 January 2017, only a small area of California, roughly 5%, is in any degree of hydrological drought condition.

According to California government, as of 08 January 2017, on average, reservoirs are 100.63% of their normal level.

The largest reservoir, Shasta, is currently holding 120% of normal (average) amount.

Another factor to consider is the snowpack. Click here for daily snowpack data. As of 09 January 2017, state wide, the snowpack is 126% of normal for this date of the year.


Update 26 January 2017:

On the basis of reservoir levels, soil moisture, stream/river flow, and snowpack, the drought it over, but groundwater levels are still very low in some areas. So on a groundwater basis, which is very important to well water users, there is still a long term drought.

Snowpack is 189% of normal.

Reservoirs are 113% of normal.

Soil moisture is at or above normal in the entire state.

Stream and river flow is at or above normal across the state.

enter image description here

(Figure source)

However, the National Drought Mitigation Center states:

According to the San Joaquin precipitation index (an average across that region), January was the wettest ever observed in 112 years of record, and 4- to 5-year precipitation totals climbed dramatically from approximately the 2 percentile level as of early January to around the 20th percentile through this week. Statewide average snowpack (snow water equivalent) is almost twice normal for late January, and somewhat more than twice normal in the southern Sierra Nevada. Amounts actually exceed those typically recorded April 1 (snowpack climatological maximum). Given these dramatically wet indicators, widespread 1-category improvements were again instituted this week, wiping D4 from the state and restricting D3 to part of southwestern California. It should be noted, however, that to date groundwater levels have not responded as one might expect, and remain critically low. In most of the central foothills on the east side of the San Joaquin Valley, plus a number of other communities and cities across the nearby mountains and valleys, water supply is dependent on groundwater. Thus potable water is still being trucked in to serve residents with dry wells in areas such as Tuolumne County, and the deepest wells may not respond to the recent inundation for many more months.

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    A factor not mentioned is how much of the precipitation can actually be absorbed into the soil, either now as rain, or later when the snowpack melts. At my elevation (4800 ft) and above it's falling on ground that was frozen before the start of Sunday's warm storm, so most everything seems to be just running off. Also a caveat on that snowpack link: notice the wide range of percentages? I suspect that's because this storm was rain below about 9000 ft, and melted a lot of low-elevation snow. – jamesqf Jan 9 '17 at 19:27
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    @jamesqf as of December, no part of California had below normal soil moisture. And by today almost the whole state is above normal cpc.ncep.noaa.gov/products/Soilmst_Monitoring/US/Soilmst/… (click on daily and monthly percentile) – DavePhD Jan 9 '17 at 19:39
  • @jamesqf and DavePhD, so the argument then is that the drought was over before the storms began? When did the drought end? – TheEnvironmentalist Jan 9 '17 at 22:05
  • DavePhD: Certainly wasn't true of the part I frequent. Though admittedly I'm a few miles east of the political state line, I'm still in the geographic & climatic Sierra. So perhaps they're not monitoring around here? It also seems that their soil moisture is not quite I was referring to. It appears to be surface moisture, which can change on a fairly short timescale, not the moisture that percolates from the soil downwards to the water table. – jamesqf Jan 9 '17 at 22:47
  • @jamesqf NASA monitors soil moisture to 3km resolution by satellite smap.jpl.nasa.gov/data Groundwater level is different. That is monitored in thousands of wells by USGS. groundwaterwatch.usgs.gov Groundwater is still low in parts of southern California. – DavePhD Jan 9 '17 at 22:54

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