March 07, 2016

Drought Buster Hits California

The multi-year drought in California is rapidly being dissipated by a tremendous onslaught of precipitation.  Major reservoirs will soon be at normal levels, near surface soil moisture is being replenished, floods and power outages are occurring, and the snowpack is surging to well above normal.

After a relatively dry February, substantial precipitation fell during the past week (see map of cumulative 7-day precipitation), with 5-6 inches over the CA coastal mountains and up to 10 inches in the Sierra.

The two biggest reservoirs in California are Lake Shasta and Lake Oroville; both are well above last year's level and surging upwards (see below). Lake Shasta in now at 87% of normal.  In one week, I expect both will be above normal (top of the blue area).  A huge change.

 The NOAA crop soil moisture index is now above normal in central and northern CA (see below)
 And streamflows over most of the state are at or above normal (way above normal in the northern half). Snowpack in the Sierra is well above normal.

Yet the torrents from the sky are not over.  Not even close.  The worst (or best) is yet to come!  Here is the forecast cumulative precipitation for the next 7.5 days. Wow.  The West Coast gets hammered, particularly California, with up to 10-15 inches in the Sierras and mountains of northern CA.

And the extended model forecasts beyond that show even more!

So with massive precipitation, restoration of soil moisture in the northern 2/3rds of the state, above normal streamflow, and above normal snow water content in the mountains, what is the NOAA Drought Monitor showing over California?

Exceptional drought....the absolute worst...over half of the State, with the rest in extreme and severe drought.  Can you imagine if California wasn't floating away with heavy rain?   What would drought monitor show then?    One shudders just thinking about it.

Announcement: Public Talk: Weather Forecasting: From Superstition to Supercomputers

I will be giving a talk on March 16th at 7:30 PM in Kane Hall on the UW campus on the history, science, and technology of weather forecasting as a fundraiser for KPLU. I will give you an insider's view of the amazing story of of weather forecasting's evolution from folk wisdom to a quantitative science using supercomputers. General admission tickets are $25.00, with higher priced reserved seating and VIP tickets (including dinner) available. If you are interested in purchasing tickets, you can sign up here



  1. To be fair, that Drought Monitor snapshot is from March 1st, released on the 3rd -- i.e. before the most recent deluge. Let's see what they show on the next couple releases. But yeah, I bet it doesn't go down much.


  2. I'm curious, do you have any insight into how the aquifer levels react to rain events like this?

    A cursory review of some USGS data looks like a specific well in Sacremento has recovered 50 ft of water since November, but is 90ft below 1988 levels.

    How are aquifer levels used in the drought survey?

    My understanding has been the continual drop in aquifer levels is the larger issues in regard to California's and the rest of the worlds unsustainable water consumption.

  3. In fairness, Cliff... there are still a number of reservoirs that are significantly under historical average:

    I agree, the drought monitor blows things out of proportion, but California is one situation where they are not nearly out of the woods, yet.

  4. Cliff - I'm curious about the drought monitor. Are they also monitoring ground water, or just soil moisture, or is it some black magic voodoo wizardry formula that nobody except one dude somewhere knows? I could see saying "Well, we got 10" of rain this month. Drought over!" leading to some pretty severe disappointment in a few short weeks/months when it's as dry as ever and none of the underground water supplies really got replenished.

    I've thought/wondered the same about ours here in WA. Would saying "Drought over! Resume your normal water-usage-ignorant activities!" prematurely ultimately cause more harm than good if this is a seasonal abnormality and the regularly schedule programming resumes this summer? Would that be a bad thing?

  5. They have opened the flood gates at Folsom to make sure they have enough capacity for the upcoming rains.

  6. "
    jqkeller said...
    I'm curious, do you have any insight into how the aquifer levels react to rain events like this?

    A cursory review of some USGS data looks like a specific well in Sacramento has recovered 50 ft of water since November, but is 90ft below 1988 levels.

    Actually, NAVD 1988 is not the 1988 level of that well, NAVD 1988 is SEA LEVEL on the North American Vertical Datum of 1988. The left axis of the plot you refer to shows depth below the land surface (which is at 323 feet above sea level according to, the right axis shows water elevation above sea level. That site only appears to have data back to 2012, so there's no info about what the level was in 1988 or anytime before 2012.

    However, the water level was about 110 ft higher in early 2012 (the first year of the 4-year drought) than it is now!

  7. Getting back to the PNW, NASA put out a press release about their efforts in watching yesterday's (7 March) storm system:

  8. Can someone explain the drought monitor? Is is feast or famine?

  9. The aquifers in the Central Valley which started out with fossil water have been collapsing as water has been withdrawn. It's very unlikely they can expand like a sponge because of the weight of the overlying soil. Thus the aquifer capacity has been seriously compromised. If the drought continues after this El NiƱo many farmers will still be without water. Some previous California droughts have lasted as long as 30-50 years so all bets are off.

  10. To be fair, the drought monitor map is updated on Thursday mornings, for the week through the prior Tuesday. So that drought map is for March 1, which was well before all the recent rain. This Thursday we will see the map for March 8, which should show a different picture.

  11. Where are you getting that the SWE is above normal? I am looking at the snotel narrative; one basin is 102% and the others range from 94 to 99%. Normal maybe, but certainly not above normal.

  12. I'm glad that I didn't put money on the ridge persisting through March although the California February dryness was a bit of a surprise. It's worth noting that in the midst of that dryness, heat records were set or approached which doesn't help moisture availability.

    Earlier analysis of potential drought recovery in California indicated that even a supremely wet winter wouldn't dig the state completely out of it's hole. GRACE data show good conditions for shallow and medium soil moisture but deficits at deeper levels -- "shallow groundwater".

    I imagine aquifers are a long ways from recovery from natural drought not to mention human accelerated extraction.

    Looks like another wet week ahead for California and then possibly back to summer for them.

  13. Welp, I just checked the latest CA drought monitor (now through March 8). Apparently they still see no sign of let-up from the drought. That IS bizarre, given all the data points Cliff outlined above.

  14. In the words of Rahm Emanuel, "You never let a serious crisis go to waste. And what I mean by that it's an opportunity to do things you think you could not do before."
    Most of California's politicians just see this drought as an OPPORTUNITY to consolidate power and control. For this reason, they are not eager to declare the crisis as over.

  15. The Drought Monitor is just one of many facets of the Obama administration's global warming propaganda war. It's not about science. It's a tax scheme, which is why "progressives" support it.


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