Ongoing California Drought May Be Most Severe Since the 16th Century

[donsutherland1]

At least that's the argument published in a letter to  Nature Climate Change.

 

Excerpts:

 

California is currently experiencing a record-setting drought that started in 2012 and recently culminated in the first ever mandatory state-wide water restriction¹. The snowpack conditions in the Sierra Nevada mountains present an ominous sign of the severity of this drought: the 1 April 2015 snow water equivalent (SWE) was at only 5% of its historical average². In the Mediterranean climate of California, with 80% of the precipitation occurring during winter months, Sierra Nevada snowpack plays a critical role in replenishing the state's water reservoirs and provides 30% of its water supply³...

 

ur error estimation indicates that there is a possibility that a few (primarily sixteenth century) years exceeded the 2015 low, but the estimated return interval for the 2015 SWE value — as calculated based on a generalized extreme value (GEV) distribution (Supplementary Information) — is 3,100 years and confirms its exceptional character. GEV-estimated return intervals can have large confidence intervals (Supplementary Fig. 2), but the 2015 SWE value exceeds the 95% confidence interval for a 500-year return period (Supplementary Fig. 3). In comparison, the previous lowest SWE reading (in 1977) exceeds the 95% confidence interval for only a 60-year return period. We also find that the 2015 SWE value is strongly exceptional — exceeding the 95% confidence interval for a 1,000-year return period — at low-elevation Sierra Nevada sites where winter temperature has strong control over SWE⁹, but less so at high-elevation sites, where it exceeds the 95% confidence interval for only a 95-year return period (Supplementary Information and Supplementary Fig. 2).

 

http://www.nature.com/nclimate/journal/vaop/ncurrent/pdf/nclimate2809.pdf

 

Hopefully, the ongoing El Niño will initiate a recovery from the ongoing drought.

[Smoked]

Southwest CA has done well recently setting monthly records in some spots for the months of July and now September, normally very dry months. Hopefully this is a sign of things to come.

[thewxmann]

  On 9/19/2015 at 4:42 AM, Smoked said:

Southwest CA has done well recently setting monthly records in some spots for the months of July and now September, normally very dry months. Hopefully this is a sign of things to come.

 

I'm hoping that some of that can spread to Northern California. This is ridiculous how little of their rain has reached our area.

[Smoked]

  On 9/19/2015 at 8:32 AM, thewxmann said:

I'm hoping that some of that can spread to Northern California. This is ridiculous how little of their rain has reached our area.

 

Past strong El Ninos have tended to produce above normal precip for central and northern CA so hopefully it works out!

[aslkahuna]

Summer rains (rare in CA)are not usually effective in drought mitigation since they occur too quickly and too spatially limited. What is needed are duration rains and a heavy snowpack in the northern Sierra.

Steve

[A-L-E-K]

el nino winter can't get here quick enough

 

[Jonger]

  On 9/28/2015 at 1:11 PM, A-L-E-K said:

el nino winter can't get here quick enough

 

 

Every time I check a 384 hr accumulation map, it's the same story -- nothing on the west coast. It's uncanny how that area of the western hemisphere seems to be exclusively left out of most precipitation. 

[A-L-E-K]

  On 9/28/2015 at 2:33 PM, Jonger said:

Jonger, on 28 Sept 2015 - 09:33 AM, said:

Every time I check a 384 hr accumulation map, it's the same story -- nothing on the west coast. It's uncanny how that area of the western hemisphere seems to be exclusively left out of most precipitation. 

 

it's still pretty typical this time of year, going to be a different story if the map looks similar in a couple months

[thewxmann]

  On 9/28/2015 at 6:16 PM, A-L-E-K said:

it's still pretty typical this time of year, going to be a different story if the map looks similar in a couple months

 

I swear the map looked just like that in the last two Januarys.

[salbers]

Has there been a dent in this yet with some of the storms starting up?

[radarman]

  On 11/17/2015 at 11:41 PM, salbers said:

Has there been a dent in this yet with some of the storms starting up?

 

Building a large and robust snowpack will be key.  Slow melt off in the Spring is the best way to recharge stocks.  Good start, but we are still in the 1st quarter... Need several hundred more inches in the mountains before any kind of dent can be talked about IMO.

[salbers]

True it's early, though this map shows well above normal Sierra snowpack at this point.

 

http://ski.curbed.com/archives/2015/11/el-nino-snow-california-.php

[thewxmann]

  On 11/17/2015 at 11:41 PM, salbers said:

Has there been a dent in this yet with some of the storms starting up?

 

Last year started out very similarly with lots of storms in Nov/Dec. Then Jan onwards it dried up. (Jan ended up with no rain accumulations in many locations.)

[chuck in cali]

would like to see more liquid in general, whatever form, to help with aquifers and reservoirs 

[Utrex]

  On 11/18/2015 at 12:41 AM, thewxmann said:

Last year started out very similarly with lots of storms in Nov/Dec. Then Jan onwards it dried up. (Jan ended up with no rain accumulations in many locations.)

There is no comparison snowpack-wise.

[OKwx2K4]

Good for California.

[thewxmann]

  On 12/14/2015 at 9:42 PM, Utrex said:

There is no comparison snowpack-wise.

 

True, last year's early winter storms were all warm in nature. The storms this year have been much colder with temperatures dipping to freezing after the storm passes. All in all, a good sign.

[A-L-E-K]

nino is starting to deliver

[Utrex]

Very positive results are coming from the snowpack:

The Northern Sierra is essentially at normal (98%), compared to April 1st of this year (28%).

Central Sierra is doing very well too. Southern Sierra still needs time though. However, it is far better than the snowpack from April 1 (19%).

[Utrex]

Snowpack now above-average!

[jm1220]

And more coming too, for low elevations with the next system. Great news for the reservoirs in the state, which will have a good intake of water from the mountains during the dry season. Hopefully the pattern shifts to southern CA storms later in the winter, as they haven't seen as much rain as elsewhere.

[salbers]

Looks like SoCal has a couple of storms coming up on the GFS - on schedule with a January pattern shift.

[chuck in cali]

hey man, 16th century is a long time ago. did they have measure cups and such back in that day

[Chinook]

This should be the first couple of rainstorms to really focus in on California

 

[Quincy]

Quite a bit of urban and poor-drainage flash flooding today around Los Angeles. Not seeing too many complaints about the rain though. 

[Chinook]

The last 7 days (mostly last 2 days) of precipitation in California looks healthy

 

[ice1972]

The drought will soon be over......such is life on the best coast......

[thewxmann]

  On 1/19/2016 at 7:03 AM, ice1972 said:

The drought will soon be over......such is life on the best coast......

 

Not even close.

 

Can't speak for SoCal but here in the Bay Area, the amount of rain we have received so far this rainy season has been about average. Snowpack in the Sierra is also around average (110% of normal). This speaks to how dry the past few years have been.

 

To bust the drought, we need a record-wet rainy season, with records going back to the 1800's.

[Chinook]

This has been a positive couple of weeks in California, with some areas of 200% of normal precipitation within the last couple of weeks

 

[Quincy]

We probably won't see any major drought reduction in tomorrow's Drought Monitor update, but the recent pattern is a start. Rainfall amounts this month are already 3-4+ times as much as the region saw all of last January.